On the topic: Microbiological processes of spoilage of eggs and egg products. Microbiology of egg products

The microflora of eggs and egg products

Eggs consist of a shell, shells, white and yolk. The shell has pores with a diameter of 4-30 microns. On the surface of a freshly laid egg there is a layer of mucus, which, when dried, forms an epishell membrane (cuticle).

The contents of eggs obtained from healthy birds are practically sterile, and the surface of the eggs contains a small amount of microorganisms. This is due to the physiological mechanisms of protection of offspring: eggs have nonspecific immunity due to the presence of bactericidal substances in the protein (lysozyme, ovidin, ovomucoid, ovomucin, canalbumin.), high pH (9.2), antimicrobial resistance of proteins. Lysozyme acts on the cell membrane, is able to lyse or destroy most bacteria without lysis, mold fungi and yeast. Due to the presence of phagocytosis, bactericidal activity, the bird's oviduct is free from bacteria even though it opens into the cloaca. When eggs are laid, mucus remains on the surface of the shell, which includes lysozyme. This layer dries up and forms the epishell membrane - the cuticle, which has bactericidal properties for a short time.

Endogenous seeding eggs occurs as a result of diseases of birds, in which microorganisms enter the ovaries or oviducts, as well as due to the weakening of the physiological mechanisms for protecting offspring. Salmonella, pathogens of avian tuberculosis, BGKP, Proteus, Pseudomonas, staphylococci can endogenously enter the eggs.

Exogenous seeding eggs is due to the weakening of the bactericidal properties of eggs, as well as a massive dose of the causative agent of an infectious disease. The weakening of bactericidal properties is also associated with storage conditions. With prolonged storage under adverse conditions, lysozyme inactivation occurs, changes physicochemical characteristics egg contents, the pores become more permeable to microorganisms. Endogenous seeding is also facilitated by contamination of the shell with bird droppings, soil, bedding, as well as moistening of the egg surface. All of the above microorganisms can also enter eggs exogenously. Mold spores cannot penetrate through the pores of the shell, but when the spores germinate on the surface of the eggs, hyphae can penetrate through the shell

clogged pores clean eggs paraffin or mineral oil prevents the entry of microorganisms into the eggs. Detergents and disinfectants, as well as microbicidal gases, are used to remove microorganisms from the shell.

Types of egg spoilage. Under the action of microbial enzymes, the substances that make up the egg decompose with the formation of specific decay products. The most common egg defects are small spot, cuff and drying.

small spot appears as a result of the development of mold mycelium on the shell membrane. The color of the spot will depend on the type of microorganisms.

Cuff and dryer caused by putrefactive bacteria. The protein liquefies and acquires a greenish color, the yolk either collapses or dries to the shell membrane, and fetid gases form under the shell.

Rotting. Under the influence of proteolytic bacteria of the genera Pseudomonas, Staphylococcus, Proteus, Bacillus and others, putrefactive decomposition can occur with the formation of specific decay products. The contents of the eggs become green, pink, gray, black.

Eggs supplied for sale and industrial processing are subject to sanitary and veterinary examination. There must be a veterinary certificate of the well-being of the farm for contagious diseases of birds, an ovoscopy of eggs must be carried out. Eggs from disease-prone farms should be subjected to special handling or disposal. Of particular danger are waterfowl eggs, which are contaminated with salmonella, their sale in raw form is prohibited.

Microflora of egg products Frozen egg products and egg powders can be contaminated with various microorganisms during manufacture. Most often they can meet BGKP, proteus, bacilli, mold fungi. Salmonella may be present. During storage, egg powders can develop LSD, resulting in a sour and cheesy taste and smell.

Microflora of eggs and egg products - concept and types. Classification and features of the category "Microflora of eggs and egg products" 2017, 2018.

Eggs are a good nutrient substrate for microorganisms, as they have high nutritional and biological values. Fresh eggs from healthy bird, sterile. Sterile eggs remain for quite a long time and during storage. The reason for this is the presence of an immune substance in them - a specific protein lysozyme, as well as the fact that the egg shell, a film of dried mucus on it and shell membranes prevent the penetration of microbes.

However, with prolonged or improper storage of eggs, the activity of lysozyme gradually decreases, the physicochemical properties of their contents change, the integrity of the shells is violated, and the egg may undergo microbiological deterioration. The rate of spoilage of eggs depends on the storage temperature, relative humidity, shell condition, composition of microflora. The condition of the container and packaging material is of great importance. Eggs with dirty and damp shells spoil much faster than those with clean and dry ones.

