Many food products are a favorable medium not only for preservation, but also for reproduction of microorganisms.
The entire food microflora is conditionally divided into a specific and nonspecific.
Specific microflora include strains of microorganisms used in the process of technological production of food (lactic acid products, bread products, beer, wines, etc.).
The non-specific microflora includes a random microflora, falling into foods in their preparation, delivery, processing and storage. The source of these microbes can be raw materials, air, water, equipment, animals, man.
Food infection with microorganisms can lead to people's toxicoinfection and other people. Diseases.
Microbiological food safety criteria are divided into four groups:
Sanitary-indicative microorganisms: BGPP, while the Bacteria of the genus Escherichia, Klebsiella, Citrobacter, Enterobacter, Serratia is taken into account.
Potentially pathogenic microorganisms: coagulazo-positive staphylococci, the bacteria of the genus Proteus, sulfuteutucting clostridia, B.cereus.
Pathogenic microorganisms, including Salmonella.
Microorganisms are indicators of microbiological stability of the product (yeast, mold mushrooms).
Sanitary and bacteriological research of food
Taking samples. Sampling is carried out sterile, sterile devices, in sterile dishes. Samples are placed in the appropriate container, seal. Transportation is carried out in refrigerators in the shortest possible time.
The sanitary and microbiological assessment of food products includes the definition of a total microbial number and the titer of sanitary microorganisms.
Determination of the total microbial number (OMC)
OMC is the total number of microorganisms contained in 1 g (cm 3) of the product. To determine it uses a method of multiple breeding.
Method of multiple dilutions. In the study of dense substrates, the jacket is crushed in a homogenizer or tritura in a mortar with quartz sand and prepare the initial suspension in dilution 1:10. A number of subsequent dilutions with such a calculation are prepared from the obtained suspension or the initial liquid material so that when having sowing the last two breeding on a Petri dish in agar rose from 50 to 300 colonies. Of the last two dilutions, 1 cm 3 are brought into a cup and poured 10-15 ml of molten and cold to 45 0 from MPa. Cups are incubated at 37 0 from 48 hours, the number of grown colonies count. ORC is determined with the dilution of the material under study.
Method of limiting breeding (titer). A number of tenfold dilutions are prepared from the initial liquid material until the presence of one bacterial cell can be assumed in the last test tube. Sowing is made in a liquid selective medium, followed by separation of microorganisms on a solid nutrient medium and studying their characteristics.
For the titer is taken, then the smallest number of substrate, in which one piece of the desired microorganism was detected.
Definition of sanitary microorganisms
Sanitary microorganisms characterize the product in terms of epidemic hazard.
The main sanitary and accurate microorganisms consider BGPP and for quantitative accounting use methods for determining quantity and titers. In this case, under the amount understands the determination of the most likely number (NVC) of the BGPP in a unit of mass or product volume.
Definition of NVC BGKP.
To determine the NVC from the liquid product or the initial suspension of the dense, the dilutions of 10 -1, 10 -2, 10 -3 are consistently made, of which 1 cm 3 are seeded in three test tubes with the Kessler medium for each dilution. After 24 hours of incubation at 37 0 C in tubes, changes in the color of the medium and gas formation are recorded. Depending on the number of sprouted, the tubes are determined by the NVC of the coliform bacteria.
Definition of titer BGKP
Prepare tenfold dilutions of the analyzed material and are sown on the Cessler's medium to identify the smallest amount of product in which there is an intestinal wand. The crops are thermostated at 43 0 s for 18-24 hours. From each tube, they are sowing on Petri dishes with the Endo medium so as to obtain the growth of individual colonies. The crops are incubated at 37 0 s - 18-24 hours, after which the strokes are made from the grown colonies, painted in gram. When detecting gram-negative sticks in strokes, the colonies are placed on the Giss Wednesday with glucose. The presence of gas formation in sowing test tubes indicates the presence of BGPP.
The titer is set to the smallest amount of product in which BGPP or standard tables are detected.
In the assessment of food products on microbiological indicators, it is necessary to take into account the possibility of detecting pathogenic and conditionally pathogenic microorganisms. Food is analyzed for the presence of salmonell, sulfituted clostridium, staphylococcus, a protest. With a broader study, products are examined on fungal flora.
