Milk quality research project. Organoleptic study of milk Results of the study of milk and dairy products

Milk sampling rules.

After opening the flasks or tanks, use a spatula to scrape off the fat accumulated on the lids and walls into the same containers and mix thoroughly with a whorl, moving it up and down 8-10 times. Milk samples are taken from flasks with metal cylindrical tubes with holes at the ends with a diameter of 9 mm or circles with elongated handles with a capacity of 0.25 or 0.5 liters. About 500 ml of milk should be taken for analysis. Samples taken are usually subjected to immediate testing. In exceptional cases, as a preservative, you can use a 40% solution of formalin (1 - 2 drops per 100 ml of milk) or a 10% solution of potassium dichromate at the rate of 1 ml per 100 ml of milk. Data on the quantity and name of the preservative are indicated in the accompanying document.

Milk that goes on sale in packaged form is selected for analysis in its original packaging (in bottles or bags) (GOST R52054-2003). Determination of the purity of milk. To determine the purity of milk, devices of the Record type are used with cotton or flannel filters with a diameter of 27 ... 30 mm. Well-mixed, warmed up to 35 ... 40 ° C, the test milk (250 ml) is poured into the vessel of the device. After filtration is completed, the filter is dried in air, placing it on a sheet of parchment paper, at the same time protecting it from dust contamination, and then, comparing the nature of the sediment on the filter with the attached standards, a conclusion is made about the degree of milk purity.

Table 1

Organoleptic characteristics of pasteurized cow's milk

Density determination milk

A thoroughly mixed milk sample (500 ml) is carefully poured along the wall into the cylinder, where the lactodensimeter is slowly immersed, after which it is left in a free floating state, making sure that it does not touch the walls of the cylinder. After the lactodensimeter is set in a stationary state, the milk density and temperature are read. The reading must be carried out in such a way that the eye level coincides with the upper edge of the meniscus along which the reading is taken. Density is determined at a temperature of 20°C. In the event that the temperature of the milk is above or below 20 ° C, corrections are made. The density of the prepared milk must be at least 1.027 g/cm.

Determination of fat content in milk

10 ml of concentrated sulfuric acid (density 1.81 ... 1.82 g / cm 3) is poured into the butyrometer (butyrometer), then 10.77 ml of milk and 1 ml of isoamyl alcohol are carefully layered along the butyrometer wall, after which they are closed with a cork.

To dissolve milk proteins, a tightly closed butyrometer is turned over 4-5 times, then placed in a water bath at a temperature of 65 ° C with a stopper down for 5 minutes, after which it is centrifuged at a speed of at least 1000 rpm for 5 minutes, then placed again in a water bath. bath at a temperature of 65 ° C, and then quickly count the fat. When counting, the butyrometer is held vertically, the border of fat should be at eye level, the price of one whole division corresponds to 0.1% of fat.

Determination of milk acidity

The acidity of milk is expressed in Turner degrees (the amount of 0.1N sodium hydroxide solution (ml) used to neutralize 100 ml of milk).

Research progress:

In a conical flask with a capacity of 250 ml add 10 ml of milk;

Add 20 ml of distilled water;

2 - 3 drops of an alcohol solution of phenolphthalein;

The mixture is stirred;

Titrate with 0.1N. with a solution of caustic soda until a persistent, not disappearing within 1 min, faint pink color appears.

The amount of caustic soda used for titration of the studied milk and multiplied by 10 corresponds to its acidity.

Quite fresh milk has an acidity of 16-18, fairly fresh 20-22, stale -23 or more. Milk diluted with water or with an admixture of soda has an acidity of 16. Turner (Turner degree - the amount of 0.1 N sodium hydroxide solution per ml used to neutralize 100 ml of milk).

Determination of bacterial contamination of unpasteurized milk

An indirect indicator of bacterial contamination of unpasteurized milk is a test with resazurin. (Pour 1 ml of a 0.014% solution of resazurin and 10 ml of the test milk into two sterile test tubes, close with sterile stoppers, and then mix, carefully turning over (do not shake!) the test tubes three times, after which they are placed in a water bath at a temperature of 38. ..40 C. The water level in the water bath should be slightly higher than the liquid level in the test tubes.20 minutes after placing the test tubes in the water bath, carefully, avoiding shaking, take them out and evaluate the color. In the presence of paint, the tubes are carefully turned over and left in a water bath for another 40 minutes, after which, according to the characteristics of the developed color, the degree of bacterial contamination of milk is judged (see the table below)

table 2

Assessment of bacterial contamination of milk
Quality class	Milk quality	Color development time	Milk coloring	The number of bacteria in 1 ml of milk
	Good	After 1 hour	Grey-lilac to lilac with a slight gray tint	Less than 500 thousand
	Satisfactory	After 1 hour	Lilac with a pink tint or hot pink	From 500 thousand to 4 million
	bad	After 1 hour	Pale pink or white	4 to 20 million
	Very bad	In 20 minutes	White	More than 20 million

From the standpoint of microbiological safety in milk and dairy products, the following indicators are normalized: total microbial count; coli-forms (BGKP); pathogenic microorganisms - salmonella, listeria, staphylococcus, yeast (except for drinks containing yeast starters) and molds.

Definition of Outsiders impurities

Soda can be added to milk (in order to falsify freshness) and starch (to preserve the consistency and color of whole milk if it is diluted with water or cream is removed).

Determination of starch impurities

10 ml of the test milk is added to the test tube, then it is boiled to convert the starch into a paste, and after cooling, a few drops of Lugol's solution are added and mixed. In the presence of starch, a blue color develops. Impurities of starch to milk are not allowed.

Determination of soda in milk

The method is based on the appearance of a green color of a bromthymol blue solution in the presence of sodium carbonate or bicarbonate. 5 ml of milk is added to the test tube, and then, avoiding shaking, 7-8 drops of a 0.04% alcohol solution of bromthymol blue are carefully layered along the wall. A green color that appears after 10 minutes indicates the presence of soda in milk. In the absence of soda, the annular layer has a yellow color.

Impurities of soda to milk are not allowed.

Chemical research

From the standpoint of chemical safety, toxic elements are controlled in milk and products of its processing (lead, arsenic, cadmium, mercury; and in butter, after storage, copper and iron are also controlled); mycotoxins (aflatoxin M, and in oil - aflatoxin B 1); radionuclides (cesium-137, strontium-90); antibiotics (levomycetin, tetracycline group, streptomycin, penicillin); inhibitory substances; pesticides (hexachlorocyclohexane, DDT and its metabolites, as well as pesticides that were used in the production of raw materials).

The main physical and chemical indicators of various types of milk, defects and possible causes of changes in its freshness are presented in tables 3 and 4.

Table 3

Type of milk	Norm indicators
	Mass fraction of fat, % not less than	Density, g/cm3, not less	Acidity, no more	Degree of purity according to the standard	Soder. vitamin C, mg,%, not less than	Temp., С, not higher	The presence of phosphatase	Degrease. dry residue c, g
pasteurized,
pasteurized,
pasteurized,
ghee,
ghee,
Protein,
Vitaminized
Whole
Low fat

Table 4

The main defects of fresh milk and their possible causes

Milk vices	Likely Causes
Consistency
mucosal	Mucus-forming lactic and putrefactive microorganisms, colostrum impurities, mastitis in animals.
frothy	Bacteria from the group of Escherichia coli, yeast, butyric fermentation.
watery	Dilution with water, thawing of incorrectly frozen milk.
Color
bluish	Pigment-forming microorganisms, dilution with water, skimming, storage in galvanized utensils, feed pigments.
· yellow	Pigment-forming microorganisms, colostrum impurities, feed pigments, medicines.
Smell
ammonium	Bacteria of the Escherichia coli group, long-term storage in an open container.
smoky	Violation of the technology of pasteurization and preparation of dishes (“frying”).
fish	Hydrolysis of lecithin with the formation of trimethylamine, adsorption of odor during joint storage with fish.
putrid	putrefactive microorganisms.
musty	Microbiological processes during storage in closed vessels.
Taste
fish	Hydrolysis of lecithin with the formation of trimethylamine.
· bitter	Putrefactive bacteria, potato and hay bacillus, yeast, admixture of colostrum, medicinal substances, use of wormwood, field mustard in animal feeding.
soapy	The addition of soda, the presence of horsetail in the feed of animals, udder tuberculosis.
rancid	Rancidity of fats under the influence of lipolytic enzymes of microorganisms, bacteria of butyric fermentation, exposure to direct sunlight, high air temperature.
Feed flavors	Does not require clarification.
metallic	Storage in poorly tinned dishes.
brackish	Colostrum impurities, mastitis, udder tuberculosis, dilution with highly mineralized water.

Protocol

(studies of the good quality of milk)

Milk (grade, type)

Organoleptic indicators: color_______ smell_________

Consistency______________

Physical and chemical research:

1. Identification of naturalness

density of milk __________

2. Freshness rating

acidity in Turner degrees

(give calculations) ____________

boiling test _________

alcohol test __________

3. Determination of foreign matter

reaction to the presence of soda ____________

reaction to the presence of starch



Khachatryan A.Yu. 1

Smirnova D.V. 1

1 OGBPOU "Kostroma Regional Medical College named after S. A. Bogomolov"

The text of the work is placed without images and formulas.
The full version of the work is available in the "Job Files" tab in PDF format

Introduction

The life of any person is unthinkable without milk. Our survey (150 people, questionnaire Appendix 1) showed that they often buy it as a component of a healthy diet, but most people do not know why milk is really useful.

Milk is considered to be a universal food product. It is difficult to enumerate the number and categories of food products in the preparation of which this valuable and wonderful product is used. The importance of milk in children's and dietary nutrition is undeniable. In addition to the main components - proteins, carbohydrates and fats, milk contains about 200 useful substances. In terms of nutritional value, that is, meeting the physiological needs of the body in basic microelements, milk is a unique product and can replace any product, but not a single product can replace milk.

Of course, in order for milk to become an assistant in maintaining health, timeliness and regularity of intake are necessary, however, as well as the quality of the consumed product. It is very important to eat high-quality milk, in which the chemical composition and nutritional value are as balanced as possible.

Currently on the shelves of Kostroma stores there is a large selection of milk from various producers in our region and other regions of our country. Interest in the quality of milk and dairy products among the population is always constant.

Hypothesis: if you analyze milk and find out which manufacturer produces the highest quality and healthiest product, then you can recommend this brand for regular consumption.

Goal of the work: study of the quality of milk of various brands sold at retailers in Kostroma.