Pathogens:

E. coli, staphylococci, mold fungi, butyric acid bacteria (clostridia), micrococci.

Sometimes eggs obtained from waterfowl contain salmonella. Salmonella-infected eggs can cause food poisoning. Therefore, the consumption of raw duck and goose eggs directly as food is limited, and it is prohibited in catering establishments. It is forbidden to use duck and goose eggs for the manufacture of confectionery products with cream, ice cream, mayonnaise, melange, egg powders. Such eggs are used in the production of confectionery, where they are exposed to high temperatures.

Damage types:

mold: mold fungi r. aspergillus, penicillium (raids of various shades). Compliance with storage rules.

rotting: Escherichia coli, Proteus, Staphylococcus aureus (turbidity, dark spots). Compliance with storage rules.

Melange

Melange- frozen mixture of protein and yolk. Melange can only be stored frozen. Melange usually contains a significant amount of various microorganisms, so thawed melange must be sold within a few hours, keeping it chilled.

egg powder

In the manufacture of egg powder by drying the egg mass, not all microorganisms (micrococci, staphylococci, salmonella, BGKP) die. When moistened or stored in a diluted form, this microflora quickly causes spoilage.

6. Microbiology of fats

Extraneous microflora that has entered fats from one source or another can cause a number of undesirable defects in taste and smell.

Damage types:

Rancidity: imperfect yeast (rancid taste and rotten smell). Compliance with the rules of storage and terms of implementation.

Mould: lactic acid bacteria, filamentous fungi (mold appearance). Compliance with the rules of storage and terms of implementation.

Sourtaste: fat arises as a result of its storage at temperatures above 10 ° C, when thermophilic lactic acid bacteria develop in it.

To protect fats from bacterial spoilage, preservatives are introduced into them that can inhibit the development of certain types of filamentous fungi, yeasts and bacteria. Benzoic acid, sodium benzoate, sorbic acid and sodium sorbate are used as preservatives. The amount of preservatives should not exceed 0.07-0.12%. An increase in their concentration leads to a deterioration in the organoleptic characteristics of fats.

From chicken eggs produce melange and egg powder.

Melange - a frozen mixture of protein and yolk, sold only in frozen form. It is necessary to store at a temperature of -5 ... -10 ° C, a shelf life of 10 months. Melange can also be made either from the yolk mass or in the form of egg white.

For the production of any type of melange, only high-quality eggs are used that meet the requirements of current regulations. specifications. Do not use duck, goose and limed chicken eggs, food defective eggs, as well as eggs from farms that are unfavorable for infectious diseases of birds.

Egg mixture usually contains a significant amount of various microorganisms. During manufacture, pathogenic and opportunistic bacteria can get into it. In the process of freezing and subsequent storage, the microorganisms in the melange partially die off, but can still be preserved. enough them, especially if the melange was not immediately frozen after manufacture. For example, the number of salmonella for 6 months. storage of melange can decrease by 1000, E. coli - by 100, total contamination - by 40 times. However, microorganisms never die completely.

Melange - perishable product, it is allowed to store it only in a frozen form. When thawing in the melange, microorganisms multiply intensively, so the thawed product must be sold within a few hours, keeping it chilled.

To reduce microbial contamination egg mixture sometimes, before freezing, they pasteurize for a short time (1-3 minutes) at relatively low temperatures (about 600), which do not change physical state melange. As a result of pasteurization, the contamination of the egg mixture is reduced by 90-95%. To increase the effect of pasteurization, it is recommended to add hydrogen peroxide (up to 1%) or substances that increase the pH of the mixture to 10-11 to the egg mixture before heating. Sometimes mixed with sugar in a ratio of 1:1. In saccharified melange, Salmonella die off already after 2-3 months at room temperature storage. In some cases, yeast, streptococci, clostridia are isolated from sugared and pasteurized egg melange.

Bacterial contamination of melange is normalized: the number of mesophilic aerobic and facultative anaerobic microorganisms (MAFAM) should be no more than 5 105 per 1 g of product; the presence of BGKP in the amount of 0.1 g is not allowed; Staphylococcus aureus and Proteus in 1g; salmonella should be absent in 25g.

Currently, the freeze-drying method is widely used. food products, at which 75 ... 90% of moisture evaporates in vacuum at a negative temperature.