For the study on Salmonella from the analyzed products, a suspension is prepared and seed on the accumulation medium (selenitic, chloride-magnesium broths). After a daily incubation at 37 0 C, they produced crossing on the Endo, Levin, Plagérey, or bismuth-sulfite agar. Next, the colonies are identified by taking into account the characteristics of growth on the media of GISS, RESEL, Olkenytsky and in the reaction of agglutination with monorceceptor serums.
To identify sulfituted clostrids, sowing the material under study in 2 test tubes with a Kitta Tarozzi medium, a wilson blaster or casein-mushroom medium is carried out. One test tube is heated at 80 ° C to destroy the accompanying microflora. Incubate crops at 37 0 from 5 days. In the presence of characteristic growth, it is sufficient to state a specific microflora in the smears and, if necessary, check the toxic formation in a biological system on white mice.
To identify staphylococci, the material under study is seeded on the yellow-salt agar. The crops are incubated in the thermostat of 24 hours. Suspicious in staphylococcus colonies are painted in gram, make them recreated on milk agar and conduct further identification of the dedicated culture.
To identify the protege, sowing the material under the underdeveloped agar by Schuhevich method. After a daily incubation from the upper edge of growth, strokes are made and, if there are gram-negative polymorphic bacteria in them, make a conclusion about the separation of the protege, if necessary, use biochemical and antigenic typing.
Food products may contain a variety of microflora. Natural and harmless food microflora is a complex biocenosis, which serves as a biological sewn from unwanted microorganisms. At the same time, individual types of microorganisms can affect the quality of food. With violation of the processing, storage or sale of products, these microorganisms may, multiplying to a significant level, lead to damage to the product and food poisoning.
The microbial spanking of products can occur by the type of fermentation, rotting, molding and decomposition of fats. Milk, cheeses and other dairy products are exposed to oily-acid fermentation due to the reproduction of sporing-forming anaerobic bacteria. With ϶ᴛᴏm, oil acid is formed, there will be an unpleasant taste and smell. Acetic acid fermentation leads to blasing of wine and beer. Alcohol fermentation caused by yeast is used in the production of alcohol, beer, etc. Local acid fermentation is used for the preparation of various dairy products.
Reduction is the process of decomposition of proteins to form fading gases caused by the impact of a set of microbes of rotting - the reason for the damage of many protein products. Mold mushrooms cause molding products when stored in refrigeration chambers, as mushrooms are resistant to low temperatures.
Of particular danger is infected with food products by pathogenic microorganisms, many of the keys are capable not only to continue to maintain viability in products, but also intensively multiply in them.
Microflora of food fats
There are natural fats for animal and vegetable origin and fatty products of industrial production (margarine, mayonnaise) The animal fats and vegetable oils contain a very slight amount of moisture and will be unfavorable for most microbes.
Butter contains a lot of moisture, microbes develop both on the surface of the oil, gas and inside it. Pinged and other bacteria, yeast, multiplying on the surface of the oil, decompose proteins and fats, lead to the formation of staff (bright yellow layer) with long-term storage of oil on the surface. Mold mushrooms are developing (odium, muc, etc.). Oil burglaries cause fatty bacteria. Gorky taste also give products to split proteins with proteolytic bacteria and micrococci.
Microflora eggs and egg products
Egg - Beautiful medium for reproduction of microorganisms. With oscillations of storage temperature, eggs are inherent "thermal" breathing. An increase in temperature leads to an expansion of the contents of the egg and the otsea of \u200b\u200bair from the path (air chamber) through the holes outside. When the temperature decreases, the air is sued inside the egg. Along with the air in the egg penetrate disputes of mold and various, incl. Pathogenic, microorganisms, intestinal wand, protein stick and other putrefactive bacteria, which are deposited on a superal shell holding them from penetration into protein.
Eggs obtained from a sick bird are infected with an endogenous way, that is, the infection falls into the contents of the egg before the formation of the shell. It is possible to penetrate pathogenic microorganisms into an exogenous egg (outside) through damage to the shell. In the protein of fresh eggs, microbes, incl. Salmonella, do not survive due to bactericidal action of lysozyme.
The presence of Salmonelle is most often found in the eggs of waterfowl. In adult ducks and geese, salmonellosis proceeds asymptomatic, but with ϶ᴛᴏ with the shell and yolk eggs are infected with salmonella.
The disputes of mold develop usually on the surface of the egg shell, forming a colony of various magnitudes, which look like a spots in the form of spots or cover the egg completely ("tumak") mold gives the egg an unpleasant mold smell, makes it unsuitable in food.