Tasks:

conduct a survey of consumer preferences for milk of students and teachers.

to study the literature in order to establish the factors that determine the quality and value of a given product;

to master the methods for determining the organoleptic and physico-chemical parameters of milk from various manufacturers sold in the retail food chain of the city of Kostroma;

Subject of study: organoleptic and physico-chemical parameters of milk.

Object of study: milk of various brands sold in Kostroma.

Research methods:

Theoretical methods. Experimental: the method of organoleptic evaluation of smell and taste, the method for determining the density of milk by the areometric method, the gravimetric method for determining the dry matter, the indicator method for determining acidity, the acid method for determining fat, the method for determining protein according to Kjeldahl,

Research methodology.

Method for determining organoleptic indicators.

Organoleptic indicators must comply with the following parameters:

Name of indicator	Name of indicator
Appearance	Opaque liquid. For products with a fat mass fraction of more than 4.7%, a slight settling of fat is allowed, which disappears when mixed.
Consistency	Liquid, homogeneous non-viscous, slightly viscous. Free of protein flakes and tangled fat clumps
Taste and smell	Characteristic for milk, without foreign tastes and odors, with a slight aftertaste of boiling. For baked and sterilized milk - a pronounced taste of boiling. Sweet taste allowed
	White, allowed with a bluish tint for skimmed milk, with a light cream tint for sterilized milk, with a creamy tint for baked milk

Method for determining physico-chemical parameters.

Method for determining the density of milk.

To determine the density of milk, we used the hydrometric method based on determining the volume of the displaced liquid and the mass of the hydrometer floating in it.

Determination of the density of raw, drinking, skimmed cow's milk is carried out at a temperature of (20 ± 5) °C. 250 or 500 cm3 samples for analysis are thoroughly mixed and carefully, in order to avoid the formation of foam, pour along the wall into a dry cylinder, which should be held in a slightly inclined position.

The cylinder with the analyzed sample is installed on a flat horizontal surface and the temperature of the sample (t 1) is measured. The reading of temperature readings is carried out no earlier than 2-4 minutes after lowering the thermometer into the sample.

A dry and clean hydrometer is slowly lowered into the analyzed sample, immersing it until 3-4 mm remains to the expected mark of the hydrometer scale. Then leave it in a free floating state. In this case, the hydrometer should not touch the walls of the cylinder.

The first reading of the density readings (p 1 ,) is carried out on the hydrometer scale 3 minutes after it is established in a stationary position. After that, the hydrometer is carefully raised to the height of the ballast level in it and lowered again, leaving it in a free floating state. After establishing it in a stationary state, a second reading of the density readings (p 2) is carried out. The operator's eyes should be at the level of the meniscus when reading the density reading. The readings are taken along the upper edge of the meniscus.

Reading of indications on hydrometers of type AON-1 or AON-2 reading of indications is carried out to the price of the smallest division. Then repeat the measurement of the sample temperature (t 2).

The arithmetic mean of the results of two temperature measurements t 1 and t 2 rounded to the first decimal place is taken as the result of measuring the temperature of the analyzed sample of the product (G).

For the result of measurements of the density of the analyzed sample of the product (p cf) at the temperature t of the analyzed sample, the arithmetic mean of the results of two hydrometer readings p 1 and p 2, rounded to the first decimal place, is taken.

Dry matter determination method

A glass bottle with 20-30 g of well-washed and calcined sand and a glass rod that does not protrude beyond the edges of the bottle is placed in an oven (Appendix 2, Fig. 3) and kept at 102 ± 2 "C for 30-40 minutes. After that the vial is removed from the oven, covered with a lid, cooled in a desiccator for 40 minutes and weighed with an error of not more than 0.001 g. 10 ml of milk is added to the same vial with a pipette, closed with a lid and immediately weighed. Then the opened bottle and the lid are placed in an oven with a temperature of (102 ± 2) C. After 2 hours, the bottle is removed from the oven, covered with a lid, cooled in a desiccator for 40 minutes and weighed.

Subsequent weighings are carried out after drying for 1 hour until the difference between two successive weighings is equal to or less than 0.001 g. If an increase in weight is found during one of the weighings after drying, the results of the previous weighing are taken for calculations.

The mass fraction of dry matter C,%, is calculated by the formula:

where m 0 is the mass of the bottle with sand and a glass rod, p

m is the weight of the weighing bottle with sand, glass rod and a sample of the test product before drying. G;

m 1 is the mass of the weighing bottle with sand, a glass rod and a sample of the test product after drying, g.

Method for determining acidity.

We used an indicator method to determine the acidity. The method is based on the neutralization of free acids, acid salts and free acid groups contained in the product with sodium hydroxide solution in the presence of the phenolphthalein indicator.

Place (1.000 ± 0.005) g of phenolphthalein into a 100 ml volumetric flask, add 73 ml of ethanol, stopper and mix gently. The volume of the solution was brought up to the mark with distilled water.

Milk is measured into a conical flask with a capacity of 100 or 250 ml, distilled water is added in volumes of 10 ml of milk and 20 ml of water and 1 ml of cobalt sulfate solution. The mixture is thoroughly mixed.

The mixture is thoroughly mixed and titrated with a solution of sodium hydroxide until a slightly pink color of the milk solution appears, corresponding to the control color standard, which does not disappear within 1 min.

The acidity of the analyzed product, T (in Turner degrees), is calculated by multiplying the volume of sodium hydroxide solution, in cubic centimeters, used to neutralize the acids contained in a certain volume of the analyzed product, by 10. The final result of the analysis is taken as the arithmetic mean of the results of two parallel determinations, rounded to the first decimal place.

Fat determination method.

We determined fat by the acid method. The method is based on the separation of fat from milk under the action of concentrated sulfuric acid and isoamyl alcohol, followed by centrifugation and measurement of the volume of fat released in the graduated part of the butyrometer.

Trying not to wet the throat, pour 10 ml of sulfuric acid into two milk butyrometers with a dispenser and, carefully so that the liquids do not mix, add 10.77 ml of milk with a pipette, placing the tailbone of the pipette to the throat at an angle. The level of milk in the pipette is set at the lowest point of the meniscus. The milk should flow out of the pipette slowly. After emptying, the pipette is removed from the neck of the butyrometer not earlier than after 3 s. Blowing milk out of a pipette is not allowed. Add 1 ml of isoamyl alcohol to the butyrometers with a dispenser.

The level of the mixture in the butyrometer is set 1-2 mm below the base of the butyrometer neck, for which it is allowed to add a few drops of distilled water.

Butyrometers are closed with dry plugs, introducing them a little more than halfway into the neck of the butyrometers. Butyrometers are shaken until the protein substances are completely dissolved, so that the liquids in them are completely mixed.

Install the butyrometers with the stopper down for 5 minutes in a water bath at a temperature. (65 ± 2) degrees. After removing from the bath, the butyrometers are inserted into the centrifuge glasses with the graduated part towards the center. Butyrometers are arranged symmetrically, one against the other. With an odd number of butyrometers, a butyrometer filled with water instead of milk, sulfuric acid and isoamyl alcohol in the same ratio as for analysis is placed in the centrifuge.

Butyrometers are centrifuged for 5 minutes (Appendix 2, Fig. 1). Each butyrometer is removed from the centrifuge and the column of fat is adjusted by moving the rubber stopper so that it is on the graduated part of the butyrometer.

Butyrometers are immersed with stoppers down for 5 minutes in a water bath at a temperature of (65 ± 2) "C. In this case, the water level in the bath should be slightly higher than the level of fat in the butyrometer.

Butyrometers are taken out one at a time from the water bath and a quick reading of fat is carried out. When counting, the butyrometer is held vertically, the border of fat should be at eye level (Appendix 2, Fig. 4 and 5). By moving the cork, the lower limit of the fat column is set to the zero or whole division of the butyrometer scale. The number of divisions is counted from it to the lower point of the meniscus of the fat column with an accuracy to the smallest division of the butyrometer scale.

The interface between fat and acid should be sharp, and the column of fat should be transparent. In the presence of a “ring” (cork) of a brownish or dark yellow color and. various impurities in the column of fat or a blurred lower limit, the measurement is repeated.

After the first centrifugation, in order to facilitate the adjustment of the fat level in the butyrometer, the small stopper is slightly opened without removing it completely. Using a large stopper, set the upper level of the liquid from the graduated part of the butyrometer. Then the smaller hole is tightly hidden. Usually, no noticeable separation of fat is observed after the first centrifugation.

After the second centrifugation and water bath, the position of the liquid level is checked.

The result of intentions is taken as the arithmetic mean of the results of two parallel observations.

Method for determining the mass fraction of protein according to Kjeldahl.

The Kjeldahl method is based on the mineralization of a milk sample with concentrated sulfuric acid in the presence of an oxidizing agent, an inert salt of potassium sulfate and a catalyst - copper sulfate. In this case, the amino groups of the protein are converted into ammonium sulfate dissolved in sulfuric acid.

The mass fraction of nitrogen in this solution is measured chemically by alkalizing the solution, distilling ammonia with steam, absorbing it with a solution of boric acid and titrating the latter with a solution of hydrochloric acid, indicating the equivalence point by changing the color of the indicator.

Measure 1 ml of product into a weighing beaker. 10 ml of sulfuric acid and 10 ml of hydrogen peroxide are added to the Kjeldahl flask (Appendix 2, Fig. 7) or test tube. The Kjeldahl flask or test tube is placed in the aluminum block socket on the electric stove. Set the heating regulator of the tile to the front position.

After the rapid boiling of the contents of the flask or test tube has ceased, approximately 10 minutes after the start of heating, set the heating regulator of the tile to the position corresponding to the maximum. Heating is continued until the liquid becomes clear, colorless or slightly bluish. The Kjeldahl flask with the obtained mineralizate is cooled in air to room temperature.

Add 20 ml of distilled water to the Kjeldahl flask with mineralizate and mix thoroughly in a circular motion until the precipitate dissolves. Assemble the distillation apparatus (see appendix fig. 2). Turn on the electric stove under the steam generator flask, open the clamp on the steam outlet line and the sewer, and close the clamp on the steam supply line to the Kjeldahl flask. Heat the flask and the converting flask to a boil. The Kjeldahl flask or test tube is attached to the distillation apparatus.

In a conical flask with a capacity of 250 ml, 20 ml of a mixture of boric acid with an indicator solution is measured with a graduated cylinder. Position the conical flask so that the end of the condenser tube is below the top level of the mixture in the flask.

Measure with a graduated cylinder 50 ml of sodium hydroxide solution and carefully, avoiding emissions, pour it through a separating funnel into a Kjeldahl flask. The faucet of the funnel is immediately closed. Close the clamp on the steam outlet line and open the clamp on the steam supply line from the steam generator flask and the Kjeldahl flask or test tube.

