Section yi. Microbiology of meat, meat products, production control of meat and meat products

After slaughter, with the termination of the life of the animal, the composition and properties of tissues change.

The reason for these changes are biochemical and physico-chemical processes occurring under the influence of tissue enzymes.

The state of the meat changes, it ripens.

Ripe meat has a tender texture, juiciness, pleasant taste and aroma.

The maturation of meat is an enzymatic process. In the process of cooling the meat, glycogen breaks down with the formation of lactic acid. It should be noted that in meat from lean and sick animals, the content of lactic acid is 2.5-3 times less than in the meat of well-fed and healthy animals. It is known that lactic acid contributes to the resistance of meat to putrefactive microbes and hence its preservation.

SOURCES OF CONTACT OF MICROORGANISMS IN MEAT.

Meat from healthy cattle, slaughtered after adequate rest, can be practically considered germ-free.

The meat of patients in the dying state and overworked animals contains aerobic and anaerobic microorganisms. There is a so-called endogenous or intravital contamination of meat with microbes.

At the time of slaughter, the meat is seeded with microbes, and often quite strongly. This is the so-called exogenous seeding. There are many microbes on the knife blade and at the time of slaughter they enter the blood vessels and are sucked into the heart and tissues with blood.

During the period of removal of the viscera (guts), there may be contamination with the contents of the gastrointestinal tract.

The skin of an animal contains many microorganisms, and when it comes into contact with it, the meat becomes contaminated. There may be cocci, sarcins, bacteria of the intestinal group, fungi, bacilli.

Carcass toilet. After skinning, the toilet of the carcass is performed - washing with water t= 38 - 40 o C, under pressure.

If ante-mortem cleaning and washing of animals is used, the toilet of the carcass is eliminated. Dry processing of carcasses is used - pollution is removed without the use of water.

On meat carcasses ax, a diverse microflora is found: bacteria of the intestinal group, proteus, spore-forming ammonifiers, fungal spores, streptococci, etc. (E. Coli, Proteus vulgaris, Bac. Subtilis, Bac. Merentericus, Cl. Sporogenes, Cl Putrificum, etc.).

DISTRIBUTION OF BACTERIA IN MEAT.

Microbes get deep into the meat along the fascia, bones, blood vessels. The rate of penetration of microbes depends on the temperature of the meat and the type of microorganisms.

Yes, at room temperature microbes from the surface penetrated 3 cm into a piece of meat weighing 2 kg., and at 37 o C were found in the whole piece. Or, for example, salmonella penetrated to a depth of 14 cm, and saprophytes - only 4-5 cm under the same conditions.

Under favorable conditions, microorganisms continue to multiply and cause spoilage of meat.

Microorganisms multiply especially rapidly in poorly bled meat.

Temperature, as noted above, also plays an important role in microbial reproduction. The lower the temperature, the lower the rate of microbial reproduction.

pH indicator. With its decrease, the development of putrefactive microbes stops, which happens when meat ripens - the accumulation of lactic acid in it.

FOOD TOXIC INFECTIONS AND TOXINS.

The cause of human poisoning caused by poor-quality meat products are microorganisms and their toxins.

A characteristic feature of meat poisoning is the suddenness of the onset, the mass nature of the disease after consuming the same product.

Poisonings caused by microbes are divided into two groups: toxicoinfections and toxicosis.

Toxic infections are caused by microbes that enter the body, which break down with the release of toxins. With toxicosis, only toxins enter the body.

Toxic infections, for example, are caused by Salmonella, Proteus, Escherichia coli, Staphylococcus aureus. Toxicosis - a toxin of the causative agent of botulism, staphylococcosis.

The ways of getting microorganisms into the meat are very diverse: endogenous and exogenous, as already mentioned above. It should be noted the role of people suffering from certain diseases, as well as the possibility of seeding meat with rats, mice, flies.

Of the dangerous toxic infections, salmonellosis should be noted. Salmonella often gets into the meat during life, because they are the causative agents of the infectious disease of young animals - salmonellosis.

Therefore, meat is examined for the presence of salmonella, especially a thorough and mandatory examination of meat from cut animals.

Toxic infections can be caused by the so-called. Conditionally pathogenic microorganisms - E. Coli, Proteus vulgaris, streptococci, staphylococci, etc.

One of the severe toxic infections is botulism. Previously, it was believed that only the toxin causes poisoning. It turned out that the causative agent of botulism itself can be the cause of poisoning.

Poisoning occurs when using low-quality sausages, ham, canned food, smoked fish.

Prevention of food poisoning. The main thing: strict veterinary and sanitary supervision over the slaughter of livestock, the processing of meat and meat products, as well as their culinary processing.

MEAT AS A POSSIBLE SOURCE OF DISEASE IN HUMANS AND ANIMALS.

Meat from animals with infectious diseases can be a source of the pathogen.

With a number of diseases, meat is forbidden to be used as food, and it is destroyed. In other diseases that are dangerous only for animals, such as swine fever, EMCAR, meat is also destroyed.

Animals suffering from brucellosis, tuberculosis, etc. are slaughtered at the slaughterhouse in compliance with certain rules.

The meat of animals infected with anthrax, botulism, tularemia, infectious enterotoxemia, INAN, rinderpest, camel distemper, epizootic lymphangitis, rabies, malignant edema and glanders is not allowed to be eaten. The carcass with the skin is burned, and the place where the carcass was located is thoroughly disinfected. All objects, clothing, etc., that come into contact with such a carcass, are disinfected.

MEAT PRESERVATION

Purposes to kill microorganisms or slow down their development. Canned meat by physical and chemical means.

Physical - cooling, freezing, heat treatment.

Chemical - salting, smoking, pickling.

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/

Ministry of Education and Science of the Russian Federation

FEDERAL STATE BUDGET

EDUCATIONAL INSTITUTION

HIGHER PROFESSIONAL EDUCATION

"ORENBURG STATE UNIVERSITY"

Faculty of Chemistry and Biology

Department of Microbiology

COURSE WORK

in the discipline "Sanitary and food microbiology"

Microbiology of meat and meat products

OGU 020209.65.5014.048 OO

Work manager

cand. biol. Sci., Associate Professor, Department of Microbiology

E.A. Drozdova

Executor

student of group 10 MB A.R. Khamidullin

Orenburg 2014

annotation

In this term paper the question of the microbiology of meat and meat products is considered: its contamination with microorganisms, the composition of the microflora meat products, storage and deterioration.

The first section includes a description of the ways in which meat is contaminated with microorganisms.

In the second section - the microflora of fresh meat and semi-finished products.

The third section is devoted to food poisoning and toxicosis.

The fourth section considers the factors influencing the development of microorganisms during the maturation of meat.

The fifth section describes meat defects caused by microorganisms.

The sixth section is devoted to the storage of meat.

The seventh section includes the microbiology of poultry meat.

And, finally, the eighth section is devoted to the microbiology of sausages.

The work was printed on 24 pages using 8 sources.

This term paper discusses the microbiology of meat and meat products: its colonization by microorganisms, the composition of the microflora of meat products, storage and spoilage.

The content of the course work is as follows.

The first section includes a description of the ways of meat contamination by microorganisms.

