Chilled and frozen foods

General characteristics of microorganisms in frozen

                                                   GENERAL DESCRIPTION OF MICROORGANISMS
The microflora of foods at refrigerated storage may be represented by bacteria, actinomycetes, molds and yeasts.
Bacteria - are single-celled organisms, whose dimensions are expressed in microns or tenths of a micron (μ = 0,001 mm). The shape of the cells of the bacteria are spherical, rod-shaped and crimped. On food bacteria are found primarily spherical and rod-shaped. The bacteria are called cocci spherical shape. Depending on the location of the cells are distinguished: micrococci (Micrococcus) - from the sensible-cells; diplococci (Diplococcus) - paired cells; streptococci (Streptococcus) - cells in the form of chains; staphylococci (Staphylococcus) -skoplenie cocci in a bunch.
Rod-shaped bacteria are distinguished primarily by the ability to form spores. Spore - is the intracellular formation of rod-shaped bodies of many bacteria. Disputes usually appear under adverse propagation conditions. They are resistant to the harmful effects of the environment. Under favorable conditions, spores germinate and the bacterial cells are formed. Spore-forming bacteria called bacillus.
Some rod-shaped bacteria have flagella or cilia with which they move. There are moving and still bacteria. The concept of the bacteria used in a more narrow sense - as the bessporovye rod-shaped. Spherical and rod-shaped bacteria reproduce by dividing into two cells of the adult equivalent "daughter." Under optimal conditions for the reproduction process of growth and division of bacterial cells lasts 20-30 minutes.
During the multiplication of bacteria on solid media or product formed cell mass, which becomes visible to the naked eye. This cluster of cells called colonies. By merging, the colonies form a film or other mucous consistency. The substrates are liquids turbidity, flake, pellet or film. Bacteria are distinguished and determined by a number of morphological and biochemical parameters. By morphological parameters include the shape, size; for rod-shaped bacteria -
spore formation, mobility, presence and location of flagella and cilia, the type, the color of the colonies, medium staining and so. d.
By the ability to take and hold the main paint bacteria are divided into two groups. Bacteria possessing such capability are called Gram-positive (Gram researcher named); not having the ability to be painted - Gram. 

PinicilliumFig. 1. Mould: a - Penicillium, 
Cladosporium herbsb - Cladosporium herbarum, 
Thavmnidiumβ - Thamnidium
This indicator is one of the main bacteria at recognition.
By biochemical parameters include the ability to change the carbohydrates, proteins, fats, the ratio of oxygen to the air, and others. The bacteria are also divided on the basis of pathogenicity and toxigenicity.
The species and number of bacteria belonging group particularly toxigenic pathogenic and can be determined only by their reactions with serum (serum) blood (serotypes) obtained from the organism who underwent disease or poisoning.
In recent years, the characteristics of microorganisms added to their attitude to antibiotics.
Only a few bacteria can be identified by shape or by any other characteristic. The definition of many species can be made only by a combination of various characteristics. 
Molds are more complex in structure. Typical molds have a vegetative body, or mycelium, which is a loose or dense felt-like plexus of thin filaments - hyphae. Aerial or fruiting hyphae (sporangiophores or conidiophores) rise from the mycelium, on the tops of which fruit bodies with spores or conidia are formed. From bacterial spores, they differ in the nature of education and properties. Molds multiply by dividing hyphae, spores and conidia. On products with refrigerated storage, molds of the penicillium genus (Penicillium), mucor (Mucor, Rhizopus and Thamnidium), cladosporium (Cladosporium) and others are most often found.
(Fig. 1 and 2).
The mold penicillium have racemose form conidiophores.
On the products and environments, they are growing at the beginning of development in the form of colonies, or whitish plaque. Later they acquire their characteristic color.Penicillium glandicola For many molds of this kind it has blue-green color.
Mukorovye molds are characterized by a cobwebby or furry coating of grayish-smoky color rising above the substrate, with black or brown spotted sporangia, which are small, but visible under the magnifying glass. In the form of fruiting in the form of heads, these molds are called capitate. Of this group, mold tannidium (Thamnidium) is of great importance, although it is less common and less common than others. With the growth of this mold on meat there is an unpleasant smell. Microscopically, tannidium differs from mukor by the presence of two types of sporangia: a large, main sporangia on top, and small sporangia (sporangioles) on lateral branches.
Of great importance in the refrigeration storage is mold kladosporium gerbarum (Cladosporium herbarum). On the surface of this substrate in the form of mold growing plaque velvety dark colored bottle. With the growth in the meat and dairy products, it forms a dark, almost black spots, deeply penetrating into the substrate. This is especially noticeable on the frozen mutton.
For other molds it will be made in the characterization of the microflora of certain types of products.
Due to the contact with the soil particles and dust foods may be infected and actinomycetes (Actinomyces), or fungal radiant which on further features similar to those of bacteria, on the other - with the molds. Body
It is a filamentous actinomycetes formation (diameter about 1μ), diverging from a central point of growth in the form of beams (Fig. 3).
On nutrient media initially actinomycetes grow in dense, fused with the substrate leatherback colonies. Later on in the majority of these colonies of actinomycetes formed a well-developed aerial mycelium (fluffy or velvety and powdery) form spores similar to those of mold spores.
The growth of many actinomycetes is detected by the characteristic earthy smell.
Yeasts are single-celled organisms, most often oval or round shape. According to the economic value of wild yeast and distinguished cultural. Wild yeast, preferably a round shape, are found on the products under refrigerated storage. Cultural yeast used in the fermentation industry.
budding yeast
yeast cells
larger than most bacteria. Wild yeasts reproduce by budding, in adult cells, small cells are formed in the form of kidney. Become adults, they give a new kidney, and so on. D. From one parent may spun off a few cells (Fig. 4),5              
               psychrophilic microorganisms