The distillation is carried out until the volume of the condensate reaches 90-120 ml (distillation time 5 min). The contents of the conical flask with a solution of the indicator, boric acid and condensate are titrated with a solution of hydrochloric acid with a concentration of 0.2 mol / dm 3 until the color changes to green (Appendix 2, Fig. 6)

The volume of acid used to titrate the contents of the flask is counted.

The mass fraction of total nitrogen X in% with the chemical method of measurement is calculated by the formula:

Where V 1 is the volume of acid used for titration, cm 3;

V 2 - the volume of acids spent on titration during the control measurement,

c - concentration of hydrochloric acid

m is the mass of the sample of the product, g:

1.4 is the conversion factor for the volume a of the acid to the mass fraction of total nitrogen.

The mass fraction of protein Y, % is determined by the formula

Y \u003d 6.38 X where 6.38 is the mass of milk protein, equivalent to a unit mass of total nitrogen.

Main part.

Research results.

Organoleptic indicators.

	Name of product	Research results
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.
		Color: white, externally opaque liquid. Consistency: liquid, homogeneous, not viscous. Taste and smell: typical for milk, without foreign smells and tastes.

Physical and chemical indicators. Indicators of the mass fraction of protein in milk

	Name of product	Normalized value (in %, not less)	Research results (in %, not less)
	UHT milk "House in the village", m.d.zh. 3.2%
	Milk Vologda pasteurized, m.d.zh. 2.5%
	Milk "Prostokvashino" pasteurized, m.d.zh. 2.5%
	Milk "Levashovo" pasteurized, m.d.zh. 3.2%
	Milk "Karavaevo" pasteurized, m.b.zh 2.5%
	Milk "Kosmol" pasteurized m.d.zh 1.5%
	Milk "Minsk" pasteurized m.d.zh 2.5%
	Milk "MolProm" pasteurized, m.d.zh 2.5%

Indicators of the mass fraction of fat in milk

	Name of product	Normalized value (in %, not less)	Research results (in %, not less)
	UHT milk "House in the village", m.d.zh. 3.2%
	Milk Vologda pasteurized, m.d.zh. 2.5%
	Milk "Prostokvashino" pasteurized, m.d.zh. 2.5%
	Milk "Levashovo" pasteurized, m.d.zh. 3.2%
	Milk "Karavaevo" pasteurized, m.b.zh 2.5%
	Milk "Kosmol" pasteurized m.d.zh 1.5%
	Milk "Minsk" pasteurized m.d.zh 2.5%
	Milk "MolProm" pasteurized, m.d.zh 2.5%

Density indicators

	Name of product	Normalized value (kg / m 3, not less)	Research results (kg / m 3, not less)
	UHT milk "House in the village", m.d.zh. 3.2%
	Milk Vologda pasteurized, m.d.zh. 2.5%
	Milk "Prostokvashino" pasteurized, m.d.zh. 2.5%
	Milk "Levashovo" pasteurized, m.d.zh. 3.2%
	Milk "Karavaevo" pasteurized, m.b.zh 2.5%
	Milk "Kosmol" pasteurized m.d.zh 1.5%
	Milk "Minsk" pasteurized m.d.zh 2.5%
	Milk "MolProm" pasteurized, m.d.zh 2.5%

Acidity indicators

	Name of product	Normalized value (degrees Turner, no more)	Research results (degrees Turner, no more)
	UHT milk "House in the village", m.d.zh. 3.2%
	Milk Vologda pasteurized, m.d.zh. 2.5%
	Milk "Prostokvashino" pasteurized, m.d.zh. 2.5%
	Milk "Levashovo" pasteurized, m.d.zh. 3.2%
	Milk "Karavaevo" pasteurized, m.b.zh 2.5%
	Milk "Kosmol" pasteurized m.d.zh 1.5%
	Milk "Minsk" pasteurized m.d.zh 2.5%
	Milk "MolProm" pasteurized, m.d.zh 2.5%

Dry matter content

	Name of product	Normalized value (in %, not less)	Research results (in %, not less)
	UHT milk "House in the village", m.d.zh. 3.2%
	Milk Vologda pasteurized, m.d.zh. 2.5%
	Milk "Prostokvashino" pasteurized, m.d.zh. 2.5%
	Milk "Levashovo" pasteurized, m.d.zh. 3.2%
	Milk "Karavaevo" pasteurized, m.b.zh 2.5%
	Milk "Kosmol" pasteurized m.d.zh 1.5%
	Milk "Minsk" pasteurized m.d.zh 2.5%
	Milk "MolProm" pasteurized, m.d.zh 2.5%

Conclusion

As a result of the survey, the majority of respondents buy milk in a supermarket or store for themselves and family members in a carton. They prefer milk of trade marks Karavaevo and Vologda with pasteurized fat content of 2.5%. It turned out that the respondents did not understand the difference in the degree of processing of milk and could not explain why it is useful. In their choice, they are guided primarily by the date of manufacture and shelf life, least of all they pay attention to the price, fat content and manufacturer.

As a result of the analysis of the organoleptic and physico-chemical properties of milk of 8 brands sold in the retail network of the city of Kostroma, we did not find deviations from GOST.

Bibliography

1. GOST 31450-2013 Drinking milk. Specifications.

2. Skurikhin N. M., Nechaev A. P. Everything about food from the point of view of a chemist. - M.: Higher school, l99l.

3. Workshop on the basics of agriculture. — M.: Enlightenment, 1991

4. GOST 23327-98. Milk and dairy products. Method for measuring the mass fraction of total nitrogen according to Kjeldahl and determining the mass fraction of protein.

5. GOST R 54758-2011. Milk and milk processing products. Density determination methods.

6. Zhvanko Yu. N., Pankratova GV, Mamedova 3. I. Analytical chemistry and technological control in public catering. - M .: Higher School, 1989.

7. GOST 28283-89 Cow's milk. Method of organoleptic evaluation of smell and taste

8. Zlotnikov E. G., Estrin Z. R. Features of the organization of experimental work // Chemistry at school. - 1997. - No. 4. - S. 66-68.

9. GOST 23327-98. Milk and dairy products. Method for measuring the mass fraction of total nitrogen according to Kjeldahl and determining the mass fraction of protein.

10. GOST 5867-90 Milk and dairy products. Methods for determining fat

11. GOST R 54758-2011. Milk and milk processing products. Density determination methods.

12. GOST R 54669-2011. Milk and milk processing products. Methods for determining acidity.

13. GOST 3626-73. Milk and dairy products. Methods for determining moisture and dry matter.

Annex 1

Questionnaire for the survey of milk consumers

Your gender: M F Age:

1. What kind of milk do you buy more often:

A) natural; b) with a fat norm of 2.5%; c) with a fat norm of 3.2%;

d) with a fat norm of 1.5%; e) Melted; e) does not matter;

2. How often do you buy milk:

a) every day b) once a week c) twice a week; d) once a month

3. How much do you usually buy when going to the store:

a) less than a liter; b) liter; c) 1.5-2 liters; d) more than 2 liters.

4. Specify the place of purchase:

a) a supermarket b) Shop; c) Stall (outside the market); d) the market;

e) a specialized dairy shop;

5. Which brand of milk do you prefer:

aSavushkin product; Prostokvashino; Karavaevo, Levashovo, Minsk, Vologda, House in the village, Zdravushka; Lianozovskoe; Brest Litovsk, Borovikovo, Other___________________

6. What do you pay attention to when choosing milk:

Price; Manufacturer; Taste qualities; brand popularity; Quality; % fat; storage period; date of manufacture; presence of quality marks; type of processing; package

7. Preferred form of packaging:

a) Cardboard; b) Plastic bottle; c) glass bottle; d) plastic bag; e) in bottling

8. Do you always pay attention to the expiration date: and sometimes; b) always; c) never; d) if there is time.

9. Why do you buy milk: a) Component of a healthy diet; b) Daily diet; c) for cooking; d) delicious; Other________________

10. At what price do you buy milk (for 1 liter) _______________(write in rubles)

11. Do you know why milk is good for: Specifically why I do not know; No; Yes, because _________________________________________________________

12. Who do you buy milk for: for myself; for adult family members; for children; for friends and acquaintances; for animals.

13. What type of milk processing do you prefer: pasteurized; sterilized; ultra pasteurized; fresh (on tap); melted; Hard to say.

Annex 2

Rice. 1. Centrifuge

Rice. 2. Device for distillation of ammonia. Rice. 3. Drying cabinet

Rice. 4 and 5. Determination of fat content. Butyrometers (Butyrometers)

Rice. 6. Determination of protein. Titration. Rice. 7. Kjeldahl flask

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Introduction

1.3 Requirements for the quality of drinking milk

1.4 Processes occurring in drinking milk during storage

1.5 Factors that shape the quality of drinking milk

2. Study of the quality of drinking milk

2.2 Objects of study

2.3 Research methods

2.3.1 Determination of organoleptic indicators of the quality of drinking milk

2.3.2 Determination of physical and chemical indicators of the quality of drinking milk

2.4 Results of drinking milk study

2.4.1 Evaluation of organoleptic indicators of the quality of drinking milk

2.4.2 Assessment of physicochemical and microbiological indicators of the quality of drinking milk

Conclusion

List of used literature

Introduction

The work consists of the following sections: introduction, theoretical foundations for the formation of the assortment and quality of drinking milk, research on the quality of drinking milk from well-known manufacturers. This course work presents studies of the quality of drinking pasteurized milk from different manufacturers in terms of organoleptic, physico-chemical quality indicators and microbiological safety indicators, the results of determining the quality level of samples, and complex indicators of drinking pasteurized milk are calculated. Based on the results of the research, conclusions and suggestions are given.

“Among the varieties of human food, milk is in an exceptional position as food prepared by nature itself” (Academician I.P. Pavlov). Milk and products based on it accompany a person from the first days of life. In ancient medical treatises and canons, doctors called milk "white blood", "juice of life" and believed that it could cure a person from a thousand diseases. Experts estimate that people have been drinking milk for over 8,000 years. With the transition to a market economy, there was a significant expansion of trade relations, which, in turn, led to the saturation of the Russian market with a variety of products, both domestic and imported. First of all, this applies to milk and dairy products. Therefore, the problem of a multilateral study of the product, as well as a clearer approach to indicators characterizing its quality, is relevant. The problem of choice remains important for the modern consumer. The abundance of dairy products forces the consumer to decide: what suits him; which manufacturer to prefer; how much effort and financial resources will be spent in search of the most optimal option.