The second section - the microflora of fresh meat and convenience foods.

The third section is devoted to foodborne diseases and toxemia.

The fourth section examines the factors influencing the growth of microorganisms during the maturation of the meat.

The fifth section describes the evils of meat caused by microorganisms.

The sixth section is devoted to the storage of meat.

The seventh section includes microbiology of poultry meat.

Finally, the eighth section dedicated microbiology sausages.

Work done by printing 24 pages with 8 sources.

Introduction

6. Meat storage

6.1 Cooling

6.2 Freezing

7. Microbiology of poultry meat

Conclusion

microorganism meat contamination semi-finished product

Introduction

Meat, meat products and poultry products are of great importance in human nutrition, providing the body's needs for protein of high biological value. The meat is very delicate product, rapidly changing its qualitative characteristics under the influence of microorganisms. In this regard, an important task is to obtain meat with a low content of microorganisms.

In the presence of microbes on the surface or inside the meat, it is necessary to limit their reproduction and enzymatic activity, as well as to reduce their number. These tasks are solved different methods canning using high and low temperatures, salting, smoking, drying, etc. Currently, combined methods of meat preservation are used, which makes it possible to achieve the maximum reduction in the number of microorganisms while maintaining the quality of meat products.

The initial microflora of meat consists of various microorganisms that break down proteins, fats and carbohydrates. A certain level of decomposition of the organic components of meat and, especially, the glycolytic activity of microbes is useful in the manufacture of meat products. The content of beneficial microorganisms in meat is low, and it is the higher, the more hygienic the meat is obtained. The bulk of the microflora are harmful microorganisms that significantly reduce the quality of meat products.

Along with the saprophytic microflora, pathogenic and toxigenic microorganisms enter the meat, causing infectious diseases and food poisoning. Therefore, meat and meat products are subject to strict hygienic control by the veterinary service and sanitary and epidemiological surveillance authorities.

1. Ways of contamination of meat by microorganisms

The meat of healthy animals is usually sterile. But it is a good nutrient substrate for many organisms, and therefore, it is easily spoiled.

There are the following ways of contamination of meat:

1. endogenous (lifetime) seeding - occurs when the physiological state of the animal's body is disturbed. The muscles of animals that have undergone starvation before slaughter, severe overwork, hypothermia of the body are easily seeded with microorganisms as a result of a weakening of natural resistance. Intravital seeding of meat occurs in animals suffering from infectious diseases, the organs and tissues of which contain pathogens;

2. exogenous seeding - can occur when primary processing and carcass cutting. Sources of contamination are the skin of animals, the contents gastrointestinal tract, equipment, air, vehicles, tools, hands, clothes and shoes of workers in contact with meat. Therefore, the microflora of meat is diverse in number and composition.

Subject to sanitary and hygienic production rules, there are no more than a few thousand or tens of thousands of bacterial cells per 1 cm2 of fresh meat carcass surface area. With a low level of sanitary condition in the slaughter and dressing shops, the number of microorganisms per 1 cm2 of carcass surface area can reach hundreds of thousands or even millions.

2. Microflora of fresh meat and semi-finished products

The qualitative composition of the microflora of fresh meat is diverse. No matter how carefully the meat is processed during slaughter, microorganisms still remain on the surface of the carcass. Among them, E. coli (Escherichia coli), Proteus vulgaris, spore-forming rods (Bacillus subtilis, B. mesentericus, Clostridium sporogenes, Cl. putrificum, etc.) are found. Often fungal spores get on the surface of the meat.

Meat offal (brains, kidneys, heart, etc.), due to the relatively high content of blood and moisture in them, is usually more contaminated with microbes than meat, and therefore undergoes rapid spoilage.

Meat semi-finished products, especially small pieces and minced meat, contain more microorganisms than the meat from which they are made and therefore deteriorate faster. Meat semi-finished products are infected during the manufacturing process from the outside (from equipment, inventory, from the air). Among these microorganisms, there are many possible pathogens of meat spoilage that can actively affect the proteins, fat and other substances of meat that make up its composition. Poorly bled meat is more likely to spoil.

Microbes penetrate deep into the tissues along the fascia, bones, and blood vessels. The penetration of bacteria into the thickness of the meat indicates a decrease in its quality. This is the basis for bacterioscopic examination of meat, which allows you to quickly determine the degree of its freshness.

For research, pieces of meat are sterilely cut out at different depths and the cut sides are applied to a glass slide to get prints. The smears obtained are Gram-stained and microscopically examined. At the same time, the number of bacteria and the degree of breakdown of muscle tissue are determined.

3. Food poisoning and toxicosis transmitted through meat

Meat can also be infected with toxigenic bacteria.

Toxic infections are caused by salmonella (Salmonella typhimurium, S. dublin, S. cholerasuis), bacteria from the group of opportunistic microflora: E. coli, Proteus vulgaris, cocci and other microorganisms.

Toxicosis is caused only by toxins (staphylococci, streptococci, etc.).

The penetration of Salmonella into the muscles is possible during the life of the animal. Toxic infections occur when eating poorly cooked meat. The causative agents of toxic infections can get on meat from water, from equipment, tools, in violation of sanitary rules. Often the carriers of salmonella are rodents (rats, mice), flies, wild birds, from farm animals - cattle and pigs. Meat infected with salmonella, outwardly, has almost no changes, does not raise suspicions of its unsuitability.

Opportunistic pathogens, among which the most common Escherichia (E. coli), long time stored in meat products and can cause food poisoning. Common pathogens are bacteria of the genus Proteus, the main representative of which is Proteus vulgaris, which has proteolytic properties. Well-cooked meat, even infected with Proteus, does not cause poisoning.

Botulism is a severe toxic infection that occurs after eating meat containing C. botulinum and its toxins. The causative agent and its toxin in the products are distributed unevenly (locally). Meat from animals with botulism should not be used for food. With botulism, the mortality rate reaches 70-80%.

Toxicosis can be of staphylococcal and streptococcal origin. Certain strains of golden (Staphilococcus aureus) and white staphylococci are able to produce a thermostable enterotoxin that can withstand boiling for 30 minutes. The appearance of meat products containing enterotoxin does not change.

Animal meat can be infected with anthrax, tularemia, typhoid fever, leptospirosis, glanders, tuberculosis, brucellosis. For humans, brucellosis of sheep and goats is of particular danger.

4. Factors affecting the development of microorganisms during meat maturation

The reproduction of microbes in meat depends on the temperature external environment, humidity, osmotic pressure, pH value of meat and other factors.

Temperature is an important factor contributing to the growth of bacteria. For example, in a piece of meat weighing 2 kg at a temperature of 18-20 ° C during the day, microbes penetrate to a depth of 2-3 cm, at a temperature of 37 ° C during the same time they can be found in the entire thickness of the product. The lower the temperature, the lower the rate of microbial reproduction. But among the microbes there may be psychrophiles that develop at low temperatures. At zero temperature, molds and yeasts develop.

Humidity and osmotic pressure are also of great importance for the development of microorganisms. Reduced humidity delays their development, microbes go into a state of suspended animation, and spores go into the spore stage. Great content moisture leads to an increase in osmotic pressure and concentration of water-soluble substances, which causes plasmolysis of microbial cells. But not all microbes are equally sensitive to osmotic pressure. Molds and yeasts can withstand very high pressure.