In the process of storage, protective ςʙᴏyasy lizozyme is reduced, and the microbes penetrate the egg. The reproduction of the rotor microflora causes the processes of rotting to form the decay of the eggs of the eggs, incl. and toxic, with an unpleasant taste and smell - ammonia, hydrogen sulfide, etc. This kind of damage is called "putrid decomposition". The use of eggs with such a vice is not allowed.
Egg powder May contain an increased number of different microorganisms, incl. Protane and intestinal sticks. Salmonella's high probability of getting into it is high, the egg powder should be subject to reliable thermal processing. Melange (a mixture of protein and yolk) due to the increased danger of salmonellosis is subject to freezing and is not used in public catering.
Microflora canned canned food
The safety criteria for canned food products will be the absence of microorganisms and microbial toxins that cause food poisoning. The greatestly hazardous food poisonings associated with the use of canned canned foods will be botulism and toxicoinfection caused by a perfretens chopper. Botulin stick and wand Perfengenses to sporing-forming anaerobic mesophilic bacteria from a group of sulfitreducing clostridium. The spores of clostridium and other gas-forming bacteria are able to withstand high temperatures during canning and multiply in canned food in the absence of oxygen to form carbon dioxide and hydrogen, causing blurred cans (bombing) in cannedish with high acidity (pH below 4.2) Klostridi spores do not germinate and not breed.
Vegetable and masonous canned food can be subjected to plane-acid damage - the product overlooking the product without bloating. This type of damage causes thermophilic aerobic and optionally anaerobic acid-forming bacillos.
With abundant infection of raw materials and insufficient sterilization in canned and semi-guesters (pasteurized, etc.), unfortunately inactive microorganisms are viable - count and molds, mold, yeast, golden staphylococcus, etc.
S. Aureus refers to negascinizing microorganisms, the reproduction of Kᴏᴛᴏᴩ, in canned matter is not accompanied by a bombing. In these cases, canned food can cause staphylococcal toxicosis and other food poisoning. The reproduction of staphylococcal and the accumulation of enterotoxin is suspended at low pH values \u200b\u200bin canned matter.
Microflora of grain products and bread
Microorganisms (bacteria, spores of mold mushrooms, yeast, etc.) fall in grain from the soil and with dust. The microflora of cereals and flour is determined by the microbial composition of the grain. In 1 g of grain products can be from several thousand to a million microbes.
Epidemiological importance has grain damage dangerous to people with mold mushrooms - ardines, mushrooms from the genus Fusarium and Aspsrgill.
The ardor and mold mushrooms from the genus Fusarium and Aspergill are able to allocate in the grain of mycotoxins, causing heavy food poisoning - mycotoxicosis. Mycotoxins can have carcinogenic and other dangerous impact on a person in very small quantities, they are not destroyed in products during heat treatment.
Flour is less than a rack to microbial damage than grain and cereals. In disruption of storage conditions, with moisturizes it is possible to increase the acidity of flour due to the reproduction of lactic acid bacteria, the reproduction of mold mushrooms and, as a result, the appearance of an unpleasant taste, smell or rugs.
When baking bread, most microorganisms dies, but disputes remain viable.
Wheat bread may be affected by "tight (potato) disease." Reproduction of the pathogen of the disease of the disease should not forget that you. SUBTILIS promotes low acidity, ςʙᴏ Eye wheat bread.
When cooled bread or when storing in bulk in conditions of high temperature and humidity, disputes should not forget that you. SUBTILIS germinate and blossomed by ςʙᴏim enzymes starch bread to dextrins. The bowkish first acquires an unpleasant smell of interpretuous melon or valerian, becomes sticky, then darkens and becomes drumming. Bread hit by "potato disease", for food purposes is not suitable.
Molding bread is caused by the development of Peniciilium Glaucum mushrooms (green mold), Aspergillus Glaucum (White Mold), Mucor Macedo (Golly Mold), Kum's disputes fall on the bread from the air after baking bread.
Microflora of vegetables, fruits and berries
On the surface of fresh vegetables and fruits there is a large number of different microorganisms that fall there from soil, water and air. The presence of leather, phytoncides, essential oils and organic acids prevents the development of microbes that cause damage to fruits and vegetables. Lingonberry and cranberries have special resistance to damage due to the content of benzoic and sorbic acids in them.