But not every consumer is able to make the right choice among the wide range on the market. Therefore, today the problem of consumer choice is becoming more and more relevant for us.

The objects of study were 5 samples of pasteurized drinking milk produced in accordance with GOST R 52090-2003: sample 1 Prostokvashino of Wimm-Bill-Dann OJSC; sample 2 - "Kuban Burenka" UNIMILK; sample 3 - "In the meadow" UNIMILK, sample 4 - "Merry milkman" JSC "Wimm-Bill-Dann", sample 5 - "Kuban milkman" CJSC "Cheese-making plant Leningradsky".

The purpose of the course work is to conduct a comprehensive assessment of the quality of drinking milk, the requirements of milk standards, the procedure and methods for the examination of milk. Based on the goal, the following tasks can be set:

Consider basic information about milk, its chemical composition;

To reveal the range and requirements for the quality of drinking milk;

To characterize the consumer properties of drinking milk;

Consider the factors that shape the quality of the quality of drinking milk;

To reveal the factors influencing the safety of the quality of drinking milk;

Consider the features of the study of the quality of drinking milk.

1. Theoretical foundations for the formation of the assortment and quality of drinking milk

1.1 Chemical composition and nutritional value of drinking milk

The chemical composition of cow's milk is extremely diverse. Milk contains everything necessary for the life and normal development of a living organism - more than 100 different substances: proteins, fats, 19 amino acids and a few more fatty acids, a set of sugars, more than 25 minerals, a complex of the most valuable vitamins, various pigments, hormones, enzymes and , finally, in fresh milk - immune substances. Moreover, many of these substances are found only in milk. So, strictly specific to it: from carbohydrates - milk sugar, lactose; from proteins - milk protein, casein, as well as milk fat with its unique set of fatty acids.

The remarkable properties of milk include a successful balance of the main components - proteins, fats and carbohydrates; the ability to excite the digestive glands and cause the secretion of digestive juices even in the absence of appetite; high digestibility with minimal consumption of gastric juice. Some beneficial properties of milk are even more enhanced in fermented milk products.

Due to the listed properties, milk is successfully used to feed children and the elderly, and is also the main dish in the diet of patients. The daily intake of milk for an adult is 0.5 liters, for a child - about 1 liter.

Milk consists of water - about 88% and dry residue - 12%. The composition of the dry residue contains milk fat, proteins, milk sugar, salts and other substances. Milk solids form a complex polydisperse system with water, in which some substances, such as milk sugar and salts, are dissolved in water, which serves as a dispersion medium for them. A solution of salts is a dispersion medium for proteins and maintains them in a colloidal state, and a dispersion medium for fat is the entire milk plasma, it can form an emulsion or suspension with it.

The degree of dispersion of individual substances is different. So, milk sugar and salts form molecular and ionic solutions, protein substances - a colloidal solution, milk fat is in the form of coarse particles - fat globules.

Quantitative changes in the content of individual substances of milk during the year are inversely proportional to the degree of their dispersion. Therefore, the most constant amount of milk sugar and milk salts, which are most finely dispersed in milk, and significant fluctuations in fat content. In this regard, the nutritional value of milk is judged by the SOMO indicator - the dry fat-free milk residue, it is determined by subtracting the fat content from the total dry residue.

Milk proteins are the most nutritionally valuable part of milk, they consist of casein and whey proteins - albumin and globulin. In addition to them, milk contains proteins of the shells of fat globules and some other little-studied protein substances, as well as nitrogenous compounds. Milk proteins have an extremely favorable quantitative and qualitative composition of amino acids, including all essential amino acids. Therefore, milk proteins are considered complete.

The main mammalian milk protein - casein - is contained in an amount of about 2.7%, which is about 80% of the total amount of milk protein. It belongs to complex proteins - phosphoproteins. Phosphorus is part of the casein molecule in the form of a phosphoric acid residue (organic phosphorus), it is most easily absorbed; phosphorus is also adsorbed on the surface of molecules in the form of calcium phosphate (inorganic phosphorus). In milk, casein is combined with calcium in the form of soluble calcium caseinates. In milk, casein forms a colloidal solution. Unlike other proteins, casein is not coagulated by rennet. Casein is relatively resistant to high temperatures, but coagulates when boiled for a long time. When milk souring under the influence of an increasing concentration of lactic acid and hydrogen ions, casein gradually loses its electrical charge. Under these conditions, protein coagulation and clot formation are observed. When the pH is below 4.7, the casein molecule acquires a positive charge and the clot begins to dissolve.

Albumin is found in milk in an amount of about 0.4%. It belongs to the group of simple proteins - proteins. Albumin is characterized by a high sulfur content: twice as much as in casein. It is highly soluble in water, as well as in weak acids and alkalis. In milk, it is in the state of the greatest dispersity compared to other proteins, forming particles with a size of 15-20 nm. Albumin is a thermolabile protein. At a temperature of 60°C, the hydration shell surrounding the protein particles weakens and gradually breaks down, which leads to the release of albumin in the form of flakes resulting from protein denaturation. At 85°C and above, albumin completely precipitates and loses its ability to dissolve in water.

Globulin also refers to simple proteins, found in milk in an amount of 0.1%. It dissolves well in dilute salt solutions, in milk, easily denatures and coagulates when its solutions are heated to 80 ° C in a slightly acidic medium.

Nitrogen compounds of a non-protein nature are found in milk in an amount of up to 0.2%. These include free amino acids, peptones, polypeptides, urea, uric acid, creatine and creatinine, etc. They enter milk from breast cells as products of protein metabolism in the body.

Milk fat belongs to the group of simple lipids, is a mixture of triglycerides, the molecule of which is formed by glycerol and three molecules of various fatty acids with an unequal degree of hardness. Of all the known dietary fats, milk fat is the most valuable. It is distinguished by a rare set of fatty acids, a pleasant specific taste and high digestibility. The glyceride composition of milk fat is quite complex: it contains more than 60 fatty acids with a number of carbon atoms from 4 to 20. Saturated fatty acids predominate in the composition of fat: palmitic, myristic, stearic, they make up 58% in summer, and 71 in winter. %. In the unsaturated group, the main one is oleic acid (30-40%).

A feature of the fatty acid composition of milk fat is a relatively high content of saturated low molecular weight (volatile) fatty acids, such as butyric, caproic, caprylic and capric. These acids make up from 7 to 9%, which is much higher than their content in other animal fats, where they occur in the form of traces. Of the complex lipids, milk contains phosphatides (0.02-0.03%), mainly lecithin, and small amounts of cephalin. Lecithin is part of the shells of fat globules. It is a colorless substance that quickly darkens in air, has the property of an active emulsifier.

Milk also contains cholesterol, which can form esters with fatty acids - cholesterol. The usual companion of cholesterol - ergosterol can be converted under the influence of ultraviolet rays into vitamin D. Fat in milk is in the form of an emulsion consisting of round or slightly oval fat globules. Fat globules are surrounded by a protein-lecithin shell, which prevents their fusion and serves as a natural protection against oxidation. 1 ml of milk contains about 4 billion fat globules. A high degree of fat dispersion has a positive value V nutrition: due to the developed surface, fat is easily emulsified, well processed by bile acids and almost completely absorbed (93-96%). The absorption of fat is facilitated by its low melting point.

Milk carbohydrates are represented mainly by milk sugar - lactose, the content of which is on average 4.7%. In addition to lactose, small amounts of monosaccharides are present in milk: glucose and galactose - 13.5 mg% and their derivatives - phosphate sugars and amino sugars.

Lactose belongs to the group of disaccharides, its molecule consists of two molecules of hexoses - glucose and galactose. Under natural conditions, lactose is found only in the milk of mammals, which can serve as the only source of its production. Of all the sugars, lactose is the least sweet, 5-6 times less than sucrose. This is of great biological importance, since, despite the high content of lactose (up to 5%), milk has only a slightly sweet taste, which does not prevent its consumption in large quantities.

Milk sugar is more slowly hydrolyzed by acids and enzymes than other sugars. Therefore, in the digestive tract, it reaches the small intestine, where it can be used to feed the lactic microflora and promote the habitation of these beneficial bacteria in the intestine. Milk sugar serves as the starting material for various types of fermentation - lactic acid, alcohol, propionic acid, used in the whole milk and cheese industry for the production of fermented milk products and cheeses.

Minerals are represented in milk by various salts contained in an amount of about 1%. Milk salts are least subject to quantitative changes depending on the season of the year, territorial feature, livestock breed and other factors; their content in milk is quite constant. The composition of mineral substances includes cations - potassium, sodium, calcium, magnesium, iron and others, as well as anions - PO 4, SO 4, Cl. These substances are present in milk in the form of salts, mainly phosphoric and citric acids, chlorides are found in smaller quantities. A person's need for calcium can only be satisfied with milk, since 1 liter of it contains 1.2 g of calcium, and the daily need for this element is 0.8 g for an adult organism, and 1.2 g for a child.

Milk as a biological fluid contains many enzymes. They are produced in the cells of the mammary gland, are of little importance in milk production technology, as they are destroyed during pasteurization. It is also necessary to take into account the possibility of the formation of enzymes by bacteria that accidentally enter the milk, since they are the cause of various defects in dairy products. Among the most common enzymes are lipase, phosphatase, protease, peroxidase, catalase, reductase. The main amount of proteolytic enzymes in milk is produced by microorganisms. Active proteases are secreted by micrococci and putrefactive bacteria. When they multiply, milk can acquire a bitter taste and curdle with low acidity due to the release of rennet.

Milk contains almost the entire complex of currently known vitamins, but most of them are present in extremely small amounts, completely insufficient to meet the needs of the human body, so milk can be additionally fortified. Milk contains mainly vitamins of the water-soluble group - B 1, B 2, B 6, B 3, C, PP. Fat-soluble vitamins A, D, E are found in dairy products with a high fat content. The quantitative content of constituents in milk is not constant and depends on many factors. The main ones are the conditions for feeding and keeping cows, the breed and health of livestock, and the lactation period.

The chemical composition of milk changes throughout the year, but it differs most sharply in the first days after the calving of the animal. Due to the high protein content of the albumin fraction, colostrum does not withstand pasteurization and is not accepted for processing plants during the first seven days.

1.2 Assortment of drinking milk

All types of milk differ, first of all, in the content of SOMO, in food additives and fillers, as well as in the method of heat treatment. When developing a particular type of milk, first of all, the taste habits of the country's multinational population, the dietary value of the product and the efficiency of its production are taken into account.