The pH value of meat depends on the amount of glycogen and the lactic acid formed from it. After the slaughter of the animal, the reaction of the meat environment is slightly alkaline (pH 7.1-7.2). During the ripening period of the product, under the influence of enzymes, complex biochemical and physico-chemical processes occur. Glycogen is broken down in muscle tissue, lactic acid accumulates, as a result of which the meat becomes acidic (pH 5.5-5.8). After a day, the pH of the meat decreases, in such an environment the growth of putrefactive microbes stops. Along with an increase in acidity, other changes occur: protein denaturation, loosening of muscle tissue, the formation of substances that determine the taste and aroma of ripe meat. Then the process reverses - the amount of acid decreases and by the end of the fourth day the reaction of the medium in the meat becomes alkaline again.

5. Meat defects caused by microorganisms

It has been established that signs of spoilage of meat appear when bacteria accumulate in it in the amount of 107-108 per 1 g or 1 cm2 of its surface. The time to reach this "threshold" concentration of microorganisms depends mainly on the storage temperature and the initial number of microorganisms on the product.

Various undesirable processes can occur in meat, leading to the loss of its freshness, nutritional and culinary properties. Damage to meat manifests itself in the form of: mucus, rotting, acid fermentation, pigmentation, mold.

Mucus occurs during the initial period of storage. It is observed when storage conditions are violated, especially when temperature and air humidity fluctuate (over 90%) in storage areas. Mucus-forming bacteria resistant to low temperatures develop well even at 0°C. Most often, mucus processes occur throughout the carcass or at the site of blood contamination, in the folds. The surface of the meat becomes sticky, gray-white in color, sometimes with an unpleasant sour musty smell. The number of bacteria in it reaches tens, hundreds of millions and even billions per 1 cm3. Mucus-forming microorganisms do not penetrate into the deep layers of meat, so the defect covers only the surface layer. However, such meat cannot be stored, it must be washed with water or a 15-20% salt solution, followed by drying and airing. Places where mucus or smell is especially pronounced are cleaned. Meat should be quickly used for cooking first courses or sent for processing to meat products, which include exposure to high temperatures in the process of their manufacture. This defect is caused mainly by bacteria of the genus Pseudomonas and Achromobacter. When meat is stored at a temperature above 5 ° C, micrococci, streptococci and other microorganisms multiply. When storing meat with signs of mucus, it further deteriorates, called rotting.

Meat decay is a complex process of protein breakdown. Decay is accompanied by the formation and accumulation of various intermediate and final decay products, among which are poisonous, foul-smelling, and volatile. Rotting is accompanied by a change in the structure of tissues and physico-chemical parameters. Rotting is caused by the vital activity of various putrefactive microorganisms. If hygiene rules are not observed, the greatest microbiological contamination of meat is noted. Meat is a good environment for putrefactive microbes, the development of which occurs under certain conditions. Decay can occur under both aerobic and anaerobic conditions. From aerobic bacteria, E. coli, Proteus vulgaris, B. subtilis, B. mesentericus, cocci, etc. take part in the breakdown of proteins. During aerobic decay, under the influence of proteolytic enzymes of putrefactive bacteria, meat proteins are decomposed with the formation of end products - carbon dioxide, hydrogen sulfide, ammonia, salts of phosphoric acid, water. First, aerobes develop on the surface of the meat, and then penetrate into deep-lying tissues. There are several phases of the putrefactive process. Coccal forms are replaced by non-spore-forming rods, which then give way to spore rods (bacilli). The surface of the meat gradually softens, becomes smeared, acquires a brown or grayish-green color, appears bad smell. Anaerobic decay begins in the depths of the muscle tissue, which is caused by anaerobic and facultative anaerobic bacteria that have entered the meat endogenously from the gastrointestinal tract of the animal. They secrete proteolytic and saccharolytic enzymes, resulting in the breakdown of not only proteins, but also carbohydrates and fats. During anaerobic decay of meat, the same changes in the organoleptic properties of meat (color, texture, smell) are observed, as in aerobic decay, but they are accompanied by an even more unpleasant, fetid odor. Of the anaerobic bacteria, meat is decomposed mainly by clostridia: Cl. perfringens, Cl. putrificum, Cl. sporogenes, etc. Under normal conditions, during meat decay, anaerobic and aerobic processes most often occur simultaneously.

Acid fermentation (souring of meat) - more often observed in those meat products that are rich in glycogen (liver). It often occurs due to poor bleeding of animals during slaughter, as well as in cases where the carcasses are not cooled for a long time. The process is caused by lactic acid bacilli of the genus Lactobacterium, anaerobic bacteria Clostridium putrifaciens, sometimes yeast. Reproducing in meat, these microorganisms decompose carbohydrates in muscle tissue with the release of organic acids. The meat acquires an unpleasant sour smell, a pale gray or greenish-gray color on the cut and a soft texture. The resulting fermentation products retard the development of putrefactive bacteria, but create favorable conditions for mold fungi.

Molding of meat is caused by the growth of various molds on the surface of the meat. Their development usually begins with the appearance of an easily erasable cobweb coating of white color. In the future, more or less powerful raids are formed. different color. Molds in the form of spores fall on the surface of the meat from the environment. Mold can develop if there is acid environment, at relatively low air humidity (75%), sub-zero temperatures, poor air ventilation and long-term storage of meat. Molds decompose fats and proteins with the help of enzymes, increase the pH of the environment, release volatile substances, meat acquires musty smell. Molding of meat is caused by fungi from the genus Mucor, Rhizopus, Thamnidium. They cause the formation of white or gray fluffy plaques. Black plaque gives Cladosporium, green - fungi of the genus Penicillium, yellowish - Aspergillus. In addition, some molds found on meat are capable of producing toxic substances (Aspergillus flavus, Penicillium puberulum).

Pigmentation of meat is the appearance of colored spots, a consequence of the development of pigment-forming bacteria on its surface. Thus, the development of the "wonderful stick" (Serratia marcescens) or yeast of the genus Rhodotorula leads to the formation of red spots that are not characteristic of meat, the development of Sarcina flava - yellow spots, Pseudomonas aeruginosa - blue, Pseudomonas fluorescens - green, etc. Most of these bacteria do not cause deep changes in the meat and do not form toxic substances. After examination and removal of pigmented colonies, the meat can be used.

Glow occurs as a result of reproduction on the surface of the meat of luminous bacteria that have the ability to glow - phosphorescence. The glow is due to the presence in the cells of these bacteria of a photogenic substance - luciferin, which is oxidized by atmospheric oxygen. The group of photobacteria includes various non-spore gram-negative and gram-positive rods, cocci, vibrios. A typical representative is Photobacterium phosphoreum - an immobile coccus-like bacillus. Photogenic bacteria develop well on fish and meat, but do not cause any changes in smell, texture and other organoleptic characteristics.

6. Meat storage

Meat - perishable product. To save it, use different ways canning.

The most common way to preserve meat is by exposure to low temperatures: refrigeration and freezing. Low temperature delays the development of microbiological, enzymatic processes and almost does not change the properties of the product.