Egg powder obtained by drying the egg mass by spraying it at 600C in special chambers. To do this, use chicken table eggs (except for limed ones) and egg frozen melange that meets the relevant requirements. Properly prepared egg powder absorbs water well and has the properties of fresh eggs. Benign egg powder has a light yellow color, taste and smell characteristic of a dried egg. The advantages of egg powder are reduced volume and weight, the ability to store in an uncooled room, and good transportability.

Drying only kills part of the bacteria. In egg powder, spore-forming bacteria, staphylococci, streptococci, Escherichia coli, and sometimes salmonella are found in a viable state. During storage, the microflora gradually dies off.

The shelf life of egg powder at a temperature not higher than 20 ° C and relative humidity not higher than 75% is about 6 months; at a temperature of 2 ° C and below and a relative humidity of 60-70% - up to two years.

The quality of egg powder is evaluated by the same microbiological indicators as melange. If the titer should not be lower than 0.1 g.

Sanitary and microbiological studies of egg products and eggs are carried out under the control of poultry farms food production, as well as in the presence of epidemiological and epizootic indications. If pathogenic microorganisms are found in egg products, then such products cannot be used for food purposes.

Sanitary and microbiological control is subjected to incoming raw materials (chicken eggs), finished products: egg melange, egg powder, as well as monitoring compliance with technological and sanitary-hygienic regimes for the production of egg products.

Eggs for microbiological analysis are selected from different places of the batch by random sampling in the amount of 30 pieces (in some cases, at least 5-10 eggs). The selected sample is packed in a clean container and transported under conditions that exclude their damage and secondary contamination (contamination).

A feature of the sanitary and microbiological study of eggs and their products is the simultaneous study of the microflora on the surface of the shell and the contents of the egg.

In the microbiological examination of the surface of the egg shell, swabs are made, obtained by a) the swab method or b) the rinsing method or c) the grinding method.

When a wash is obtained using a swab, the egg is immersed in a mortar containing 10 ml of sterile saline and the surface of the egg is washed with a sterile swab for 2-3 minutes, the resulting wash is examined.

When receiving flushing by rinsing into a sterile dish or plastic bag pour 10 ml of sterile liquid into which the egg is immersed and shaken for 5 minutes. The resulting wash is examined.

Upon receipt of the flush by grinding, the shell and shell membrane of three eggs are separated from the contents and placed in sterile mortars. The contents are ground with a pestle, pour 90 ml of sterile liquid. After 3-5 minutes of settling, the supernatant is examined without dilution or tenfold dilutions are prepared, depending on the degree of contamination of the shell surface.

The total bacterial contamination of the egg surface (i.e., the amount of MAFAnM) is determined by conventional methods by inoculating 1 ml of the wash or its 10-fold dilutions in parallel into two Petri dishes, which are poured into 15 ml of MPA melted and cooled to 500C, cultivated at 300C. in a thermostat for 48-72 hours. All colonies that have grown in depth and on the surface of a dense nutrient medium are counted, the arithmetic average number of colonies is determined for two cups of one dilution, multiplied by the dilution value and divided by the surface area of ​​the egg shell. As a result, the number of microorganisms (CFU/cm2) per 1 cm2 of eggshell is obtained.

Before microbiological examination of the contents of the eggs, the surface of the shell is washed with a warm 0.2% solution. caustic soda or 0.5% soda ash solution for 2 minutes. Rinse the egg after washing tap water, allowed to drain and immersed in 70% alcohol for 10 minutes, after which they are burned in a flame.

On sharp end eggs make a hole with a diameter of about 1 cm and fire again, the contents of one or more eggs are poured into a flask and homogenized with beads or pipettes until uniform consistency. The study is carried out immediately, for this, 10 ml of the egg mass is transferred into a flask containing 90 ml of sterile saline - this is the initial dilution of 1:10, from which 1 ml is transferred into a test tube with 9 ml of saline, obtaining a dilution of 1:10, 1:100, etc. to the desired final dilution.

Microbiological examination of the contents of the eggs is reduced to the determination of MAFAnM, the identification of BGKP, Staphylococcus aureus, Proteus, Salmonella, in some cases B.cereus.

To determine MAFAnM (CFU/g or CFU/ml), 1 ml of the obtained dilutions is added in parallel to Petri dishes (2 cups for each dilution) and poured into the molten and cooled to 450C MPA. Thoroughly mix, after solidification, incubate at 300C for 72 hours. All grown colonies are counted, and the arithmetic mean of the number of colonies from all inoculations of one dilution is determined from the counting results.