In accordance with the technical regulation for milk and dairy products No. 88-FZ, drinking milk is milk with a fat mass fraction of not more than 9 percent, produced from raw milk and (or) dairy products and subjected to heat treatment or other treatment in order to regulate its constituent parts (without the use of whole milk powder, skimmed milk powder).

Depending on the mode of heat treatment, milk is divided into: pasteurized, sterilized, UHT-treated, UHT-sterilized. Pasteurized milk is heat-treated at temperatures up to 100 0 C. Sterilized is milk subjected to homogenization and high-temperature heat treatment at temperatures above 100 0 C. The main difference between sterilized milk and pasteurized milk is high stability at room temperature and characteristic taste features. UHT milk is milk that has been heated to 135°C.

In the production of UHT-treated sterilized milk, the temperature is increased to 140-150 0 С with a holding time of 5 s.

Milk sterilized in this way is closest in properties to pasteurized milk, has a white or slightly yellowish color and taste characteristic of pasteurized milk.

Milk, with the exception of drinking milk from natural milk, depending on the mass fraction of fat, is divided into: skimmed. The actual values ​​of the mass fractions of fat in milk should be no more than the norm of "skimmed" and not less than the norms of "ultra-pasteurized", "sterilized" product.

natural milk It is full fat milk without any additives. It does not enter the sale, as it has a non-standardized content of fat and SOMO and is sent for the production of various types of milk and dairy products. According to Federal Law 88 of 06/12/2008, natural milk - it is a dairy raw material without extracts and additives of dairy and non-dairy components.

Whole milk is milk whose constituents have not been affected by regulation.

normalized milk - milk, the values ​​of the mass fraction of fat or protein, or SOMO of which are brought into line with the standards established in regulatory or technical documents.

Skimmed milk - skimmed part of milk obtained by separation and containing not more than 0.05% fat.

low fat milk - pasteurized milk made from skimmed milk.

High fat milk - normalized milk with a fat content of 4 and 8%, subjected to homogenization.

Baked milk - drinking milk subjected to heat treatment at a temperature of 85 to 99 degrees Celsius with an exposure of at least three hours until specific organoleptic properties are achieved. The main type of drinking milk produced in our country was pasteurized whole milk with a fat content of 3.2% and SOMO 8.1%. In recent years, the production of milk with reduced fat content (2.5, 1% and non-fat) has increased significantly. The production of fortified milk with vitamins C, A and D 2 and high fat content of 4.8% is growing.

fortified milk produce two types: with vitamin C D vitamins C, A and D for preschool children. The content of vitamin C must be at least 10 mg per 100 cm 3 of milk. For the production of fortified milk, it is necessary to have low acidity milk (not more than 18 °T), since the addition of ascorbic acid increases acidity. In order to reduce the loss of vitamins, they are added to milk after pasteurization, but this leads to secondary contamination with microorganisms and a decrease in milk stability.

The new trademarks of pasteurized milk are: milk "For the Whole Family", "Merry Milkman", sterilized, produced under the trademarks "Theme", "Prostokvashino", "Selskoe", "Vkusnoteevo", "White Krynka".

1.3 Factors that shape the quality of drinking milk

Milk processing is carried out immediately after milking. It is filtered and cooled to the lowest possible positive temperatures. Timely cooling of milk helps to prolong its storage.

The milk received at the dairy plant is checked for organoleptic characteristics, acidity and fat content. The received milk is purified from mechanical impurities, then the milk is normalized for fat, i.e., the fat content is reduced or increased, using skim milk (skim) or cream for this.

During the separation and pumping of milk, a partial destabilization of the fat emulsion occurs - the release of free fat on the surface of the fat globules, sticking of the globules and the formation of lumps of fat. To increase the degree of dispersion of the fatty phase, increase its stability, improve the consistency and taste of milk, it is homogenized. To do this, heated milk is sent to homogenizers, where it is passed under high pressure through a narrow slot, as a result of which the fat globules are crushed and their diameter is reduced by 10 times.

Heat treatment of milk is necessary to kill microorganisms and destroy enzymes in order to obtain products that are hygienically safe and have a longer shelf life. For this, pasteurization and sterilization of milk are used.

Pasteurization can be long-term (at a temperature of 63°C, milk can withstand for 30 minutes), short-term (at a temperature of 72°C - for 15-30 seconds) and instant (high-temperature at 85°C and above without exposure). Heat treatment should maximize the nutritional and biological value of milk, not lead to undesirable changes in the physicochemical properties of milk. During the heating process, whey proteins are denatured (structural changes in molecules), and the milk acquires the taste of a boiled product or the taste of pasteurization. As a result of pasteurization and sterilization, the amount of calcium in milk decreases due to the formation of poorly soluble calcium phosphate (precipitates in the form of a milk stone or burn along with denatured proteins). This impairs the ability of milk to rennet coagulation; in the production of cottage cheese and cheese, calcium chloride is added to pasteurized milk.

Sterilization of milk causes the decomposition of lactose with the formation of carbon dioxide and acids - formic, lactic, acetic, etc. Due to the denaturation of the protein of the shells of fat globules, during the sterilization of milk, rendering of fat is observed.

Sterilization of milk in bottles consists in processing it in autoclaves under the following conditions: 104°C - for 45 minutes; 109°C - for 30 minutes; 120°C - for 20 minutes. Sterilization of milk in the flow is carried out at ultrasonic temperatures (UHT) -140-142°C with exposure for 2 s. with subsequent cooling and bottling under aseptic conditions. UHT sterilization promotes greater retention of vitamins in milk than bottle sterilization. Most of all, vitamin C is lost (10-30%). Insufficient heat treatment leads to incomplete inactivation of milk enzymes, which can cause unwanted biochemical processes in milk and dairy products. The result may be a decrease in the quality, taste and nutritional value of products. So, lipases contribute to the rancidity of dairy products, and proteinases of bacterial origin cause UHT milk to coagulate. As a result of pasteurization and sterilization, the physicochemical and technological properties of milk change: viscosity, surface tension, acidity, the ability of milk to settle cream, the ability of casein to coagulate. Milk acquires specific taste, smell and color. The constituents of milk change. Milk is sent to the distribution network at a temperature not exceeding 8°C.

Pasteurized cow's milk intended for direct consumption, is divided into whole (normalized or reconstituted), high-fat, baked, protein, fortified, low-fat, malt. Sterilized - ionic, vitalactate - DM, whole with cocoa or coffee.

Natural is non-skimmed milk that does not contain any impurities. Such milk may vary in fat content and other constituents. It serves as a raw material for the production of other types of milk, as well as dairy products.

Normalized - milk, the fat content of which is brought to a certain norm - 2.5-3.2%. Depending on the fat content of the original milk, it is normalized with skimmed milk or cream according to the calculation, followed by homogenization, pasteurization and cooling.

Reconstituted - milk with a fat content of 2.5-3.2%, produced in whole or in part from powdered spray-dried cow's milk, condensed milk without sugar, whole and low-fat; from skimmed milk, not canned; from cream, butter and melted butter.

High-fat milk is milk brought to a fat content of 6% with cream and subjected to homogenization. Baked milk is milk that is brought with cream to a fat content of 6%, subjected to homogenization and long-term heat treatment at high temperature.

Protein - milk with a high content of dry skimmed substances, produced from milk normalized in terms of fat content, with the addition of dry or condensed whole or skimmed milk.

Fortified - whole or low-fat pasteurized milk with added vitamin C.

1.4 Requirements for the quality of drinking milk

Drinking milk quality is assessed according to GOST R 52090-2003 “Drinking milk. OTU" according to organoleptic and physico-chemical parameters. Among the organoleptic indicators, the appearance, texture, taste and smell, color are established. The most important physical and chemical indicators: mass fraction of fat, density, purity group, acidity, mass fraction of protein.

Milk in appearance is an opaque liquid. For fatty and high-fat products, a slight settling of fat is allowed, which disappears when mixed.

The consistency of milk is liquid, homogeneous, non-viscous, slightly viscous, without protein flakes and lumps of fat. Taste and smell - typical for milk, without extraneous tastes and odors, with a slight aftertaste of boiling. For baked and sterilized milk - a pronounced taste of boiling. For reconstituted and recombined, a sweetish aftertaste is allowed. The color of milk is white, uniform throughout the mass, for baked and sterilized - white with a creamy tint, for skimmed - with a slightly bluish tint.

Mass fraction of product fat:

fat-free - not less than 0.5%

1,2; 1,5; 2,0; 2,5%

2,7; 2,8; 3,0; 3,2; 3,5; 4,0; 4,5%

4,7; 5,0; 5,5; 6,0; 6,5; 7,0%

7,2; 7,5; 8,0; 8,5; 8,9%

Density of drinking milk of various fat content (kg/cm3), not less than: for skimmed milk - 1030, ultra-pasteurized - 1029, sterilized - 1028.

Acidity, T 0 , no more - for fat-free - 21; for ultra-pasteurized, sterilized - 20. Phosphatase in pasteurized, melted and UHT-treated product is not allowed.

The temperature of pasteurized and UHT-treated milk upon release from the enterprise should be in the range from 2 0 С to 6 0 С. , taste, smell and color of milk. In appearance and consistency, milk should be a homogeneous liquid without sediment, baked milk and high fat content - without cream sludge. The smell and taste must be clean, without extraneous flavors and odors not characteristic of fresh milk; for baked milk - a well-pronounced aftertaste of high pasteurization; color - white, with a slightly yellowish tint, for melted - with a creamy, for low-fat - with a slightly bluish tint.

The assessment of the smell and taste of milk is carried out by a commission consisting of at least three experts, specially trained and certified. Smell and taste are determined both immediately after sampling and after their storage and transportation for no more than 4 hours at a temperature of 4 ± 2 °C. The analyzed samples are compared with a pre-selected sample of milk without odor and taste defects, which received a score of 5 points. The results of the evaluation of this sample are not included in the processing.

Immediately after opening the flask determine the smell of milk . Then milk (20 ± 2 cm 3) is poured into a dry, clean glass beaker and the taste is assessed.

1.5 Processes occurring in milk during storage

Milk is subjected to various influences, but primarily mechanical and thermal. Mechanical impact occurs both in the process of obtaining and processing milk, and during transportation. When shaking, stirring, the adsorption layer of fat globules is partially destroyed, as a result of which they can combine into grains, lumps of oil. Disaggregation of casein micelles and foaming also occur.

Heat treatment (heating and cooling) is a mandatory technological operation in the production of dairy products. To enhance the bactericidal properties and, consequently, to preserve the quality of milk immediately after milking, it is necessary to cool it to 2-4 °C. When cooled, the viscosity of milk increases, partial crystallization and stratification of fat globules occur, and pseudoglobulin disintegrates.