6.1 Cooling

The microflora of meat stored in the cooling chambers is diverse in composition. By the end of cooling in the deep layers of meat, the temperature reaches 0-4? Consequently, it is mainly psychrophilic microorganisms that survive. But some pathogenic bacteria (salmonella, toxigenic staphylococci) remain viable for a long time at low temperatures. On chilled meat under anaerobic conditions, non-spore-forming gram-negative bacteria of the genus Pseudomonas and Achromobacter multiply, as well as fungi and yeast. To extend the shelf life of chilled meat, it is possible, in addition to cold, to use additional means of influencing microorganisms:

1. increased content in the atmosphere carbon dioxide(up to 10-15%);

2. in an atmosphere of nitrogen (90-99%), mucilage of meat occurs 2-3 times slower than when stored in air;

3. ultraviolet irradiation;

4. radurization (treatment with gamma rays), the contamination is reduced hundreds and thousands of times, radioresistant microorganisms are preserved. Storage periods increase several times;

5. periodic ozonation (ozone content up to 10 mg/m3) of storage chambers;

6. surface treatment of meat with a mixture of organic acids (citric, sorbic, propionic, acetic, etc.) and their salts;

7. treatment with a composition of essential oils various spices;

8. treatment of the surface of the meat with the antibiotic substance pamalin.

The effectiveness of the use of additional means of influencing the microflora largely depends on the degree of contamination of it with microorganisms. If the meat was inoculated in large quantities with multiplying microorganisms, then even under storage conditions that retard their growth, it undergoes spoilage under the action of enzymes secreted by microbes.

Techniques for storing meat and meat products under anaerobic conditions are being developed:

1. vacuum packed;

2. Packed with gas-tight film.

With an increase in the shelf life of such products, the meat is spoiled due to the development of some facultative anaerobic psychrophilic microorganisms.

Microbiological indicators of chilled meat:

1. QMAFANM no more than 1,103 (semi-finished products - 5,105);

2. BGKP are not allowed in 0.1 g (semi-finished products - in 0.001 g);

3. pathogenic bacteria must be absent in 25 g of the product.

6.2 Freezing

During the freezing of meat, a significant number of microorganisms contained in the chilled meat die off. The degree of survival of microbes depends on the method of freezing. So, when meat is frozen in liquid nitrogen (-196? C), more bacteria die than during conventional freezing in air (at t from -18 to 30? C).

During the storage of frozen meat, the microorganisms remaining in it gradually die off. At the same time, the more microbes there were on the meat before freezing, the higher its contamination after freezing.

The microflora of frozen meat is dominated by micrococci. BGKP, Proteus are found, and pathogenic bacteria, such as Salmonella, Listeria, Yersinia, can also survive. So, during long-term storage of frozen meat at t - 18? C, Yersinia survived for 75 days.

Meat should be thawed immediately before use, since the surviving cells do not lose their activity and growth rate. During defrosting, additional contamination of the meat with microbes from the outside should not be allowed.

6.3 Drying, drying, canning, smoking, salting

Drying is one of the oldest methods of preserving meat. Moisture content of dried meat different ways, below the limit allowing the development of microbes. However, there is always a certain amount of microbes on it, these are mainly micrococci, bacterial spores and molds. With an increase in the moisture content of the meat, they begin to multiply.

In addition to drying, drying is used, during which up to 35% of moisture is removed. During storage, dry and dried meat should be protected from contamination by microorganisms and strictly observe the temperature and humidity conditions.

Preservation of meat by high temperature (canned food) is widely used. Meat intended for long-term storage is subjected to sterilization at t above 100? C (115-120? C). Most resistant to high temperature spores of B. subtilis, B. mesentericus, Cl. botulinum. If spores of bacilli remain in canned food, then some of them can germinate and cause swelling (bombing) of cans.

Smoked meat is also carried out in order to preserve the product. In addition to the loss of water, meat during smoking is exposed to the products of dry distillation of wood, which leads to the death of microorganisms. Gram-negative bacteria are more sensitive to smoke, less - staphylococci, mold fungi, spores. In the process of smoking, meat products acquire a specific taste and aroma.

Meat salting is based on the property of NaCl to increase osmotic pressure, create plasmolysis and thereby inhibit (slow down) microbiological processes. Food spoilage can be caused by gallophiles, bacteria that can withstand high salt concentrations. Also in the brine may be micrococci, enterococci, lactic streptococci, bacilli, less often clostridia and fungi.

7. Microbiology of poultry meat

The microflora of the poultry carcass depends on the production conditions and the method of cooling. Semi-gutted poultry carcasses are usually more contaminated with microorganisms than gutted ones. When half-gutted, intestinal rupture often occurs, which leads to infection of the carcass with intestinal microorganisms. Damage to the skin during feathering also contributes to microbial infection of the muscles.

The microflora of the poultry carcass consists mainly of aerobic non-spore rod-shaped bacteria of the genera Pseudomonas (up to 70-75%), Acinetobacter, Moraxella. There are facultative anaerobic bacteria: Aeromonas, Enterobacter, Escherichia coli, Proteus. Salmonella is often found in poultry meat.

To lengthen the shelf life, the carcasses are cooled:

1. placed in gas-tight films;

2. into the atmosphere with high content CO2 (t -2, -3? С);

3. treated with sorbic acid and its salts;

4. irradiated with gamma rays;

5. freeze.

Frozen poultry is stored without microbial spoilage at t not higher than -15? C for months. Frozen chickens can develop yeast and mold, Pseudomonas. The first sign of spoilage is a foreign smell. The types of spoilage are the same as those of animal meat. The degree of freshness of poultry meat is determined by bacterioscopy of imprint smears and freshness is determined by the same indicators.

The quality of chilled poultry meat is evaluated by:

1. QMAFANM (CFU (colony forming unit), no more than 1,104 in 1 g);

2. the absence of pathogenic bacteria, including salmonella and listeria in 25 g of the product.

8. Microbiology of sausages

Sausages are meat products prepared from minced meat with or without a casing, subjected to heat treatment or fermentation until ready to eat. The minced meat (depending on the recipe) includes: meat, bacon, skimmed milk, egg products, spices, seasonings, as binders - flour, starch, etc.

The range of sausage products includes more than 200 items. Sausages are classified according to the type of product and the method of processing into boiled, semi-smoked, smoked, stuffed, sausages and sausages, liver, blood, meat loaves, pates, brawns and jellies. Usually these products are eaten without additional heat treatment. Therefore, increased sanitary requirements are imposed on these products and the technological process of their manufacture.

8.1 Sources of contamination of sausages

In the process of preparing sausages, minced meat is inoculated with microorganisms that enter it from various sources at all stages. technological process its preparation: from raw materials, when preparing meat, curing, making minced meat, filling the casing with minced sausage.

The main source of contamination is raw materials. Raw materials must be obtained from healthy animals. Raw materials with various signs of deterioration, as well as with a contaminated surface, contain a large number of microorganisms. Such raw materials can be allowed into production only after a thorough sanitary check. The contamination increases sharply when preparing meat for minced meat. Microorganisms get from the hands of workers, from overalls, from tools, tables, inventory, containers, from the air of industrial premises. Among these microorganisms may be putrefactive. To reduce contamination, it is necessary to speed up the process of cutting meat and carry it out at a low temperature of industrial premises. It is necessary to strictly observe sanitary and hygienic standards.