In case of damage to the skin of fruit and vegetable microbes, causing damage, multiply on the surface and fall inside the pulp. The processes of microbial deterioration contribute to the peat and long-term storage of fruits and vegetables. Rota and other spoken of vegetables and fruits are caused by mold mushrooms (phytoofluorosis and dry rotting of potatoes, black cancer of apples and pears, etc.), bacteria (wet rottato rot, black spotty tomatoes), yeast (damage of berries) Some types of fungi from genus Penicillium Spinning on apples, tomatoes, sea buckthorn berries, capable of highlighting the Pathulin's mycotoxin, which has a pronounced carcinogenic and mutagenic effect.
As a result of the use of fruits and berries contaminated soil, fruits and berries may occur, abdominal typhoids, cholera and other intestinal infections. Family outbreaks of dysentery with strawberries are known. The timing of the survival of pathogenic microorganisms and the eggs of helminths on the surface of vegetables and fruits can significantly exceed the timing of their storage to implementation. The use of vegetables, fruits and berries without thermal treatment can lead not only to intestinal infections, but also to yersiniosis, geohelminths, amoebic dysentery, etc.
Vegetables can be infected with rodents from rodents, from contaminated soil or water. With long-term storage in vegetable vegetables, Iracinium multiplies on the surface of vegetables and accumulate in significant amounts sufficient to occur in human disease. Most often, the cause of jewels is used in spring or early summer salads from raw vegetables of an old harvest.
Food products are a favorable environment for the development of microbes. Knowledge of the character of microflora foods and microbiological processes occurring in them are necessary for employees of catering for the organization of proper storage, processing of raw materials, cooking dishes and sales of finished food.
1) Microbiology of meat and meat products.
Muscles and blood healthy microbes do not contain. Meat is contaminated with microbes when processing it on meat processing plants. In the process of slaughtering of livestock, primary processing of the carcasters from the skin of animals, from the intestine, from the tool of slaughter and processing falls on the surface, and through lymphatic, blood vessels, penetrate inside the meat carcass. The intergeneration of the carcass increases during the transportation of them.
The development of microbes contributes to elevated temperature and humidity of the surrounding air.
Slows down the microbes and their development:
Low temperature carcass;
Fatness of the animal;
A large amount of fat
Having a crust of dried on the surface of the car
At 1 cm2 of the surface of the meat, up to several hundred thousand microbes are found, mainly such as: a rotten stick, salmonella, intestinal wand, mold mushrooms.
To preserve the quality of meat carcasters, the pieces of meat should strictly follow the conditions and the storage time of it.
Meat minced meat has microflora much abundant than pieces of meat, because The surface of the contact of the stuffing with air, the meat grinder increases, is the destruction of the fabric, partial leakage of meat juice, which creates favorable conditions for the reproduction and development of microbes. Therefore, storing stuffing should be short and at low temperatures.
Poultry meat is a great sanitary danger than animal meat, because The bird often comes half-stroke: with head, legs, internal organs, in which many microorganisms are detected. In addition, the bird, especially waterfowl (geese, ducks), in the intestine has many salmonella, which when processing (detecting the intestines) and the precern of the bird's fasting are interpreted by the entire carcass.
Special jobs are organized at catering establishments for home poultry.
Meat sub-products are severely contaminated with microorganisms, the same nature as at meat, as a result of entering them out of the outside environment during the life of animals (legs, tails, heads, ears) and elevated moisture (liver, nights, brains). Therefore, sub-products in public catering are always frozen and processed them in the meat shop in separate workplaces.
Sausage products are isolated by microbes as inside and outside. Inside, the microbes batons fall into the sausage mince, which is seized in the process of its preparation. In the process of thermal processing of sausages (cooking ferry, smoking with hot smoke), most of these microbes die. Bacill disputes remain viable, among which Botulinus disputes are particularly dangerous. When storing sausages, it is necessary to comply with the conditions, storage time.
The least rack when storing a group of boiled sausages, potions, jelly, especially cooked from the lower varieties of meat or from a highly immunified microbes of raw materials (cropping, offal). In addition, these products have increased humidity.
Semi-specific, varenocharged, smoked sausages are more resistant stuffing due to the smaller microbes of high-quality raw materials, less humidity, a large salt content and smoke treatments during smoke.
2) Fish and fish products microbiology.