Microorganisms can grow and multiply in a very wide range of temperatures. However, for each group (genus or even family) there is a certain upper and lower temperature limits of growth, as well as the optimum temperature at which the rate of reproduction is greatest.
In relation to temperature, all microorganisms can be subdivided into three groups: thermophiles, mesophiles, and psychoorganisms. Thermophiles breed at temperatures from 20
Active growth of different groups of psychrophilic microorganisms on the meat, depending on the temperature, with humidity 80%

The timing of growth days
Temperature, ° C bacteria molds yeast Torul aktynomy- Time poyaleniya damage signs, days The composition of the microflora
-0,5 7 14 6 5 14 Mould: tamnidium, Aspergillus, Mucor, oospore; Yeast: rodotorula; bacteria: Pseudomonas, ahromobakter, micrococci
-1,1 7 14 6 6 24 Mould: the same and R. nigricans; bacteria: Pseudomonas 20%, ahromobakter 70%, flavobacterium 10%
2,7ч-1,6 13 30 25 25 50 Mould: the same; bacteria: Pseudomonas 50%, ahromobakter 50%
-3,3т-2,2 25 25 25 43 Mould: tamnidium, Aspergillus, R. nigricans; Yeast: Togrul; bacteria: ahromobakter 100% and aktinominety
-5,5ч-4,4 135 65 60 No 155 Molds: tamnidium, aspergillus, rhizopus, pericillium, sporotriumum, cladosporium; yeast: white, bacteria: achromobacter
-7.2ч- -6,1 167 65 105 No 135 The same
7,7 hours6,6 No 144 No No 190 Uncertain white mold
9,4 : -8,3 No 144 No No 170 Spot the growth of white mold
- 11,1ч - 10 No 144 No No 260 Uncertain white mold
-12,2ч11,1 No No No No St. 500
14,4ч- -13,3 No No No No St. 500
-17,8 No five No No St. 500
-20,2 No No No No St. 500

up to 80 °, optimum around 50 — 55 °; mesophiles - at temperatures from 45 to 5 — 10 °, optimum around 24 — 40 °; psychrophils - from 25 — 35 ° to —5 -s 10 °, optimum around 10 — 20 °. During refrigerated storage, psychrophilic microorganisms are of the greatest interest.
Temperature minimum growth of different groups of psychrophilic microorganisms shown in Table. 1.
bacteria. Many indisputable gram-negative motile and immobile bacteria are considered to be psychrophilic. In terms of their prevalence and abundance on food products during refrigerated storage (chilled meat, fish, milk, eggs and non-standard meat, fish, dairy and egg products), bacteria belonging to the genera Pseudomonas and Achromobacter occupy the first place. Flavobacterium (Flavobacterium) products are found in much smaller amounts. More rarely and in small quantities - alkaligenes (Alcaligenes), aerobacter (Aerobacter) and some micrococci.