When salting, the source of contamination by organisms can be salt containing salt-tolerant and salt-loving microorganisms: bacilli, yeast, mold spores, cocci.

In the process of making minced meat, contamination occurs during mechanical operations (chopping meat and processing minced meat in a mixing machine) from equipment, workers' hands, inventory, containers, from indoor air. Practice shows that when chopping meat, its contamination increases by an average of 10 times.

Additional seeding of minced meat is possible by adding bacon and spices. With spices, especially with pepper, a lot of spore-forming bacteria get into the minced meat. Therefore, it is necessary to use sterilized spices. When stuffing sausage sticks, further seeding of minced meat with microorganisms from syringes is possible.

Another source of contamination during this operation is the sausage casing. Apply natural and artificial shells. Artificial casings are more hygienic. Manual stuffing of minced meat into the casing in the manufacture of sausages (puff, tongue) leads to significant microbial contamination. In the study of such sausages, E. coli was isolated in 35.5% of cases, in 20% - Proteus vulgaris.

8.2 Changes in the microflora of minced meat in the manufacture of sausages

The microflora of raw sausage meat usually contains 105-107 bacteria per 1 g, the vast majority of them are gram-negative nonsporing rods. In much smaller quantities, micrococci, spore bacteria, BGKP, and Proteus are found.

After stuffing the shells with minced meat, boiled and semi-smoked sausages are subjected to sedimentation, frying, boiling and cooling. Half-smoked sausages are additionally smoked and dried.

Draft is carried out at a temperature of 2? C and a relative humidity of 85-95% for 2-4 hours. At this stage, the quantitative and qualitative composition of the microflora almost does not change.

Roasting is carried out with hot smoke at a temperature of 80-110? C for 0.5-2 hours. Under the action of antiseptic substances of smoke and temperature, the number of microorganisms on the surface of the loaf is reduced. However, in the depth of the loaf the temperature does not exceed 40-45?C, so the number of bacteria decreases slightly.

Boiling leads to a rise in temperature inside the loaf up to 75 ° C, while up to 90% or more of all microorganisms die. All vegetative cells die. Usually spore-forming rods and the most resistant micrococci persist, and toxin-forming bacteria may also persist.

The more residual microflora, the more it was contained in minced meat before heat treatment. More bacteria survive in high-fat sausages, as the fat creates a protective zone around their cells.

After cooking, sausages are quickly cooled to avoid the reproduction of residual microflora in them.

Smoking and drying are used in the manufacture of semi-smoked sausages. During smoking, the number of bacteria in them decreases. During storage of sausages, secondary infection of the surface and a gradual increase in the number of bacteria occur.

The number of microflora increases the faster, the higher the storage temperature and relative humidity. Shell-free types of sausage products (meat bread, carbonate) after heat treatment have an insignificant total contamination and should not contain pathogenic and conditionally pathogenic microorganisms. However, since these products do not have a protective shell, if sanitary standards are violated, they can become contaminated with microorganisms. The most common on these products are E. coli, Proteus vulgaris, spore putrefactive bacteria, and cocci.

Smoked sausages are divided into raw smoked and boiled-smoked. Raw-smoked sausages are subjected to long-term draft (5-7 days), cold smoking at a temperature of 18-25? C and drying up to 1.5 months (humidity 25-35%). The composition of the microflora of these sausages is very diverse: gram-negative bacteria, E. coli, Proteus vulgaris, spore aerobic bacilli (B. subtilis, B. mesentericus), anaerobic clostridia, staphylococci, yeast, lactic acid bacilli.

During the ripening of sausages, the composition of the microflora changes. As a result of the release of antibiotic substances by lactic acid bacteria, many bacteria of the original minced flora are displaced.

By the end of the ripening of sausages, the basis of the microflora is lactic acid bacteria and micrococci.

Boiled-smoked sausages are subjected to less prolonged draft (1-2 days), hot smoking at a temperature of 50-60? C, cooking, secondary smoking at a temperature of 32-45? C and shorter drying (7-15 days). The composition of the microflora at the end of drying is almost the same as the microflora raw smoked sausages.

To improve the quality of smoked sausages, specially selected strains of lactic acid bacteria (Lactobacterium plantarum, L. acidophilum) and denitrifying micrococci are used. They produce dry bacterial preparations "ACID-SK" from acidophilic lactic acid bacteria and "BK-SK" containing a mixture of lactic acid bacilli and micrococci. The bacteria of these preparations have a high acid-forming ability, they produce a large amount of organic acids and other substances that give the product a specific taste and aroma. The preparations have, in addition, antibiotic activity against BGKP, Proteus.

Currently, the possibility of creating preparations containing bifidobacteria in combination with lactic acid bacteria is being considered.

Abroad, raw smoked sausages are produced using molds that are applied to the surface of the loaf. Developing mold covers the loaf of sausage with a thin layer, thereby protecting it from excessive drying, exposure to light and atmospheric oxygen, as well as preventing the development of harmful bacteria and yeast. Metabolic products and mold enzymes penetrate into minced meat and give the sausages a specific taste and aroma.

Subject to the sausage production sanitary and hygienic requirements and the use of high-quality raw materials, the bacterial contamination of freshly prepared finished products is: for boiled sausages - 103 in 1 g, semi-smoked - 102, liver - 104-105.

The microflora consists mainly of spore-bearing bacteria and coccal forms. Permissible degree contamination of sausages with bacteria is normalized.

Boiled sausages, liver sausages, sausages, brawns are especially perishable products. Liver sausages and brawns contain significantly more microorganisms than other sausages. They have a relatively high humidity and are prepared from raw materials that are usually highly contaminated with microorganisms. Although heat treatment and destroys many of them, but still a sufficient number remains.

The temperature, shelf life and sale of these products in the distribution network and at public catering establishments are strictly limited. If these requirements are violated, the products are subject to spoilage.

Relatively more stable in storage are semi-smoked and especially smoked sausages, which are distinguished by a low water content, an increased amount of salt and, in addition, treatment with antiseptic substances during smoking.

Types of spoilage of sausages are basically similar to spoilage of meat. Most often it is: souring, mucus, rotting, molding, rancidity, pigmentation.

Souring of sausages is caused by fermenting carbohydrates (introduced into minced meat in the form of flour and other herbal supplements), lactic acid bacteria, and Clostridium perfringens. This type of spoilage is more common in boiled and liver sausages which contain a lot of carbohydrates and have high moisture content. When carbohydrates decompose, organic acids accumulate, which give sausages sour taste and smell. The consistency and color of minced meat do not change. In the future, with the access of oxygen, a grayish-green color of minced meat may appear.

The mucus of the membranes is usually due to the growth of non-spore-bearing rod-shaped bacteria and micrococci.

The rotting of sausages is caused by the vital activity of putrefactive bacteria: Pr. vulgaris, B. subtilis, B. mesentericum, Cl. sporogenes, etc. The putrefactive decomposition of sausages occurs simultaneously throughout the entire thickness of the loaf. Rotting is accompanied by the release of foul-smelling decomposition products - proteins, fats and carbohydrates; sausage acquires a loose texture.