The number of CFU in 1 g of egg products is determined by the formula:

X \u003d A x 10n / V

where A is the arithmetic mean of the number of colonies in the cup; n is the degree of tenfold dilution of the product; V is the volume of inoculum applied to the cup. The research results are recorded as follows: the number of mesophilic aerobic and facultative anaerobic microorganisms is 1.0 x 10 CFU / g.

To identify BGKP, culture is carried out in 1 ml natural product, and from dilutions of 1:10, 1:100 in Kessler's medium, the crops are cultivated for 24 hours in a thermostat at 370C. Test tubes with signs of growth are inoculated on Endo medium and incubated for 24 hours at 370C. Then the crops are viewed and the growth of colonies characteristic of CGB is noted, preparations are prepared from at least three characteristic colonies, Gram-stained and microscoped. The results are evaluated for each sample separately. Detection on Endo medium of colonies with characteristic features growth, the presence in smears of gram-negative lactose-fermenting rods indicates the presence of CGB in the product.

The result is recorded as follows: not detected (or detected) CGB in 0.1 ml of liquid (in 0.1 g of dry) egg products.

To indicate salmonella, 25 ml of a natural product is added to a flask containing 225 ml of enrichment medium (Kaufman, magnesium or selenite), shaken, thermostated at 370C for 20 hours. The results are recorded on the ICA after 48 hours, and on the Ploskirev, Levin media - after 24 hours. At least three colonies typical of Salmonella are taken and inoculated into test tubes with MPA, MPB, and Krumvide-Olkenitsky or Kligler differential medium). Krumvide-Olkenitsky or Kligler media are inoculated with a stroke on a sloping surface, and then with an injection into the depth of the column. The cultures are incubated in a thermostat at 370C for 24 hours.

The grown colonies from the surface of the differential media are used for setting up RA and preparing smears. The resulting cultures are studied for morphological, tinctorial, enzymatic properties, the ability to form hydrogen sulfide and other properties characteristic of bacteria of the genus Salmonella.

Microbiological indicators of eggs and egg products regulated Sanitary regulations and norms are presented in table 9. egg microbiological contamination of microflora

Table 1 Standards for microbiological indicators of eggs and egg products

Additional material.

During the microbiological examination of frozen egg products (mélange, protein, yolk), to check the quality of frozen egg products with the requirements of the current regulatory and technical documentation, 3% of the boxes, but not less than six, are selected from different places of the batch. From the total number of selected boxes, one package, a can, is selected from each box selected in the sample. From different places of each package, jars are taken with a sterile oil probe at least four columns of the product into a sterile dish. Before microbiological examination, the samples are thawed in a water bath at a temperature not exceeding 450C to a temperature inside the product not higher than 1-50C.

The selected samples are combined, thoroughly mixed and a combined sample weighing no more than 0.5 kg is obtained, which is placed in a sterile container with a ground stopper. 100 g of the product is taken from the combined sample for microbiological analysis, the rest is used for organoleptic and physico-chemical methods of analysis.

To assess the sanitary and microbiological quality of dry egg products, 3% of the packaging units, but not less than 3 units, are selected from different places of the batch under study. At least three point samples taken in equal numbers are taken from different places of the packaging unit selected for the sample.

Sampling is carried out with a probe, scoop, spoon, metal tube, spatula or other device, which each time before use is sterilized by flaming or in advance in an autoclave.

The mass of the sample taken from each barrel, bag, box or jar should be 200 g. From a batch of dry egg product packed in bags, three bags are taken from different places in each box selected in the sample. The samples are combined, thoroughly mixed, quartered and a combined sample weighing 0.5 kg is obtained.

The combined sample of egg powder is divided into two equal parts, which are placed in clean sterile glass jars with ground stoppers or plastic bags.

One part of the sample is sent to the laboratory for research, the other is sealed, labeled and stored for one month at a temperature not exceeding 200C and a relative humidity of 65-75% in case of disagreement when determining the quality of a dry egg product. On the label indicate: the name of the manufacturer; Product name; production date; lot number and size; date and place of sampling; the name of the person who took the sample; designation of the current regulatory and technical document.

100 g of dry egg product is taken from the combined sample into a sterile container for analysis, the rest of the sample is used for organoleptic and physico-chemical analyzes.