Fish is a perishable product, because It is severely immaculated by microbes outside, inside the intestine and in the gills of the head. After catching, all these microbes penetrate the fissure of the fish, causing it damage. A significant seamation of microbes of fish fabric comes from patients of fish instances during their cutting, processing and storage.
Micrococci, sarcines, (spherical bacteria) shields are found in the fish. The botulinus wand is especially dangerous, causing severe poisoning - botulism. To prevent this poisoning, the catchy large fish (sturgeon) will immediately waste and frozen, preventing this highlighting of a botulinus to the human life dangerous to the human life.
Fresh-frozen fish is stored longer, because Microbiological processes are suspended or slowed down, causing sometimes development on the surface of fish of mold fungi in the form of single point colonies.
The freshness of the fish is judged by smell, gills and tissue consistency.
Salted, dried, smoked fish more rack when stored, because The production process of its (salt, dehydration, substance of smoke) creates unfavorable conditions for the development of microbes.
Difficult toes of the sea (crustaceans, bivalve mollusks, cephalopod) are immaculated by microbes of sea water, ya, from the intestines of animals themselves, which makes them perishable, easy to rot under the action of grinding microbes. There are cases of food infections (typhoid) and food poisoning when eating meat of raw mollusks (oysters).
3) Microbiology of sterilized canned canned canned food.
Hermetically closed canned food from vegetables, fruits, meat, fish, subjected, sterilization with the observance of the installed mode (time, temperature), microbes do not contain and storage racks.
However, it is known that canned canned cans can cause microbial poisoning and product damage in them. This is due to the fact that spore bacteria are found in canned matter, with higher resistance to sterilization regime: spores of potato sticks, oil-acid bacteria and botulinus disputes. Having retained the viability, these microorganisms are isolated as a result of the development of carbon dioxide, hydrogen, hydrogen sulfide, which are absorbed by the cans. Such a phenomenon is called a biological bombing.
Bombing banks can be poisonous due to the content of toxin highlighted by the botulinus stick, and are subject to destruction.
Some disputes of anaerobic microbes that preserved life after insufficient sterilization can spoil the contents of canned food without gas formation, without external changes in banks. Such a damage can be detected at the opening of the can and is called a flat drying. This is observed most often from canned with weakly acidic content: green peas, meat and sausage canned food, canned baby food.
4) Milk microbiology and dairy products.
Milk is an excellent environment for the development of microorganisms that fall into it from the udder and animal wool, from the hands of the milk, litter of the catal courtyard, inventory, etc.
In 1 ml of milk, several hundred thousand microbes are found. When the milk is cooled to + 3 ° C, the number of microbes decreases under the action of bactericidal substances of freshly beyond milk for 2-40 hours. Then there comes the rapid development of all microbes with the predominance of the development of milk-acid bacteria. Milk accumulates lactic acid and antibiotics allocated by these microbes, which leads to the destruction of all microorganisms, and milk-acid bacteria. Milk scores, favorable conditions are created for the development of mold fungi, and then putrefactive microbes. There is a rotary damage of milk.
In pasteurized milk (heated to 63-90 ° C), almost all milk-sour bacteria and bactericidal substances perish, but the disputes of microbes are saved. Additional milk seamation with rotten or pathogenic microbes leads to a damage of milk and makes it dangerous to health. Therefore, pasteurized milk requires a certain storage mode (+ 4 ° DDO36ch).
Sterilized milk (heated to 140 ° C in a few seconds), cooked from fresh high-quality milk, microbes does not contain and therefore persists in hermetic packaging up to 4 months.
Milk can get pathogenic microbes - pathogens of dysentery, typhoid typhoids, tuberculosis. Therefore, in public food, milk will definitely boil.
Dry milk-unfavorable environment for the development of microbes, although it remains all the disputes of Bacill, heat-resistant Non-famous types of micrococci, streptococci, some milk-sour bacteria, mold mushrooms. These microbes can cause molds with strong moisturizing milk, writing it.
Condensed milk persists well, because A large concentration of sugar and sterilization kill most microbes. Highly immrange raw materials from which condensed milk is made can lead to a waiver or rotting it.
Dairy products contain microorganisms that are part of the factory starter, yeast - for kefir and Kumsa. In addition, microflora of sour milk products depends on the microbes of milk and the sanitary condition of the equipment.
5) microbiology of food fats.