Molding of sausages appears during storage at high humidity. Molds develop on the casing of sausages, forming dry or wet plaques. With loose stuffing, mold fungi can penetrate into the loaf. Mushrooms are resistant to smoke substances and are able to multiply at elevated osmotic pressure. Molding is the most common type of spoilage of semi-smoked and smoked sausages. To prevent mold, it is recommended to treat the loaves with potassium sorbate and volatile preparations.

Rancidity most often occurs during long-term storage of smoked sausages. It is caused by the decomposition of fat by microbes. The oxidation of fat hydrolysis products is accompanied by the formation of aldehydes and ketones. Sausages acquire a rancid taste, an unpleasant odor, and the fat turns yellow. The causative agents are most often bacteria of the genus Pseudomonas and others.

Pigmentation - the appearance on the shells of boiled and half-smoked sausages raids of various colors due to the development of pigment bacteria. Coccal forms of bacteria and yeast sometimes develop on the casings of smoked sausages, forming a gray-brown dry coating in the form of frost. A white coating on the surface of a loaf of raw smoked sausages may be the result of salt crystallization on the casing.

To increase the shelf life of sausages, in addition to low temperatures, it is recommended:

1. ozonation of lockers;

2. storage and transportation of sausages in an atmosphere of gaseous nitrogen.

Other ways to prevent microbial spoilage have been proposed, such as:

1. use of chitosan as a preservative;

2. mixtures of protamine with glycine, sodium acetate and lysozyme;

3. the use of food additive "Amfibakon", which has a bactericidal effect and reduces the number of microorganisms;

4. use of polyamide casings and vacuum bags.

A new direction is being developed - the formation of environmentally friendly protective polymer shells based on latexes directly on the surface of products. With the help of latex coatings, products are protected from unwanted microflora during transportation and sale.

Conclusion

Meat and meat products are the most important food products, as they contain almost all the nutrients necessary for the human body. The main raw materials for the production of meat and meat products are: cattle, pigs, sheep, Domestic bird. The meat of horses, deer, buffaloes, rabbits, meat of wild animals and poultry is also used.

The microflora of meat is random and heterogeneous in composition. It may include various bacteria, mold spores, etc. Under favorable conditions, bacteria multiply rapidly and gradually penetrate into the thickness of the meat, causing it to spoil.

List of sources used

1. Askalonov S.P. Microbiological research and sanitary examination food products/ S.P. Ascalonov. - Kyiv: Medizdat. - 1955. - 238 p.

2. Verbina N.M. Microbiology food production/ N.M. Verbina. - M.: Agropromizdat. - 1988. - 357 p.

3. Zharikova G.G. Microbiology food products. Sanitation and hygiene: a textbook for universities / G.G. Zharikov. - M.: Publishing Center "Academy". - 2008. - 304 p.

4. Luzina N.I. Microbiology of meat and meat products / N.I. Luzin. - Kemerovo. - 2004. - 75 p.

5. Mudretsova-Wiss K.A. Microbiology, sanitation and hygiene / K.A. Mudretsova-Viss. - M.: ID "FORUM": INFRA-M. - 2009. - 400 p.

6. Sidorov M.A. Microbiology of meat and meat products / M.A. Sidorov. - M.: Kolos. - 1996. - 395 p.

7. Shevchenko V.V. Merchandising and expertise consumer goods/ V.V. Shevchenko. - M.: INFRA-M. - 2009. - 752 p.

8. Microbiology of meat [Electronic resource]. - Access mode: http://biobib.ru. 11/19/14.

Hosted on Allbest.ru

...

Similar Documents

The main nutrients of meat and meat products. Proteins, lipids and carbohydrates of muscle tissue, minerals and vitamins. The structure of the main tissues of meat. Medium daily requirement adult human in amino acids. The composition of bone and adipose tissue.

presentation, added 11/06/2014


Consideration of the spread of diseases caused by opportunistic pathogens. Characterization of staphylococci as ubiquitous bacteria. The study of clinical manifestations of staphylococcal infections in newborns and adults.

test, added 04/10/2014


Characterization of pathogenic microorganisms. Infection, ways and sources of its transmission. Diseases transmitted to humans through meat products. Immunity and its types. Decomposition of proteins by microorganisms. Damage to bakery products.

test, added 01/13/2011


Poultry farming as an industry Agriculture, features of the production of poultry meat and food eggs in industrial scale. Classification of breeds of chickens by egg production and live weight, selection work to improve productive and breeding qualities.

abstract, added 01/30/2015


Description and habitats of a sea cow or cabbage - a marine mammal of the siren order (sea maidens). Description of appearance, herbivorous diet of her diet. The reasons for the extermination of the animal because of its subcutaneous fat and delicious tender meat.

presentation, added 05/08/2015


Microbiological standards of drinking water and methods of its purification. Characteristics of intestinal bacteriophages, their significance as sanitary indicative microorganisms. Major foodborne infections. Effect of drying and freezing fish products on microorganisms.

test, added 08/06/2015


Characterization of the main indicators of the microflora of soil, water, air, the human body and plant materials. The role of microorganisms in the cycle of substances in nature. Influence of environmental factors on microorganisms. Goals and objectives of sanitary microbiology.

abstract, added 06/12/2011


Basic elements and chemical composition muscle tissue. Types of proteins of sarcoplasm and myofibrils, their content to the total number of proteins, molecular weight, distribution in the structural elements of the muscle. Their functions and role in the body. The structure of the myosin molecule.

presentation, added 12/14/2014


Brief historical background and classification of microorganisms that cause food toxicosis. Cultural properties of this class of microorganisms. Sources of product contamination with staphylococci, diagnosis and treatment of diseases caused by them.

term paper, added 12/18/2010


The study of the subject, the main tasks and the history of the development of medical microbiology. Systematics and classification of microorganisms. Fundamentals of bacterial morphology. Study of the structural features of a bacterial cell. The importance of microorganisms in human life.

Vyatka State Agricultural Academy

Department of Microbiology, Virology and Pharmacology

Personal file No. VTZ-09020

Registration No.____

Grade_______________

TEST

By discipline : Microbiology of food products. Sanitation and hygiene»

On the topic : "Microbiology of animal meat"

Lecturer Smirnova L.I.

Made by Kokoulina S.N.

3rd year student

Faculty of Veterinary Medicine

Correspondence form of education

Specialty "080401 Commodity research and examination of goods (in the field of production and circulation of agricultural raw materials and food products)"

The work entered the dean's office "____" ____________________ 2011

Kirov, 2011

1.Characteristics of the microflora of meat, sources of contamination…………………3

2. Changes in microflora during meat storage…………………………..5

3. Product defects of microbial origin or infectious diseases and prevention methods………………………………………………………………………………………. ....................12

4. Conditions and terms of storage of meat in the distribution network…………………………….17

5. Preservation methods………………………………………………………………………………………………. ...19

6.Microbiological safety indicators……………………………..26

7. GOST, TU, research methods……………………………..............................27

1. Characteristics of the microflora of meat, sources of seeding.

Meat - a carcass or part of a carcass obtained from the slaughter of livestock, which is a combination of muscle, connective, adipose and bone (or without it) tissues. Slaughter animals include cattle, pigs, small cattle, horses, buffaloes, camels, reindeer, yaks. The meat of other domestic and wild animals is also sold: rabbits, nutrias, wild boars, wild ungulates, bears, wild reindeer, hares, etc.