To prepare dilutions, a weighed portion of dry egg products weighing 10 g is added to a flask with 90 ml of sterile saline, following the rules of asepsis, and a series of tenfold dilutions of egg products is prepared, depending on the expected contamination of the product.

If the quality of eggs and egg products does not match according to microbiological indicators, they are sent to the production of heat-treated products.

Bird eggs for their nutritional and taste qualities occupy one of the most important places among human food products, due to the diversity and usefulness of the nutrients they contain.

At present, the production of egg melange has become widespread, which is used mainly in Food Industry(confectionery, pasta, bakery, etc.). Also produced in large quantities highly nutritious concentrated product - egg powder. Fertilized eggs are used in the manufacture of vaccines against certain human and animal diseases. bird eggs are a valuable raw material for the production of many industrial products as well as pharmaceuticals.

Egg waste when adding 20% ​​to them table salt used in the tanning of hides High Quality. Egg white is used to give the furs shine, and the yolks - elasticity to the skins.

The use of egg white in the printing industry improves image clarity and is used in card printing. Egg white is used in the manufacture of high-quality paints, and adding it to ordinary sales paints gives pictures and tables a shine. Egg white is used as an antidote for poisoning with arsenic and heavy metal salts.

Veterinary and sanitary requirements for the collection and storage of eggs

The quality of eggs depends on the sanitary and hygienic conditions for keeping laying birds, the conditions for storing and transporting eggs. It is recommended to choose eggs from the nests as often as possible in order to prevent their pollution, as well as strong cooling in cold weather and overheating in hot weather. Nests should always be kept clean, as contamination of eggs contributes to their rapid deterioration. Eggs should not be shaken, as this may cause the hailstones to break and the yolk to move towards the shell. Dirty eggs should not be washed or wiped, as this does not improve their quality, but, on the contrary, they undergo rapid deterioration. Soiled and moistened eggs must be laid out in one row and dried, and then put in a container separately from clean eggs. IN warehouses temperature fluctuations should not be allowed, since cold eggs, falling into conditions of more high temperature sweat, and this contributes to their rapid deterioration.

Packing and transporting eggs

Eggs are packed separately by types and categories in standard boxes of 1440, 720 and 360 eggs, as well as in corrugated boxes of 180 eggs. When packing eggs in wooden boxes as packaging material spruce or fir shavings are used. Containers and chips must be dry and clean. You can not pack eggs in sawdust, bran, chaff, as these materials contribute to the deterioration of eggs.

When transporting eggs during frosts, they are packed in insulated boxes with double walls and covered with straw mats. In the raw rainy weather boxes with eggs must be covered with a tarpaulin. Carrying boxes with eggs, as well as raising and lowering, must be done very carefully to avoid breaking the hailstones.

Egg microflora

Eggs can be seeded with various microflora. The degree of seeding them depends on the conditions of keeping and feeding the birds, the state of her health, the contamination of the shell, the quality of collection, transportation and storage time of the eggs.

Eggs are seeded with microflora in endogenous and exogenous ways. Endogenous seeding occurs in the ovary and in the oviduct of laying birds of patients or carriers of pathogens of paratyphoid, pullorosis, typhoid fever, tuberculosis, as well as with beriberi A, polyavitaminosis, etc.

Exogenous seeding of eggs is facilitated by contamination of the egg shell with bird excrement or earth and moistening of the shell. When storing eggs under conditions elevated temperature Motile bacteria and mold fungi, whose mycelial filaments easily push apart the mesh base of the shell membranes, relatively easily penetrate into the contents of the egg. Eggs with moist shells spoil almost 9 times faster than clean eggs. Storing eggs in a warm and dry room contributes to their rapid shrinkage, and with high humidity in storage rooms, they are affected. fungi.

It should be noted that in fresh eggs the penetrating microflora is gradually inactivated in the protein.

If, however, colloidal changes occurred in the protein under the influence of aging, expressed in the partial liquefaction of the dense protein and in the transformation of the spherical shape of the yolk into an ellipsoid (lowering the yolk index), then the bacteria, together with the water released during the liquefaction of the protein, penetrate into the yolk and linger in it. In cases where laying birds are affected by avitaminosis A or polyavitaminosis, the bactericidal and bacteriostatic properties of egg white are sharply reduced and the eggs quickly deteriorate.