Multidrug resistant Pseudomonas aeruginosa 65453743 1Fig. 5. Pseudomonas (micrograph)

The bacteria Pseudomonas and Achromobacter grow on mediums and products in the form of translucent with a glossy surface of the colonies or film, or mucus grayish, yellowish and brown. A number of pseudomonas species (fluorescent bacteria) cause a change (greening or browning) of the medium color.
According to the modern classification [1, 2], Pseudomonas includes all dyed and non-staining medium motile bacteria with a polar flagellum (Fig. 5).
 Differentiation between staining and non-staining medium Pseudomonas is recommended for antibiotics penicillin and terramycin, in accordance with the following scheme

  Penicillin 2,5 mejd. U. cin 10 y
chromogenic Pseudomonas        — +           +
Do not forming pigment Pseudomonas      —       +

Note. Signs indicate: -nechuvstvitelnye; + Sensitive; ++ Very sensitive.
Colorless and non-staining medium, immobile as well as motile bacteria, moving with the help of flagella over the entire surface of the body (peritrich), are classified as Achromobacter
Table 2. 
Characteristics of the different families of non-spore bacteria to antibiotics and mobility [3]

family Penicillin (2,5 mejd. U). Streptomycin (80) Xloram- fenikol (100) Mobility
Pseudomonadaceae + OR + Movable (flagella on
++ lar)
Achromobacteriaceae + ++ ++ Mostly nep
moving or moving
nye peritrichous
gram-positive + + Moving peritrichous
Gram-negative + + or still

A distinctive feature of Pseudomonas and Achromobacter among other non-spore gram-negative bacteria is their relationship to the three antibiotics (Table 2).
The bacteria Pseudomonas and Achromobacter differ in their treatment of antibiotics tetracyclines. So, on poultry not treated with antibiotics and treated with oxytetracycline, during storage at 1 °, non-staining Pseudomonas medium prevailed; on the chlortetracycline treated bird, Achromobacter [4] were predominant.
Table 3. The relative sensitivity of different bacterial species to gamma-rays from the source So00 (1640 p / min) [5]

Relative sensitivity of different bacteria to gamma rays from Co00 source (1640 r / min) [5]
organisms Exposure to 63% solution of cell death, min.
Ps. fluorescens 2,8
Aerobacter aerogenes 4,8
Escherichia coli 6,5
Micr. pyogenes var. albus . . 13
Corynebacterium xerose . . . 18
Micr. pyogenes var. aureus . . 20
Bacillus thermoacidurans . . 39
Streptococcus faecalis ... 28

The unequal attitude of various bacteria to antibiotics, even if they belong to the same group - psychrophilia, shows how practically it is important to determine at least the generic affiliation of a microorganism.
Psychrophilic microorganisms are relatively unstable to radiation (tab. 3, 4),
Table 4. Changes in the qualitative composition of the bacterial flora (%) on irradiated fish (M rad) during storage at temperature 0 ° [6]

Change of qualitative composition of the bacterial flora (in %) on irradiated fish (M rad) in during storage at a temperature of 0 ° [6]
The name of the bacteria Undressed after filetirovaniâ irradiated 0,25 M rad after treatment Cured aureomycin after immersion Aureomycin treated and irradiated 0,25 M rad after treatment
through 1 day through 23 days through 1 day through 21 day through 1 day By through 6 days via
23 day 20 days
Pseudomonas .... 40 72 3 99 32 7 2 97
Achromobacter ... 30 13,5 63 35 6 2
Flavobacterium . . . 11 8 5 1
Corynebacterium . . . 6 1 6 1 12 8
Micrococcus   1 20 5 2 2
Yeast   1 67 92 1
Different   12 13,5 10 9 2 2