Brief freezing of milk is a reversible process. During long-term storage of milk in a frozen state, as a result of freezing pure water, the concentration of electrolytes in the unfrozen part increases, which leads to the discharge of colloidal particles of milk and their precipitation (casein coagulation). After freezing-thawing, wateriness and a sweetish taste of milk are possible as a result of the appearance of water that is not associated with proteins, lactose and other substances.

Heating milk leads to more profound changes than cooling and stirring. When heated, gases and volatile substances are lost. At a temperature of 55 ° C, enzymes begin to break down, at 70 ° C, albumin coagulates, and casein changes only at the border of contact with air. As a result of heating, citric acid decomposes, acidic calcium salts turn into medium ones.

Whey proteins, enzymes and part of vitamins undergo strong changes; the taste of milk changes. Casein and truly soluble constituents of milk change little. Defects in taste and smell depreciate milk the most. Depending on the causes of their occurrence, they are divided into defects of fodder origin, bacterial, technical and physico-chemical. Defects of fodder origin can be the result of the adsorption of odors of feed (silage), barnyard, etc., by milk. Such defects can be weakened or completely eliminated by aeration, deodorization and vacreation of milk. Milk with fodder flavors due to the transfer of alkaloids, essential oils and other substances from the feed is not accepted for processing and is not sold. It is impossible to get rid of such aftertastes by any processing techniques. Some plants affect not only the taste, but also the color and consistency of milk. So, water pepper gives milk an unpleasant taste, a bluish color; herbs ivan-da-marya and maryanik - a bluish color; zhiryanka causes stickiness and ductility. Defects of bacterial origin are reflected in the taste, smell, as well as the consistency and color of milk. They intensify during storage of milk.

Souring of milk is caused by lactic acid bacteria. The reason for this defect is non-compliance with the sanitary and hygienic regime for obtaining, storing and transporting milk. A bitter taste appears in milk as a result of the development of putrefactive bacteria during long-term storage at low temperatures. Rancid taste occurs during long-term storage of milk in the cold, when under the action of lipase the fat undergoes profound chemical changes. Musty, cheesy and putrid tastes are the result of the development of peptonizing bacteria and E. coli bacteria. Viscous milk has a viscous slimy texture, as well as sour and other flavors. The defect occurs when milk is contaminated with lactic acid bacteria. Defects of technical origin appear as a result of a violation of milk processing technology. A metallic taste in milk occurs when using utensils that are poorly tinned or rusty. Products made from such milk quickly deteriorate during storage. Extraneous flavors and odors can be acquired by milk when using poorly washed and insufficiently dried dishes, when transported together with odorous products (onions, oil products, etc.). Defects of physical and chemical origin - changes in the composition and properties of milk that affect the technological conditions for the production of dairy products.

There are no bacteria in the milk of a healthy udder. Most of the bacteria enters the milk from the equipment and the udder of the cow (from the surface of the teats). During the first day, a cow with mastitis excretes mastitis bacteria abundantly, but their significance is small, because they do not multiply when milk is stored on the farm at a temperature of +1-4°C. If the number of bacteria in the milk has increased, then the cause is usually a failure to comply with the rules of machine milking or insufficient cooling temperature. Poor quality feed should not come into contact with the udder of the cow, so that bacteria during milking do not get from the udder into the milk.

If the harvesting technology is not followed, spore-forming bacteria are found in the feed. When feeding a low quality feed to a cow, they get inside without interference. In order to prevent the access of spore bacteria to the milk, the udder is thoroughly washed before milking, wiped with a damp cloth and thoroughly dried. The most common causes of milk taste are changes in milk fat and foods with a strong odor. A cow's milk before calving, at start-up and at the end of lactation can also have a strong taste.

The reason for changes in milk fat is faulty milking equipment, incorrect storage conditions, when not enough milk is at the bottom of the tank and it is mixed too quickly. If non-standard milk is obtained from a cow, for example, mastitis or from a cow before calving, then improperly configured equipment affects the composition of milk fat even more. It is advantageous to leave a cow undermilked when her productivity per day is 6 kg of milk. If the productivity is lower, the composition of milk changes and becomes non-standard: the content of somatic cells increases and taste deficiencies appear.

1.6 Factors that preserve the quality of drinking milk

The main factors that preserve the quality of goods are packaging, labeling, transportation, storage.

Containers and materials used for packaging and sealing the product must comply with the requirements of legislative, regulatory and technical documents that establish the possibility of their use for packaging dairy products.

Drinking milk is poured into glass bottles, paper bags with Tetra-Brik polymer coatings, plastic bags and other containers with a capacity of 0.25; 0.5 and 1 l. It is allowed to pour milk into flasks of various capacities and tanks. “Tetra-Brik” bags with milk should be packed in shrink films and stacked on pallets. The stacking of the transport package is carried out so that the marking of at least one unit of consumer packaging or packaging group is visible without their deformation.

Each unit of consumer packaging is marked with the following information:

Product name;

The rate of mass fraction of fat;

And an organization in the Russian Federation authorized by the manufacturer to accept claims from consumers on its territory;

Trademark;

Net volume of the product;

nutritional value;

Storage conditions;

date of manufacture;

Best before date;

The designation of this standard;

Product certification information.

The labeling of the transport packaging must contain the following information:

Product name;

Name and location of the manufacturer;

Storage conditions;

Best before date;

Gross weight;

Number of packaging units;

Designation of this standard.

Manipulation signs are applied to the transport container: “Keep away from sunlight”, “Temperature limitation” indicating the minimum and maximum temperature values.

Drinking milk is transported in closed refrigerated or isothermal means of transport in accordance with the rules for the transportation of perishable goods. When transporting milk, it must be protected from heating and freezing.

In accordance with the requirements of the technical regulation for milk and dairy products No. 88-FZ, milk and products of its processing intended for sale must be packaged, packaged in containers and (or) packaging made from environmentally friendly materials permitted by the federal executive body exercising the functions of control and supervision in the field of ensuring the sanitary and epidemiological welfare of the population, protecting the rights of consumers, for contact with food products and ensuring the safety and quality of milk and products of its processing during their shelf life. Milk-based baby food products for young children should only be produced packaged and packaged in sealed small-piece packages.

Milk is stored at a temperature of 0 to 8 0 C, relative air humidity not more than 80%, from 36 hours to 15 days. Depending on the modes of pasteurization and bottling; sterilized milk - from 10 days. up to 120 - 160 days. at a temperature of 20 0 C.

2. Study of the range and quality of drinking milk

2.1 Experiment setup and sampling procedure

The experiment was set up at the department of commodity science of food products. The rules for acceptance and the procedure for sampling for drinking milk are provided for by GOST 26809-86 “Milk and dairy products. Acceptance rules, sampling methods and sample preparation for analysis.

Milk is taken in batches. A batch is considered to be products made from the cream of one bath by converting high-fat cream, one batch - by the method of periodic churning, one container - by the method of continuous churning (the batch size should not exceed 40 boxes). Sampling was carried out after checking the condition of the container and establishing the homogeneity of the batch. Organoleptic indicators of milk and dairy products were evaluated separately for each controlled packaging unit. From each batch of milk packaged in Tetra-Pak bags, 1 package was taken as an average sample. The number of packages in each package is 12. The combined sample from each batch of milk was 12 consumer packages (packages).

The milk of each selected packaging unit was examined separately. The average milk sample, intended for determining physicochemical and organoleptic indicators, after mixing was brought to a temperature of 20 0 C. To determine the quality of milk samples, organoleptic indicators (taste, smell, appearance, consistency, color) and physicochemical indicators were determined ( density, acidity, mass fraction of fat, as well as a qualitative test for phosphatase). Milk processing is carried out immediately after milking. It is filtered and cooled to the lowest possible positive temperatures. Timely cooling of milk helps to prolong its storage.
The milk received at the dairy plant is checked for organoleptic characteristics, acidity and fat content. The received milk is purified from mechanical impurities, then the milk is normalized for fat, i.e., the fat content is reduced or increased, using low-fat milk or cream for this.

2.2 Objects of study.

To study the quality in the Perekrestok hypermarket, 5 samples of pasteurized drinking milk produced in accordance with GOST R 52090-2003 were selected: sample 1 Prostokvashino, OJSC Wimm-Bill-Dann; sample 2 - "Kuban Burenka" UNIMILK; sample 3 - "In the meadow" UNIMILK, sample 4 - "Merry milkman" JSC "Wimm-Bill-Dann", sample 5 - "Kuban milkman" CJSC "Cheese-making plant Leningradsky".

The characteristics of the marking data of the samples are presented in tables 1-5.

Table 1 - Labeling of drinking milk - sample No. 1 "Kuban Burenka"

Requirements GOST 51074 - 2003	Sample characteristic
Product name	"Kuban Burenka"
Name and location of the manufacturer
Mass fraction of fat
Trademark	Present
Product volume
The nutritional value
Storage conditions
date of manufacture
Best before date
Standard designation
Product Compliance Information	Present

The marking of this sample of milk "Kubanskaya Burenka" complies with the requirements of GOST 51074-2003 "Food products. Consumer Information". The storage periods have been met.

Table 2 - Marking sample No. 2 "In the meadow"

Requirements GOST 51074 - 2003	Sample characteristic
Product name	Drinking milk pasteurized "In the Meadow"
Name and location of the manufacturer	OAO Volgograd Dairy Plant No. 3 Unimilk Russia, Volgograd 20 Przhevalskogo street
Mass fraction of fat
Trademark	Present
Product volume
The nutritional value	Fat - 3.5 g, protein - 2.8 g, carbohydrates - 4.7 g. Calorie content - 58 kcal.
Storage conditions
date of manufacture
Best before date
Standard designation	GOST R 52090-2003 "Drinking milk OTU".
	Present

The labeling of this milk sample “On the meadow” complies with the requirements of GOST 51074-2003 “Food products. Consumer Information". The storage periods have been met.

Table 3 - Labeling of drinking milk - sample No. 3 "Prostokvashino"

Requirements GOST 51074 - 2003	Sample characteristic
Product name	Drinking milk pasteurized Prostokvashino
Name and location of the manufacturer	OAO Volgograd Dairy Plant No. 3 UNIMILK, Russia, Volgograd, st. Przhevalsky, 20
Mass fraction of fat
Trademark	Present
Product volume
The nutritional value	Fat - 3.5 g, protein - 2.8 g, carbohydrates - 4.7 g. Calorie content - 58 kcal.
Storage conditions
date of manufacture
Best before date
Standard designation
Product conformity assessment information	Present

The marking of this sample of milk "Prostokvashino" complies with the requirements of GOST 51074-2003 "Food products. Consumer Information". The storage periods have been met.