The rate of penetration of microflora from the shell into the albumen and then into the yolk depends on the hygienic condition of the nests for laying eggs, on the temperature and humidity of the air in the storage facilities, storage and transportation conditions, as well as on the type of microorganisms living on the eggshell. Pathogenic microorganisms (mycobacterium tuberculosis, salmonella, etc.) do not cause noticeable organoleptic changes in egg yolk and protein. With the penetration of proteolytic microorganisms into the eggs, rotting of the eggs gradually occurs.

Examination and sorting of eggs into categories

For determining general condition and grade of eggs, 10% of the packaging units from the entire batch are opened, and 50 eggs are taken from each unit for candling. When determining the good quality of eggs, attention is paid to their freshness and the condition of the shell. With prolonged and improper storage of eggs, the shell loses its matte color and becomes shiny. Most eggs have an enlarged air chamber. However, the main feature that characterizes the age of the eggs is the increase in the volume of the yolk and the liquefaction of the dense albumen. If the yolk is invisible during translucence of fresh eggs due to the large layer of gelatinous protein surrounding it, then in old eggs the yolk has sharply defined boundaries, it is located near the shell and is highly mobile. When opening old eggs and pouring them onto a smooth surface, a watery white and a flattened yolk are found.

The freshness of eggs is determined by transillumination on an ovoscope. When candling, attention is paid to the transparency of the egg, the visibility and mobility of the yolk, and the size of the pug. In case of detection of spoiled eggs and various anomalies, the entire batch of eggs is subjected to ovoscopy and, as a result of the inspection, a conclusion is made about their quality. When examining eggs, the condition of the shell, the size of the puga, the condition of the protein and yolk are taken into account.

Eggs with clean shells and uniform in freshness are sorted by weight on a special machine. Sorting on the machine allows you to skip up to 4500 eggs per hour and distribute the eggs into five weight groups. According to MRTU 46-2-66, chicken eggs are sorted into dietary, fresh, refrigeration and limed.

Dietary eggs include eggs that have reached the consumer no later than 5 days after they were laid. Fresh eggs that do not meet dietary requirements and have been stored in proper storage conditions at a temperature not lower than 2 C or in refrigerators for no more than 30 days. Refrigeration eggs include eggs that have been in refrigerators for more than 30 days, limed eggs - eggs stored in lime mortar.

Dietary eggs, depending on the mass, are of two categories: Category I - selective, eggs weighing at least 58 g each; Category II - egg weight not less than 44 g. Dietary eggs must have a clean and strong shell, a fixed pug no more than 4 mm in size, the yolk is strong, barely noticeable, occupies a central position in the egg, the germinal disc is invisible. An indelible brand is placed on the shell of each dietary egg.

At the poultry farm (on farms) each diet egg branded with indelible paint: I category - red, II category - blue.

Fresh eggs differ from dietary ones in terms of weight and more long term storage. They are also divided into two categories: I and II.

Fresh eggs of category I must have a clean, strong and whole shell, a fixed air chamber. Strong, inconspicuous yolk, which occupies a central position in the egg; the protein is dense, translucent. The height of the pug is not more than 11 mm. The mass of one egg must be at least 47 g.

Fresh eggs of category II must also have a clean, strong and whole shell, slight contamination in the form of individual points is allowed. The puga is easy to move and can be up to 13mm high. The yolk is weakened, clearly visible when the egg is translucent. The mass of one egg is not less than 43 g.

Chicken eggs that have all indicators of good quality, but weighing less than 43 g, are defined as small and sent to the network Catering or for industrial processing.

Eggs with contaminated shells form a special group. They are packed in a separate container with the label "Dirty shell". Contaminated shells significantly reduce the shelf life of eggs, so such eggs are sent for immediate sale in the bakery or confectionery industry.

Sanitary assessment of eggs in case of defects

Distinguish between food and technical defects of eggs

Food defects include: lightweight eggs - weight less than 40 g; eggs with a pug more than a third of the egg high; notch - cracked shell; crumpled side - crumpled shell without damaging the shell; pouring - partial displacement of the protein with the yolk; small spot - the presence of mold colonies under the shell up to "/ on the surface of the egg; small dryness - the yolk touches the protein shell in a small area, is mobile; odor - a foreign smell; contaminated shell. Eggs with defects are sent for immediate sale.

Technical defects of eggs: black rot (tumak) - occurs as a result of penetration of microbes (Proteus) into the egg, the egg is translucent during ovoscopy and looks black; krasyuk - rupture of the yolk membrane and mixing of the yolk with protein; blood ring - development blood vessels around the embryo large dryer - the yolk has dried up to the shell in a large area; a large spot - the presence of mold colonies on the shell membranes larger than 1/8 of the egg surface. Eggs with such defects are sent for technical disposal.