The bacteria Pseudomonas and Achromobacter are characterized by the following temperature indices: the minimum growth temperature is from 0 to —5 °, the optimum is from 20 to 10 ° and the maximum is from 35 to 25 °. Some species can grow on non-frozen environments up to —8 - * 9 °. At a temperature of 63 °, the psychrophils die within 30 min.
Most of the bacteria in these groups are aerobes: under anaerobic conditions, their growth slows down or stops altogether. Growth is also delayed with a decrease in pH (below 5,5) and with 5 — 8% NaCl [7] in the medium. Many species of these bacteria are able to thin the meat-peptone gelatin. In minced meat stored until spoilage at 0 °, bacteria diluting gelatin were contained to 75%. Approximately the same number of bacteria diluting gelatin was contained in the microflora isolated from sea fish [8].
Many species of Pseudomonas and Achromobacter have the ability to break down proteins and occupy the third place in the series of proteolytically sensitive bacteria (after anaerobic bacilli and protea). Bacteria Pseudomonas and Achromobacter are the main causative agents of spoilage of protein products when they are stored chilled. Damage to products, manifested in the formation of foreign smell, can be caused, however, not only by proteolytic bacteria, but also by those of this group that do not possess proteolytic ability [9].
Pseudomonas is characterized by other signs. Some species ferment glucose, sometimes with the formation of gas. Some species actively break down fats. Some of them, with alkalization or acidification, cause coagulation of milk, others do not change it, etc. Pseudomonas putrefaciens are among the main causative agents of spoilage of protein products (milk, dairy products, fish, meat) during refrigerated storage (Ps. Putrefaciens) pseudomonal Fraga (Ps. Frags) and pseudomonal fluorescens (Ps. Fluorescens) [7, 10, 11].
Ps. putrefaciens is characterized by the reddish-brown color of deep colonies on agar and the absence of pigment, which dyes the environment, the ability to thin the meat-peptone gelatin, the absence or poor growth at 37 °, the rapid recovery of litmus milk and the strong smell of decomposition. In agar with sugar, when sowing, some cultures gave acid in the lower layers and alkalinization on the surface. Adding salt to the agar medium to 4 — 5% improves growth. Above 8% growth retarded. In butter, they cause a loss of flavor as a result of the destruction of diacetyl, and then give the smell of decomposition. Like all psychrophilic bacteria, Ps. putrefaciens are easily destroyed when heated. In milk at 61,5 °, they collapsed within 2 minutes, and most within 1 minutes.
  Ps. fragi, unlike Ps. putrefaciens, causes coagulation of milk. Ps. Fluorescens is characterized by a pronounced ability to release green pigment into the substrate. These bacteria liquefy meat-peptone gelatin, grow poorly or do not grow at all at 37 °, cause alkalinization of milk without coagulation.
  Bacteria of the genus Achromobacter may slightly acidify the milk, but not enough to coagulate. Usually the reaction of the milk remains unchanged or becomes alkaline. They can form acid from hexoses (glucose) without gas evolution.
  Close to the genus Achromobacter are Alcaligenes bacteria. Ot'Achromobacter They differ in that the milk and basified not form acids from carbohydrates [2].
  Psychophilic bacteria are found in soil, water (fresh and especially in the sea), in the air. At the enterprises, they disseminate equipment, tools, and containers; they are contained in large quantities on products when they are received for storage. Psychrophilic bacteria actively reproduce on products with low acidity: meat, fish and non-acidic dairy and vegetable. In acidic products - berries, fruits, tomatoes, lactic acid products - only a small fraction of psychrophilic bacteria actively reproduce.
   The content of psychrophilic bacteria in products is illustrated by the following example.
   Of the bacteria isolated from sprat, 7% grew at 90 ° from the number growing at room temperature, 4% at 77 °, 0% at 66 ° and 2% at 64 °.
The composition of the microflora of meat semi-finished products obtained in the distribution network, according to the ability to reproduce is shown in Table. 5.
Composition psychrophilic bacteria on different products can be seen in Table. 6.
  Mould. Psychrophilic microorganisms include the majority of molds. Molds grow quite actively on frozen foods. The most common among them is Pénicillium, then Nucor, Rhіzorus, Thamnidium, Sladosorium and others. The last two types of molds cease to reproduce only about -10 ° [15].
T able 5. The composition of the microflora and minced cutlets for the ability to grow at different temperatures (in% of the number of bacteria growing at ambient temperature)