Microorganisms, as a rule, are not found in the blood, muscles and internal organs of healthy animals. This is confirmed by the results of microbiological studies of slaughter products of healthy and rested animals, killed and opened in compliance with the rules of sterility. If these rules are not observed, then during the slaughter of animals, meat and internal organs are obtained containing various amounts of saprophytic microorganisms, including putrefactive bacteria, CGB, spores of moldy fungi, yeast, streptomycetes, cocci, and in some cases salmonella and other pathogenic microorganisms. There are two ways of contamination of organs and tissues of animals with microorganisms: endogenous and exogenous.

Endogenous contamination with microorganisms can occur both during the life of the animal and after slaughter.

Intravital seeding of meat occurs in animals with infectious diseases, the organs and tissues of which contain the causative agent of the disease.

Most often, endogenous seeding of animal tissues occurs during fatigue that occurs in the process of transporting or driving animals to meat processing plants.

The endogenous path of seeding begins immediately after slaughter and exsanguination, i.e. after the death of the animal. At the same time, the intestinal wall becomes easily permeable to microorganisms contained in the gastrointestinal tract, they penetrate into the surrounding tissues, where their number increases several times. If the slaughter of the animal is carried out in such a tired state, then some of the microbes preserved in the meat further cause spoilage of the product. Therefore, animals are allowed to rest for at least 3 days before slaughter. During this time, the glycogen content in the muscles of the animal increases, which after slaughter increases the amount of lactic acid and the resistance of meat to putrefactive microbes.

Exogenous contamination occurs during the slaughter of animals and subsequent carcass cutting operations. The sources of exogenous contamination are the skin of animals, the contents of the gastrointestinal tract, air, equipment, vehicles, hands, clothes and shoes of workers who come into contact with meat, and water used to strip ink.

The qualitative composition of the microflora of fresh meat is diverse. The bulk of this microflora is made up of microorganisms that are permanent inhabitants of the gastrointestinal tract.

The most commonly found are staphylococci and micrococci, BGKP, different kinds putrefactive aerobic bacilli, anaerobic clostridia and non-spore bacteria, yeasts, lactic acid bacilli, spores of streptomycetes and moldy fungi.

2. Changes in microflora during storage.

In refrigerators and meat processing plants, meat and meat products are stored at low temperatures in chilled and frozen form.
In the process of cold storage, depending on the temperature conditions of storage of chilled and frozen meat, unequal changes in the quantitative and group composition of microflora occur, the reproduction of which can cause spoilage of the product.

Changes in the microflora of chilled meat.

The microflora of meat stored in the cooling chambers is diverse in composition and is usually represented by mesophiles, thermophiles and psychrophiles, that is, microorganisms that have unequal temperature growth limits.

By the end of cooling in the deep layers of meat, the temperature should reach 0-4 ° C. Consequently, only those microorganisms that have the lowest temperature limits for growth and reproduction, i.e., psychrophilic, can develop on chilled meat during storage.

Thermophilic and most mesophilic microorganisms, which do not develop at temperatures close to 0 ° C, after cooling the meat, completely suspend their vital activity, passing into anabiosis. During the subsequent storage of the product, these microorganisms gradually die off and, consequently, their number decreases. But some pathogenic and toxigenic bacteria from the mesophyll group (Salmonella, toxigenic staphylococci, etc.) remain viable at low temperatures for a long time and do not die off during storage of chilled meat.

The reproduction of microorganisms in meat at low temperatures goes through several phases (lag phase, logarithmic, maximum stationary and dying phase). In the initial period of storage of chilled meat, psychrophilic microorganisms, being in the lag phase (growth inhibition phase), do not multiply for some time or their reproduction occurs to a small extent. For this reason, the composition of the microflora of meat during this period almost does not change.

The duration of the growth inhibition phase of psychrophilic microorganisms depends on the temperature at which the meat was before entering storage. If the meat comes from chambers with a lower temperature (3-4°C) and it contains psychrophilic microorganisms in a state of active growth, then the lag phase will be shorter.
The duration of the growth retardation phase of psychrophiles is also affected by the cooling rate, temperature and air humidity during meat storage. With sharp and rapid cooling, lower temperature and humidity, the lag phase increases.

The duration of the lag phase is significantly affected by the degree of microorganism contamination of meat carcasses received for storage. The lower the degree of contamination of the meat, the longer will be the delay in the growth of the microorganisms present on it. Subject to the established temperature and humidity conditions (relative humidity 85–90%, air temperature from -1 to +1 ° C) on chilled meat obtained from the slaughter of healthy, rested animals in compliance with all basic sanitary rules and usually having a slight microbial contamination , the reproduction of microorganisms is delayed by 3–5 days or more. With a high degree of contamination of meat with microorganisms, the growth inhibition phase of microorganisms is reduced to one day, and sometimes it is only a few hours.
After the lag phase, psychrophilic microorganisms begin to multiply intensively (logarithmic phase), and their number increases sharply.

Depending on the storage conditions of chilled meat (certain temperatures, gas composition of the atmosphere and air humidity), only some psychrophilic microorganisms multiply most actively, for the development of which these certain storage conditions turned out to be the most favorable. The remaining psychrophiles, due to insufficient humidity and low temperature, the gas composition of the atmosphere, unsuitable for their development, or as a result of the suppression of their growth by other types of psychrophilic microorganisms with antagonistic ability, do not multiply and gradually die off. Psychrophilic microorganisms, capable of actively multiplying, eventually become predominant in the composition of the microflora of products stored under these conditions.

Non-spore-forming gram-negative bacteria of the genus Pseudomonas and Achromobacter, as well as molds and aerobic yeasts, mainly of the genera Rhodotorula and Torulopsis, multiply on chilled meat under aerobic storage conditions. The activity of development of one or another group of these psychrophilic microorganisms depends on the temperature and humidity conditions of meat storage.

Under conditions unfavorable for the development of psychrophilic aerobic bacteria (low humidity and more low temperature storage), there is an active growth of molds and aerobic yeasts, which have lower temperature limits for growth and are less demanding on humidity.

If additional means are used during the storage of chilled meat during refrigeration (partial replacement of air with carbon dioxide, complete replacement of air with nitrogen, vacuum packaging), then conditions are created that are unfavorable for the development aerobic microorganisms(aerobic bacteria, molds, aerobic yeasts). The reproduction of these psychrophilic microorganisms is delayed or completely suppressed.

Microbiology of meat. In the blood, muscles of healthy animals, as a rule, microorganisms are absent. The significant content of microbes in meat and meat products is explained by their contamination during processing. Inside the muscles, in the blood, microbes are found only in sick and weakened animals, whose body is not able to prevent the penetration of microflora through the intestinal walls. In the process of primary processing of livestock, microbes from the coat, from the skin, from the intestines, from the slaughter and processing tools, from the equipment, fall on the surface of the carcass. Through the lymphatic and blood vessels, when carcasses are bled on overhead tracks, microbes can penetrate with air inside.