Table 4 - Marking of sample No. 4 "Cheerful milkman"

Requirements GOST 51074 - 2003	Sample characteristic
Product name	Drinking milk pasteurized "Happy Milkman"
Name and location of the manufacturer	OJSC "Wimm-Bill-Dann", Russia, Timashevsk, st. Hybrid, 2
Mass fraction of fat
Trademark	Present
Product volume
The nutritional value	Fat - 3.5 g, protein - 2.8 g, carbohydrates - 4.7 g. Calorie content - 58 kcal.
Storage conditions
date of manufacture
Best before date
Standard designation	GOST R 52090-2003 Drinking milk. OTU".
Product conformity assessment information	Present

The marking of this sample of milk "Merry Milkman" complies with the requirements of GOST 51074-2003 "Food products. Consumer Information". The storage periods have been met.

Table 5 - Marking of sample No. 5 "Kuban milkman"

Requirements GOST 51074 - 2003	Sample characteristic
Product name	Drinking milk pasteurized "Kuban milkman"
Name and location of the manufacturer	CJSC "Cheese-making plant Leningradsky"
Mass fraction of fat
Trademark	Present
Product volume
The nutritional value	Fat - 3.5 g, protein - 2.8 g, carbohydrates - 4.7 g. Calorie content - 58 kcal.
Storage conditions
date of manufacture
Best before date
Standard designation	GOST R 52090-2003 Drinking milk. OTU".
Product conformity assessment information	Present

The marking of this sample of milk “Kuban milkman” meets the requirements of GOST 51074-2003 “Food products. Consumer Information". The storage periods have been met.

Thus, all drinking milk samples contained complete information about the product in accordance with the requirements of the standard.

2.3 Research methods

2.3.1 Organoleptic indicators of the quality of drinking milk.

When organoleptically assessing the quality of drinking milk, the state of the package, appearance, texture, taste, smell and color are determined. The organoleptic evaluation of milk begins with an inspection of the packaging. Packages with dents, open seams, folds at the corners are noted.

When evaluating the appearance of milk, attention is paid to its uniformity and the absence of sediment. In reconstituted milk, a slight sediment is allowed.

There should be no dense fat globules on the surface of pasteurized milk. When shaking the milk, the fat accumulated on the surface should be easily distributed in it. High-fat milk should not contain cream sludge.

When determining the consistency, the milk is slowly poured from the bottle. The presence of floating lumps, settled cream indicates the heterogeneity of the milk consistency. By the sludge of cream, you can judge the freshness of milk. If the storage temperature is violated, the consistency of milk can be flaky, a white friable protein precipitate forms at the bottom of the container, and a clot forms as a result of an increase in acidity.

The taste and smell of milk is determined at room temperature, sometimes it is checked up to 37-38 0 C, since slight changes in taste and aroma are easier to catch.

The smell of milk is determined after shaking and immediately after opening the container, drawing in air. To determine the taste, take about 10 ml of milk, rinse the mouth with it to the root of the tongue and note the presence of deviations from the normal taste. It is not recommended to swallow test milk. Simultaneously with the taste, the smell of milk is determined.

To determine the color, milk is poured into a transparent glass and viewed in diffused daylight, paying attention to the presence of extraneous shades. To determine the quality of the selected samples of drinking milk, a comprehensive scoring of organoleptic indicators was used.

Weight coefficients of indicators are presented in table 6. Organoleptic indicators of milk quality appearance, color, taste and smell, consistency. Of these, the most significant are taste and smell.

The complex indicator is calculated by the formula:

Pk = ? (Sq x B), (1)

where Pk is a complex indicator, Kv is the weight coefficient, B is points.

Table 6 - Weighting coefficients of quality indicators

2.3.2 Determination of drinking milk quality indicators.

The determination was carried out according to GOST 3625-84 “Milk and dairy products. Density determination methods”. Essence of the method: The density of milk is determined by a hydrometer - lactodensimeter at a temperature of 10 to 25°C, bringing the instrument readings to 20°C. On the middle part of the device there is a scale with a division value of 0.001, indicating the density, in the upper part there is a thermometer scale.

Density varies depending on the content of the components of milk: with an increase in dry fat-free substances (SOMO), the density increases, with an increase in the fat content of milk, its density decreases, since the density of milk fat is less than water - 0.920.

When milk is diluted with water, its density decreases by about 0.003 for every 10% of added water. Milk with a density below 27 degrees lactodensimeter can be considered diluted with water. Thus, according to the density of milk, one can judge its naturalness. The aggregate state of milk fat also affects the density of milk - the density of hardened fat is higher than that of melted fat. To obtain comparable figures, the density of milk should be determined with the same physical state of the fat.

Method order. 250 ml of milk is heated in a water bath to 40°C and kept at this temperature for 5 minutes to transfer the fat to a liquid state, after which it is cooled to 20 ± 2°. The lactodensimeter is calibrated at 20°C, so when the milk temperature is close to 20°C, the determination is more accurate. To avoid the formation of foam, a thoroughly mixed milk sample is carefully poured along the wall into a dry cylinder, which at this moment should be kept in a slightly inclined position.

The cylinder with milk is placed on a flat horizontal surface and a dry and clean lactodensimeter is slowly immersed in it, after which it is left in a free floating state. The lactodensimeter must not touch the walls of the cylinder; the distance between its surface and the walls of the cylinder must be at least 5 mm. After 1 min after the lactodensimeter is installed in a stationary position, the readings of temperature and density are read.

During the reading of the density of the eye should be at the level of the upper meniscus. The density is counted along the upper edge of the meniscus with an accuracy of 0.005, the temperature - up to 0.05°C. The discrepancy between repeated density determinations should not exceed 0.005. If the temperature of the milk is above or below 20°C during the determination of the density, then the results of the reading are brought to 20°C according to a special table of milk density indicators. Each degree corresponds to a correction equal to 0.0002. At a milk temperature above 20°C, the correction is added; at a temperature below 20°C, it is subtracted. Determination of milk acidity was carried out according to GOST 3624-92 “Milk and dairy products. Titrimetric methods for determining acidity. The acidity determines the freshness of milk. The acidity of milk is expressed in Turner degrees. The acidity of fresh milk is due to the presence of proteins, phosphate and citrate salts, a small amount of dissolved carbon dioxide and organic acids in it. During the storage of milk, as a result of the development of microorganisms that ferment milk sugar, lactic acid accumulates and the acidity of milk increases.

Method order. Pipette 10 ml of well-mixed milk into a 100 ml conical flask, add 20 ml of distilled water and 2-3 drops of phenolphthalein. The mixture is thoroughly mixed and titrated with a 0.1 N burette. alkali solution with continuous shaking. First, about 1 ml of alkali is immediately poured, and then drop by drop until a faint pink color appears, which does not disappear within 1 minute.

...

Similar Documents

Trends in the development of the world milk market. Classification and characteristics of milk, its chemical composition, nutritional value and quality-forming factors. Evaluation of the assortment, organoleptic and physico-chemical indicators of drinking milk.

thesis, added 06/23/2015


Chemical composition and nutritional value of milk. Assortment of drinking milk and factors that shape and preserve its quality. Processes occurring in milk during storage. Commodity characteristics and analysis of the quality of milk samples from different manufacturers.

term paper, added 06/01/2014


Nutritional value, consumer properties of drinking milk, its range. Storage, transportation, labeling and packaging of milk. Analysis of the quality indicators of milk supplied for sale by AUCHAN LLC, assessment of its competitiveness.

term paper, added 01/04/2015


Nutritional value of milk product. Classification and assortment of milk. Technology for the production of drinking pasteurized milk with a fat content of 3.5%. Acceptance of milk, identification and examination of quality. Commodity processing, packaging and labeling.

term paper, added 11/20/2013


Classification and composition of milk, its types and features of the chemical structure. Properties and characteristics of milk, the quality of this product and the main factors affecting it. Signs of falsification. The study of indicators of the quality of milk of various brands.

term paper, added 09/30/2014


State and problems of the consumer milk market. The specificity of the chemical composition of milk. Factors that shape the quality of milk. Principles of classification and evaluation of the range of milk. Analysis of the range and quality of milk sold in the store "Maria-Ra".

term paper, added 10/03/2012


General characteristics of drinking pasteurized milk, its chemical composition and evaluation of nutritional value. The range and types of milk, the quality requirements of the raw materials used and the stages of the technological process of manufacturing the product. Defects and vices.

term paper, added 12/25/2014


A study of marketable drinking milk produced by UniMilk-Kemerovo LLC and sold in the Pensioner LLC chain of stores. Production range of drinking milk. Conducting surveys on marketing research of the consumer market.

term paper, added 01/16/2014


Chemical composition and nutritional value of milk. Factors that form and maintain its quality. Evaluation of the quality of milk by organoleptic and physico-chemical parameters in the trade hypermarket "Hippo". ABC-analysis of the range of pasteurized milk.

term paper, added 03/31/2015


Importance of milk in nutrition. Assortment of sterilized milk. Factors that shape the quality of sterilized milk. An assortment of sterilized milk sold in the food section of the Tsentralny department store. Examination of milk quality.

During the organoleptic evaluation of milk, the condition of the container, the appearance of the milk, its consistency, color, taste and smell are determined. :

When evaluating the appearance and consistency of milk, attention is paid to its uniformity, the presence of sediment, floating lumps and settled cream.

Color definition. Milk is poured into a transparent glass and examined for the presence of foreign shades.

Table 13 Sample No. 1 pasteurized drinking milk "Favorite" mass fraction of fat 2.5%

Conclusion on the organoleptic evaluation of sample No. 1 of pasteurized drinking milk “Lubimoe” with a mass fraction of fat of 2.5%, the package volume is 900 ml. complies with the requirements of GOST 31450-2013.

Table 14 Sample No. 2 pasteurized drinking milk "Luzinskaya Krynochka" with a mass fraction of fat of 2.5%

Conclusion on the organoleptic evaluation of sample No. 2 of pasteurized drinking milk "Luzinskaya Krynochka" with a mass fraction of fat of 2.5%, the package volume is 900 ml: meets the requirements of GOST 31450-2013.

Table 15 Sample No. 3 pasteurized drinking milk "Luzhaikino" with a mass fraction of fat of 2.5%

Index	Characteristics of indicators	Norms according to GOST	Conclusion
Consistency	Homogeneous, no sediment	opaque liquid	Corresponds
	Uniform throughout the mass	White, uniform throughout	Corresponds
	Characteristic for this milk	With a slight aftertaste of boiling	Corresponds
	No foreign odors	No foreign odors	Corresponds

Conclusion on the organoleptic evaluation of sample No. 3 of Luzhaykino pasteurized drinking milk with a mass fraction of fat of 2.5%, the package volume is 900 ml. complies with the requirements of GOST 31450-2013.