Use of eggs from farms disadvantaged by infectious diseases

Eggs from farms that are unfavorable for tuberculosis, salmonellosis, ornithosis are neutralized by boiling at a temperature above 100 C for 13 minutes. After boiling, such eggs can be stored for up to five days at a temperature of 0-3 C. Salmonella have significant heat resistance. When boiling soft-boiled eggs, making scrambled eggs, omelettes, puddings and when using them for others culinary products complete neutralization of salmonella does not occur. in bakeries and confectionery baked at temperatures above 100 C, salmonella and mycobacterium tuberculosis are completely inactivated.

Considering that waterfowl are more likely to suffer from salmonellosis, it is forbidden to use duck and goose eggs in the catering network. Waterfowl eggs may only be used in bakeries and confectionery enterprises for the manufacture of flour products requiring high heat treatment. It is not allowed to pack and store duck and goose eggs with eggs of other poultry. They should be packed in separate boxes with a stenciled inscription "Duck eggs", "Goose eggs" with the indication "For bakery industry". In veterinary certificates drawn up for a batch of duck or goose eggs, the date of packaging and shipment of them must be indicated.

Egg products (melange) are frozen or dried into powder. When thawed, melange deteriorates extremely quickly, and microflora intensively reproduces in it. Therefore, in the production and use of melange, it is necessary to strictly observe sanitary and hygienic conditions. The production of egg melange consists of the following operations. After removing the marriage, the eggs are disinfected, then, observing the strictest cleanliness, they are broken. The contents of the eggs freed from the shell are passed through a rotary pump, where the albumen and yolk are mixed and filtered to separate particles of the shell, hailstones and shell membranes. After that, the egg mass is mixed in a special mixer, poured into cans, sealed, frozen and stored in the refrigerator. By order of the food industry can be prepared separately egg yolk and protein.

Laboratory work. Ovoscopy of eggs in order to identify grade and various kinds egg marriage. Familiarization with the current regulations for the use of waterfowl eggs.

Control questions. Classification of commodity eggs. Veterinary and sanitary requirements for the collection and storage of eggs. Eggs as a possible source of human infectious diseases. Vetsanekspertiza of eggs obtained on farms disadvantaged for infectious diseases.

A freshly laid egg from a healthy bird is usually free of microorganisms. The sterility of eggs remains for a long time during storage, this is due to the presence of natural immunity: the shell protects against the penetration of microbes, and the lysozyme contained in the egg has the ability to dissolve and kill many microorganisms, especially gram-positive ones. With prolonged storage, the egg dries out, lysozyme is gradually inactivated.

The seeding of eggs with microbes is possible in an endogenous and exogenous way.

Endogenous seeding occurs during the formation of eggs in the ovary and oviduct of laying hens with salmonellosis (pullorosis), avian tuberculosis and other infectious diseases.

Exogenous seeding of eggs occurs upon contact with the droppings of bacteria-carrying birds, under unsanitary conditions for obtaining and storing eggs. The rate of penetration of microbes through the pores of the shell into the egg is influenced by the environment: temperature, humidity, the degree of freshness of the eggs and a decrease in the activity of lysozyme. At low storage temperatures, the rate of penetration of microorganisms slows down, but psychrophilic species pass through the pores of the shell even at zero temperature.

Egg rotting - the process of splitting complex nitrogen-containing organic compounds (mainly proteins) by microbial enzymes. Egg rot is one of the most common malformations of bacterial decay. In the initial stage of spoilage, microorganisms form isolated foci on the surface of the shells in the form of individual colonies. When putrefactive microbes multiply in the egg, it becomes spoiled, a significant amount of gases sometimes exploding the shell accumulates inside the egg. In some cases, the contents of the egg acquire a gray-green color and emit strong smell hydrogen sulfide, during bacteriological examination, Pseudomonas, Serratia, E. coli, Micrococcus, Staphylococcus and Proteus are released, diluting the contents of the egg and staining it dark.

Molding of eggs. The surface of the shell, when stored in unsanitary conditions, becomes contaminated with various bacteria, mold fungi, actinomycetes, etc. When eggs are stored in conditions of high humidity, the hyphae of microscopic fungi penetrate inside and form a branched mycelium that fills the entire protein cavity, which is detected in the form of a dark spot during ovoscopy. Fungi of the genus Penicillium, Aspergillus, Cladosporium and Mucor are more often isolated from mold fungi.