After primary processing, carcasses can contain from tens to hundreds of thousands of microbes per 1 cm2 of surface.

In the process of transportation and commercial cutting of the carcass, the contamination increases even more. With the accumulation of a large number of microbes on the surface of the meat, they spread along the blood and lymphatic vessels, bones, tendons into the inner layers. The penetration rate is the lower, the lower the storage temperature, the higher the fatness, the carcass, or the larger the surface is covered with fat. For example, at 0 ° C, the development of microbes and. their penetration into the interior is slower than at 5°C; meat from well-fed animals of the same species spoils later than meat from lean ones, beef spoils more slowly than pork.

Especially important is the drying crust - a film that forms on the surface of the meat during storage. Without being disturbed, it delays the penetration of microbes inside.

Even in meat that smells of spoilage, bacteria are found only to a depth of 1 cm. If there are a lot of microbes in the inner layers, which can be found out by microscopically examining an imprint on a glass slide from a sterile cut, then the meat should be considered stale. Most often, spoilage of meat as a product of protein composition occurs in the form of aerobic or anaerobic decay.

In addition to the previously described rotting pathogens, meat can be spoiled by Escherichia coli, the Prodigiosum bacterium, etc. The latter leads to the formation of unusually bright red spots on meat and other products.

Various sardines form yellow spots on the meat, other microbes can give it a blue color (Pseudomonas aeruginosa) or greenish (fluorescence bacterium, etc.).

Some microbes can cause meat to ooze off the surface. This defect occurs on cooled and chilled meat, as well as during storage under conditions of high humidity of the ambient air. Sliming becomes noticeable at a content of 5-10 million cells per 1 cm2 of the surface. Sliming does not affect the deep layers of meat and has little effect on its nutritional value, but significantly worsens the presentation. The meat becomes sticky, its color changes. Such meat is not subject to sale through stores.

In addition to bacteria, all kinds of mold fungi can develop on meat. Being aerobes, they affect only the surface layers. By consuming acidic compounds, they raise the pH of the meat, thus preparing it for the subsequent development of putrefactive bacteria.

Molds are very resistant to low temperatures and can grow on meat even at -8°C. This circumstance is one of the reasons that require the storage of frozen meat at lower temperatures.

Microbiology of minced meat. Usually, the microflora of minced meat is much more abundant than the microflora of a whole piece of meat. This is explained by the fact that during the transformation of meat into minced meat, a uniform distribution of microbes occurs in a large number of those on the surface of the meat, in the entire mass of minced meat. Part of the microflora enters the meat from the meat grinder and other equipment. This, as well as the presence of air in minced meat, the availability of fragmented muscle tissue cells to microbes, leads to their rapid reproduction. Spoilage becomes noticeable at a content of 5-10 million bacterial cells per 1 g.

Minced meat is stored for a short time and only in the cold.

The meat of healthy slaughter animals and poultry does not contain microorganisms. However, during the process of slaughter, toilet and carcass cutting, storage and transportation of fresh meat, various microorganisms can get on its surface and inside from the bleed knife and skin, from the gastrointestinal tract and lymph nodes, from the surface of hands and containers, from the surrounding air. Post-mortem changes occurring in the meat within 24-36 hours after slaughter lead to a decrease in the pH of the meat from 7.4 to 5.6, which helps to prevent the reproduction of microbiota in the meat. Some biochemical changes in meat (decrease in oxygen content, cessation of the function of the reticuloendothelial system, denaturation of proteins), on the contrary, contribute to the reproduction of microbiota in it.

COMPOSITION AND SOURCES OF MEAT MICROORGANISMS

Table 9.7

Chemical composition of meat and meat products, %

Source: URL: http://health-diet.ru/base_of_food/food_1516/ (accessed 12.12.2016).

The chemical composition of muscle tissue is very complex and quite stable. It contains up to 80% water, about 20% proteins, about 3% fats, extractive and mineral substances, enzymes and vitamins.

Muscle proteins have a high biological value. The protein myoglobin stains muscles red, and depending on its amount, the muscles of different animals have a color from pink (in pigs) to brown-brown.

Extractives include amino acids, purine and pyrimidine bases, creatine phosphate, creatine, creatinine, adenosine triphosphoric acid, and others.

Even in freezer during long-term storage, the meat is subject to microbial spoilage. The main representatives of the meat microbiota in such conditions are Clostridium perfringens and members of the family Enterobacteriaceae.

Bacteria of the genera are commonly found in red meat:Acinetobacter, Aeromonas, Enterococcus, Moraxella, Pseudomonas AndPsychrobacter. Representatives of the genera are often isolated from fungal microbiota and yeast:Cladosporium, Geotrichum, Mucor, Rhizopus, Candida, Torulopsis.

About 20 genera of bacteria are found in poultry meat.(Acinetobacter, Aeromonas, Enterococcus, Moraxella, Clostridium, Corynebacterium, Leuconostoc, Paenibacillus, Pseudomonas, Salmonella, Weissella) and up to 30 genera of fungal microbiota and yeast (most commonSporotrichum, Thamnidium, Candida, Debaryomyces, Rhodotorula, Yarrowia).

When analyzing a spoiled meat product, only some genera of bacteria, yeasts and molds are found out of many possible, and in most cases one or more of the genera found will characterize the spoilage of this type of meat product.

Microbiological studies of saw blades and block cutters showed: log o values ​​for TMF for meat - 5.1, for coliforms -

2.5, for enterococci - 3.2, for staphylococci - 1.12 and for micrococci - 3.26.

Despite the diversity of meat spoilage microorganisms presented above, only a few types of microorganisms dominate spoiled meat. Here it will be useful to turn to the internal and external factors that affect the growth of micro-organisms - contaminants. Beef, pork or lamb, as well as fresh poultry and seafood, have a pH within the growth range of most microorganisms. Nutrients and humidity are suitable to support the growth of all listed microorganisms. Although the ORP of whole muscle meat is low, it is usually somewhat higher on the surface of the meat, so obligate aerobes, facultative anaerobes, and obligate anaerobes tend to find conditions to grow.

In the considered types of meat and meat products, antimicrobial components in effective concentrations were not detected. The storage temperature is of the greatest importance for controlling the development of microorganisms. Therefore, these products are usually stored at low temperatures.

Sanitary cleaning and washing of carcasses before slaughter serve to reduce the contamination of meat and poultry. Immediately before slaughter, animals are usually covered with dust, dirt and fecal matter. The presence of microorganisms on the carcasses of slaughtered animals is not in doubt, and most of them are non-pathogenic, although pathogenic ones can also occur. There are many methods to reduce the quantity and diversity of microbiota on dressed carcasses and finished goods: stripping - trimming the remnants of the skin and surface tissues; washing - the use of water of various temperatures, supplied under pressure; the use of organic acids - adding acetic, citric or lactic acids to the water at a concentration of 2 to 5%; the use of other chemicals - adding hydrogen peroxide, chlorine dioxide or chlorhexidine to water; steam vacuum treatment - steam treatment for 5-10 seconds at 80°C or higher as the last stage of carcass processing; combined - the use of two or more of the methods described above.