Creamy oil containing plenty of water, proteins, carbohydrates, is immunified by hundreds of thousands of rotor, milky-acid bacteria, and in sour butter, it is also contained and aromatic-forming cocci. The fat trampling bacteria can cause fats damping, giving oil a bitter taste. Therefore, butter is stored for a long time (up to 10 days) at a temperature of + 4 ° C.
Fats Genesed animals and vegetable oils containing little moisture (up to 0.3%), racks to the effects of microbes, and therefore well stored.
6) Microbiology eggs and egg products.
The egg is immaculated by microorganisms during the suspension. The internal contents of the egg of a healthy bird remains for a long time without microbes, thanks to the natural immune substance of eggs - lysozyme, dried film on the surface of the egg and a superal shell that prevent penetration of microbes inside. In the process of storing, the protective forces of the eggs weaken, the suprupny and superal shell are destroyed. Microbes (intestinal stick, protea, staphylococci, mold mushrooms) through the pores penetrate the egg, exposing it to damage it: rotten the protein with the release of unpleasant odor (ammonia, hydrogen sulfide), mold with the appearance of black spots under the shell.
A sick bird, often waterfowl, in the intestines may contain salmonella, the squeezing egg inside when it is generated in the body of the bird and on the shell. Such an egg causes people a disease - salmonellosis.
Melange (a mixture of protein and yolk) is a perishable egg product, so it is always in public food in a frozen form and is used only in the dough, products from which are subjected to long-term thermal processing. The melange arriving in public food, according to the standard should not contain pathogenic microbes and intestinal sticks.
The egg powder contains several hundred thousand microorganisms in 1 g of the product, including the intestinal wand, salmonella, a rotten stick (protea). Egg powder should be stored dry (moisture up to 8.5%), and in a divided form to quickly expose thorough heat treatment at high temperatures.
7) Microbiology of vegetables, fruits and products of their processing.
Fresh vegetables, fruits are abundant are isolated by microorganisms falling on them from soil, water and air. Due to the skin, organic acids of juice, glycosides, essential oils, phytoncides, fresh vegetables and fruits have a resistant immunity, which is enhanced on the surface of vegetables and fruits, yeast, acetic acid, milk-sour and other bacteria.
The damage of vegetables and fruits occurs as a result of overheating during long-term storage and impaired integrity of their cover. The microbes are embedded inside the pulp and cause the mold first, and then rotting the fruit.
The surface of all vegetables and fruits can be pathogenic (pathogeful) bacteria causing dysentery, abdominal typhoid, cholera. Therefore, vegetables, fruits, which are in the food in the raw form, require careful wash.
Sauer vegetables, fruits contain milky-sour, acetic acid bacteria, yeast, which form a large amount of dairy, acetic acid, ethyl alcohol, carbon dioxide, ethers that give the sauer products a pleasant taste and aroma.
Storage of sauer vegetables and fruits at low temperatures (about + 3 ° C) contributes to the preservation of their quality.
8) microbiology of grain products.
Crupes, flour are mainly immunified by bacteria, mold mushrooms, yeast up to 1 million cells in 1 g of products.
Finding out of the soil, dust, the disputes of mushrooms are well preserved even with low humidity of cereals and flour (up to 15%) without affecting the quality of products. When moisturizing grain products, spores of mold mushrooms germinate, develop, destroying carbohydrates, proteins, fats Crupes and flour, there is an unpleasant taste, smell and commerciality of these products. Milk-sour bacteria cause increased acidity of flour.
Bread and baker produce with yeast and milky-acid bacteria, which ensure the porosity of the bread due to the resulting carbon dioxide, taste and aroma due to the resulting lactic acid, alcohol, esters and other substances.
Microorganisms falling into the dough with flour, from the air, from the equipment, die when baking products, but their disputes remain and in the future spoil the quality of bread in violation of sanitary and hygienic storage rules.
Finished baked bread with high humidity and storage temperature can be additionally intermittent with microorganisms and be selected in the form of potato, chalk diseases, mold.
Questions for self-control
1. Microbiology of meat and meat products.
2. Microbiology of fish and fish products.
3. Microbiology of sterilized canned canned rooms.
4. Microbiology of milk and dairy products.
5. Microbiology of food fats.
6. Microbiology eggs and egg products.
7. Microbiology of vegetables, fruits and products of their processing.
8. Microbiology of grain products.
1). MEAT. In the first hours after slaughtering livestock, the deep layers of meat are practically sterile. On the surface of the carca, the species composition of microflora is diverse - this soil bacteria (Cockki, Bacillus, Klostridia), Bacteria intestines, as well as Mold mushrooms. Spinning and accumulating on the surface of the carcass, they gradually penetrate the thickness of meat and cause damage processes.