Eggs with defects of bacterial and mold origin are subject to disposal or destruction.

egg-borne infections are often common to humans and birds. Bacteria of the genus Salmonella are the most dangerous to humans. Infection of eggs with these bacteria for the most part associated with salmonellosis of birds, which are most common among waterfowl and are caused mainly by S.typhimurium, and in chickens by S.gallinarum, S.pullorum, etc.

Infection of birds with salmonella occurs through food, water and environmental objects. The disease affects mainly young animals, in which salmonellosis is acute and is characterized by a high percentage of death. In adult birds, the latent form is more common, which is especially dangerous, since infected birds become bacteria carriers, from which endogenous infection of eggs and livestock buildings occurs. However, the introduction of bacteria into an egg laid by healthy animals can also occur after laying, if the egg is contaminated with the droppings of bacteria carriers, i.e. Infection of eggs with Salmonella can occur both endogenously and exogenously.

In order to prevent food poisoning, duck and goose eggs, as well as chicken eggs from farms that are unfavorable for tuberculosis, are allowed to be used only in well-baked dough products or hard-boiled ones (boil for at least 13-14 minutes). To prevent pollution food enterprises waterfowl eggs should be processed in a separate room with subsequent disinfection.

Egg storage. Egg sterility is preserved long time However, during prolonged storage, its pH rises, lysozyme is gradually inactivated, the egg dries out, the consistency of the protein changes, the yolk becomes mobile, and conditions are created for the penetration and reproduction of microorganisms in the egg. To slow down the aging process, eggs should be stored in cool, dry rooms.

Along with the physical, there are also chemical qualitative changes. You can slow down spoilage up to six months by storing eggs at 2 0 C and 85% humidity. To determine the freshness of eggs, candling is used: fresh eggs they transmit light well, in old eggs the air chamber (puga) is enlarged, and the contents become darker.

egg canning is the creation of unfavorable conditions for the reproduction of microorganisms. For canning eggs intended for long-term storage dry melange is used to obtain egg powder or freezing.

Drying the egg mass to obtain egg powder is carried out according to the following method. Eggs selected after candling are washed, disinfected, and then broken and freed from the shell. Further, to obtain melange, the yolk and protein are crushed, mixed and filtered to separate shell particles, fibers and films. The resulting melange enters the drying chamber on a rapidly rotating disk, the air temperature in the egg mass spraying zone is about 50 0 С. Therefore, the amount of moisture in the resulting mass should be reduced to 5-9%, which will delay the development of the remaining microflora. Egg powder is packaged in tin cans with parchment lining and stored at a temperature not exceeding 15 0 C.

Egg powder is to be consumed only after a heat treatment that ensures sufficient sterilization.

for transportation and long storage Their eggs are often turned into the so-called melange (mixture), which is a mixture of frozen proteins and yolks; only high-quality chicken eggs are used for freezing. To reduce the bacterial contamination of the melange, the eggs selected after ovoscopy are washed, disinfected, and then broken and freed from the shell, the protein and yolk are mixed, filtered, poured into cans, sealed and frozen. The resulting frozen mixture is stored at a temperature of minus 5-10 0 C. Although the contents of the eggs were sterile, the finished melange contains a significant amount of microorganisms (hundreds and even millions in 1 g). The melange may contain E. coli, Staphylococcus, Proteus and aerobic bacilli, which multiply rapidly after defrosting, so the melange should be thawed only before use so that the remaining microflora does not have time to become active.

Melange, which has good organoleptic characteristics with a coli-titre of at least 0.1 ml, in the absence of pathogenic microbes in it, is allowed for the manufacture of all products that, according to technological conditions production must be subject to heat treatment under pasteurization conditions.

Considering the particular risk of development of pathogenic bacteria and the occurrence of food poisoning, it is allowed to use only clean whole eggs for the preparation of creams. To do this, until the shell is destroyed, it is recommended to immerse the eggs in a solution of ammonia silver 1: 20,000 for 15 minutes or a 2% solution of bleach for 5 minutes, followed by immersion in a 2% solution of bicarbonate of soda (NaHCO 3) and subsequent washing with water.

Melange is prepared only from chicken eggs and is used only in food industry enterprises; melange is not available for free sale to the population.