Table 16 Sample No. 4 pasteurized drinking milk "VNIMI-Sibir" with a fat mass fraction of 2.5%

Conclusion on the organoleptic evaluation of sample No. 4 of pasteurized drinking milk "VNIMI-Sibir" with a mass fraction of fat of 2.5%, the package volume is 900 ml. complies with the requirements of GOST 31450-2013.

Conclusion on the organoleptic evaluation of sample No. 5 of pasteurized drinking milk “Live Milk” with a mass fraction of fat of 2.5%, the package volume is 900 ml. complies with the requirements of GOST 31450-2013.

Table 17 Sample No. 5 pasteurized drinking milk "Live Milk" with a mass fraction of fat of 2.5%

Organoleptic indicators - appearance, color, smell, texture, taste - are determined by the senses (sight, smell, touch). The assessment of smell and taste is carried out by specially trained and certified experts. The smell and taste of milk are determined both immediately after sampling and after their storage and transportation for no more than 4 hours at a temperature of 4±2°C. The analyzed samples of milk are compared with a sample of milk without odor and taste defects. The assessment of smell and taste is carried out on a five-point scale (Table 18).

Table 18

High level
Average level
Below the average
non-standard

Comparative characteristics of samples of drinking cow's milk with a maximum fat content of 2.5% from different manufacturers. (Table 19).

Table 19. Comparative characteristics of drinking cow's milk samples with a maximum fat content of 2.5% from different manufacturers

Manufacturer's name	Name of product			Actual evaluation results
Producer CJSC "Lubinsky Dairy Plant", Russia, Omsk Region, Lyubinsky District, r.p. Krasny Yar, st. Congress, 10	Drinking milk pasteurized "Lubimoe"	Manufactured in accordance with GOST 31450-2013 from normalized cow's milk
	The consistency is liquid. Slightly viscous. Total 5 points.
Total: 20 points
Producer LLC "Luzinskoye Moloko", Russia, Omsk region, Omsk district, s. Luzino, st. 30 years of Victory, 16	Pasteurized drinking milk "Luzinskaya Krynochka"		Appearance - homogeneous opaque liquid.	Appearance - homogeneous opaque liquid. Total 5 points
Consistency - homogeneous, not viscous, slightly viscous. Free of protein flakes and lumps of fat.	The consistency is liquid. Slightly viscous. Total 4 points.
	The taste and smell are clean, without foreign tastes and odors, with a slight aftertaste of boiling. total 5 points.
Color - uniform, white with a slightly yellow tint	Color - white, uniform throughout the mass. Total 5 points.
Total: 19 points
Producer LLC "MilkOm" Russia, Omsk, st. Boundary 59	Drinking milk pasteurized "Luzhaikino"	Manufactured in accordance with GOST 31450-2013 from normalized cow's milk	Appearance - homogeneous opaque liquid.
Consistency - homogeneous, not viscous, slightly viscous. Free of protein flakes and lumps of fat.
Taste and smell - clean, without foreign tastes and odors, with a slight aftertaste of boiling
Color - uniform, white
Total: 20 points.
Producer LLC "VNMI-Siberia" Russia, Omsk, st. Red let 163.	Drinking milk pasteurized "VNIMI-Sibir"	Manufactured in accordance with GOST 31450-2013 from normalized cow's milk	Appearance - homogeneous opaque liquid.	Appearance - non-homogeneous opaque liquid with a slight sludge of fat. Total 3 points.
Consistency - homogeneous, not viscous, slightly viscous. Free of protein flakes and lumps of fat.	Consistency - homogeneous not viscous. Total 5 points.
Taste and smell - clean, without foreign tastes and odors, with a slight aftertaste of boiling	Taste and smell - pure, without extraneous smacks and smells. Total 5 points.
Color - uniform, white	Color is not uniform white. Total 4 points.
Total: 17 points.
Producer LLC "Kormilovsky molzavod" Russia, Omsk region, Kormilovsky district, r.p. Kormilovka, st. Factory, 15.	Drinking milk pasteurized "Live milk"	Manufactured in accordance with GOST 31450-2013 from normalized cow's milk	Appearance - homogeneous opaque liquid.	Appearance - homogeneous opaque liquid. Total 5 points.
Consistency - homogeneous, not viscous, slightly viscous. Free of protein flakes and tangled fat clumps	Consistency - homogeneous not viscous. Total 5 points.
Taste and smell - clean, without foreign tastes and odors, with a slight aftertaste of boiling	Taste and smell - insufficiently expressed - empty. Total 3 points.
Color - uniform, white	Color - uniformly white throughout the mass. Total 5 points.
Total: 18 points.
Manufacturer's name	Name of product	Characteristics of products in accordance with the requirements of regulatory documents (GOST, TU, Industry Standards, etc.)	Organoleptic indicators, according to the requirements of regulatory documents	Actual evaluation results

milk organoleptic competitiveness

Conclusion: Samples No. 1, No. 2, No. 3, No. 4 and No. 5 after the organoleptic evaluation are evaluated as excellent. The organoleptic evaluation of the quality of milk and dairy drinks showed that pasteurized drinking milk "Lubimoe", "Luzinskaya Krynochka", "Luzhaikino", "VNIMI-Siberia and "Live Milk" meet the requirements of GOST 31450-2013.

Shcherbaneva A., Varaksina Yu.

Project Manager:

Nikolaev Victor Valerievich

Institution:

MKOO "Serpomolotskaya secondary school" village Serp i Molot

In the presented research project in physics "Study of pasteurized milk with a fat content of 3.2%" the author studies theoretical information about milk, highlights the types of milk, its composition, and also reveals the differences between raw and pasteurized milk.

In the process of working on research project in physics "Study of pasteurized milk with a fat content of 3.2%" 7th grade students set a goal to determine experimentally which milk samples meet the requirements of GOST from the point of view of physics.

In the research work on physics "Study of pasteurized milk with a fat content of 3.2%", the authors raise the problem of adding impurities to milk, violations of production technology and milk selection procedures, which makes a healthy product useless, and sometimes even harmful to human health, and is looking for ways to solve it .

In the proposed project in physics "Study of pasteurized milk with a fat content of 3.2%" the authors conducted a number of experiments with milk, the process and results of which are systematized and presented in the form of tables, which can be viewed in the "Appendix" section.

Introduction
1. Theoretical information about milk.
1.1. What is milk. Types of milk.
1.2. Composition of cow's milk.
1.3. Physical properties of milk.
1.4. How and why dairy products are falsified.
1.5. Technology for the production of pasteurized milk.
1.6. Physical methods of combating the falsification of milk.
2. Experiments with milk
Conclusion
Bibliography
Application #1 - 7

annotation

“Drink, children, milk, you will be healthy!” - Probably, everyone knows the lines of this popular children's song. Milk and its derivatives are traditional components of everyday nutrition, both for adults and children.

However, in order to increase the amount of milk, the duration of storage and others, there is a fact of falsification of milk. As a result, it turns out that the “useful product” becomes “useless”. This paper considers several samples of pasteurized milk with a fat content of 3.2% for compliance with GOST.

The results of the study can be taken into account by consumers when buying pasteurized milk with a fat content of 3.2%.

Introduction

The human body needs a wide variety of food products, since it is mainly from them that it receives the nutrients necessary for life: proteins, fats, carbohydrates, vitamins, mineral salts, etc., which, in the process of assimilation, cover the body's needs for energy and materials for fabric construction.

Quantity, quality, range of food products consumed, timeliness and regularity of food intake have a decisive influence on human life in all its manifestations. That's why it's important to eat quality foods.

Milk has many health benefits and contains many nutrients. However, when delivering milk to commodity producers, deliverers can add impurities to improve its characteristics; when packaging, commodity producers can also falsify milk, departing from the production technology (GOST).

For example, adding lime (lime water), potash and soda to milk can increase the shelf life of milk, which is very beneficial when selling milk in stores. The reason for this is the greed of those who create the product.

We see a wide range of milk on the shelves when we come to the store. What to choose? This question is relevant in connection with the widespread consumption of this product.

Problem: adding impurities to milk, violation of production technology and milk selection procedures, make a useful product useless, and sometimes even harmful to human health, due to the wide range of goods, the question of choice arises.

Object of study: samples of pasteurized milk with a fat content of 3.2%.

Item: in taste, color, smell, consistency, density of milk, wetting with milk samples, the presence of impurities, the percentage of dilution with water. Hypothesis: different samples of milk have different density, degree of wetting, have impurities, different percentage of dilution with water, taste, color, smell, different consistency.

Target: to determine experimentally which milk samples meet the requirements of GOST from the point of view of physics.

Tasks to achieve the goal:

1. study the material on the topic under study;

2. to conduct experiments to determine the density, organoleptic indicators, the degree of wetting of milk samples on the surface of a solid body, the presence of impurities, to determine the content or absence of water;

3. analyze the received data and summarize.

Methods:

1. study and analysis of literature;

2. experiment;

3. filtering method;

4. organoleptic (sensory) method of food research.

5. method for determining the degree of wetting by the contact angle.

6. photographing method;

7. computer data processing method;

8. analysis and synthesis of the obtained data;

On a hot summer day, everyone is looking for salvation from the heat, for me this salvation is a glass of cool milk. But nowadays it becomes unprofitable to keep a cow in a personal farmstead - the feed is expensive.

You have to use milk bought in the store. The assortment of milk in the store is wide. By adding impurities to it, violating the production technology and the procedure for selecting milk, a healthy product can become useless, and sometimes even harmful to human health.

Milk is a very healthy and tasty product. It is not considered a drink, but a food. It can be used to protect the body from diseases, remove harmful substances. It is also used as a cosmetic remedy for dry skin.

When studying the literature on the research topic and GOST 13277-79, we determined the direction of our experiments, selected physical research methods. Having completed all the experiments, we made a conclusion on the compliance of GOST samples of pasteurized milk with a fat content of 3.2%.

We partially solved the problem, since we were studying three samples of pasteurized milk with a fat content of 3.2%. At the time of the study, three manufacturers of pasteurized milk with a fat content of 3.2% were represented on the shelves of stores in our district. The results of the study can be used by consumers when choosing milk.

Some stages of the study can be used in physics lessons. For example, an experiment to determine the density of milk by mathematical calculations can be used in a physics lesson in grade 7 on the topic “Density of matter”.