When storing meat in microflora cooling chambers, it remains unchanged for some time as a result of formation on the surface of the carcass of the raised layer, which prevents the development of microorganisms. In the future, the microflora undergo qualitative changes: the mesophils die and psychrophils are developing, which the prevailing species become row-shaped bacteria, capable of multiplying at a temperature of 0 ¸ -5 0 C, and separate species even at -8 ¸ -9 0 C. in aerobic (in the presence of oxygen air) conditions of storage of chilled meat These bacteria are the main causative agent of its damage. Initially, individual colonies grow on more humid surfaces of the product, then a solid mucosity is formed gray, greenish or brown, the smell and taste of meat changes.
Mold mushrooms are the main pathogens of meat damage under storage conditions at temperatures -4 ¸ -9 0 S. These mushrooms not only change the appearance and smell of the product, but also cause a deep decay of proteins. Due to the active splitting of lipids, the product is bar. For some negative temperatures, mold mushrooms grow even on frozen meat.
2) BIRD. A feature of the microflora of poultry meat is the possibility of the presence of bacteria from the Salmonella group that can cause food toxicoin intake. In this regard, the carcass of waterfowl is especially dangerous.
3) FISH. Microflora fish are represented disporated and non-planned chopsticks, micrococci, sarcines, as well as inhabable mold mushrooms and yeast. As a result of the storage of fish at reduced temperatures, mesophilic forms of bacteria die, and psychrofils develop. The northern seas and rivers are more infected with psychrofyls, mold mushrooms and yeast. With a sharp decrease in temperature, the growth of bacteria is suspended, and even psychrophyls begin to multiply only after a while. If at 18 0 with the amount of bacteria reaches 10 8 - 10 9 per 1 g of fish during the day, then at a temperature of 0 ¸ -2 0 with growth observed only on the fourth - fifth day.
Ice, sea water and brines can be sources of microorganisms. In a frozen in a lively or very fresh form of fish, microorganisms develop on the surface. In the thickness of the muscles they are missing.
4) Milk and cream. Here the reproduction of microorganisms is faster than on the surface of solid products. As a result of infection, raw milk may contain different microflora: local bacteria, dispute and non-food sticks, bacteria of the group of intestinal sticks, micrococci and staphylococci.
The development of milk microflora occurs in several phases. Bactericidal phase It is characterized by the fact that after the milking cows, microorganisms in milk do not develop and even partially die away from the action of special substances. The immediate cooling of milk after the milking can extend the bactericidal phase to 24 to 28 hours. Mixed Microflora Development Phase It is characterized by the development of microorganisms in milk. Depending on the storage temperature in milk, thermo-meson or psychrofils begin to prevail. Phase development of lactic acid bacteria It is characterized by a rapid increase in acidity as a result of lactose fermentation into lactic acid. If the environment is alkaline in milk, then conditions for development will be created pinged and oily acid bacteria And the milk will become unsuitable for use.
If milk and cream are stored at low temperatures, the reproduction of lactic acid bacteria is delayed. Under the action of them with relatively long-term storage of milk, proteins and fats are splitting with the formation of bitter and unpleasant product smelling. Sometimes, during refrigeration, the milk may appear mucus, most often caused by psychrofils.
Fruits and vegetables can be a source of pathogenic and toxic microflora. Especially common pathogens of intestinal diseases that do not die completely with long-term storage. Products containing little organic acids can be exposed to both mold mushrooms and bacteria.
When storing frozen fruits, vegetables and berries, the bacteria gradually die. First of all, non-sports chopsticks are dying, including the bacteria of the intestinal group, more stable micrococci, staphylococci and dispute. When thawing these products, they begin to multiply intensively, leading to a sparrel of the product.
In addition, vegetable products contain phytoncides of various activity. Such vegetables, like onions, garlic and horseradish, distinguish bactericidal substances that kill disinteria, intestinal sticks, staphylacocci, as well as cholera vibriums. The phytoncides of the peel and the pulp of citrus, bananas, pomegranates and apples, as well as berries in detail on various bacteria, mold mushrooms.