Meat semi-finished products crop cultivation temperature, ° C
10 б 2,5 0
№ 2   > 69 69 34 30
№ 3 87 75
№ 5 24 22 19,8 13,5
№ 6 > 87 87 64 60
№ 1 89 24 19 11
number 2 100 55 43 32
№ 3 100 100 67 55

Mold fall on products during manufacture and storage at refrigerated.
Table 6. Composition of psychrophilic bacteria in different product (in%)

Pseudomonas Achromobacter Alcaligenes Flavobacterium Micrococcus Coll-aerogenes Corynebacterium Different
Raw milk is stored at 3-5 ° within 1-3 days  . 15,1 45,3 16,8 19,5 з;з
The oil (gram-negative bacteria affecting milk)   -21 41 27,6 3,7 5;8
The surface of the two kinds of flat fish (the North Sea) [12] 53-60 13-14 6-8 5-9 1-3 1-2 11-14
Freshly caught cod (North Sea) [13] 51,5 41,3 1,5 0,7 1 4
Surface birds [14]: at the beginning of storage. > 35— -25 -10 - 5. -10
0 -95 40 <1 <1 <1 -5

Mould as yeast proliferate mainly in acidic foods (berries, fruits, juices, milk products), as well as meat and fish. Being aerobic, they grow mainly on the surface. In the presence of air, they can also grow in the deep layers of the product; for example, in poorly formulated oil, they are able to develop inside the monolith.
     Yeast and mold are not resistant to heat. Thus, spores (and conidia) of molds are destroyed at temperatures well below 100 °. Spores of many types of mold died off in milk during 30-minute exposure at a temperature of 55,5 °; some were squeezed out at 60 °, but at 62,7 ° they died off completely. According to other data, at 62,7 ° they died off within 30 seconds. few mold spores, with 68,3 ° during the same time most, and with 74 — 80 °, all [10] died.
   The presence of mold in products subjected to pasteurization, indicates poor implementation or subsequent contamination. Some molds are active against proteins and fats. Oidium lactis is characterized by its large lipolytic capacity. Some molds use sugars and oxidize organic acids.
   Yeasts and actinomycetes. Psychrophilic yeast - torula (“wild yeast”), like psychrophilic bacteria, is indisputable. Psychrophilic yeast grows on all products stored on refrigerators. More often they occur and multiply faster in acidic foods. Actinomycetes grow at temperatures up to —2; —3 °.
                                       mesophilic microorganisms
Mesophilic microorganisms do not multiply under conditions of cold storage of products; temperature minimum of their growth 5 — 10 °. These include spore-forming aerobic and anaerobic bacteria, many coccal forms, lactic acid bacteria, etc. This group also includes pathogenic bacteria, bacteria of the group of Escherichia coli, Proteus, Staphylococcus, fecal streptococci, etc.
  Higher temperatures 0 ° cease to multiply the cultural race of yeast and certain types of mold (Aspergillus niger).
Mesophilic microorganisms in cold storage conditions cannot cause changes in the commercial quality of products; Of this group, the most important are those that can adversely affect human health. According to their content in a number of products, the quality of the latter is judged from a sanitary and hygienic point of view. Some of this group of bacteria (for example, salmonella) are pathogenic; others (eg, E. coli) are indicative of the possible presence of pathogenic bacteria, and sometimes they themselves can cause disease; still others (for example, some strains of staphylococcus and botulinus bacilli) can cause the formation of toxin products. Without causing changes in the product at low temperatures, these bacteria begin to show activity with increasing temperature.
  The need for special attention to these bacteria is caused by the difficulty of identifying both themselves and their metabolic products (toxins).
    Coliform bacteria. As a sanitary and hygienic indicator of foodstuffs, bacteria of the group of E. coli or typical (fecal) E. coli are most often taken.
   These bacteria are contained in the intestines of humans and animals, whence they enter the environment, and when sanitary rules are not followed, they are also in products.
   The bacteria of the group of E. coli are divided into a number of species. Of these, the main ones are typical (fecal) E. coli Bact. coli-commune, or in American terminology Escherichia coli, and Bact. coli-aerogenes, or Aerobacter aerogenes. Determining the species of these bacteria is difficult. It is more expedient to determine in products the content of the entire group of these bacteria, without establishing the type.
Bact. coli-commune is different from bact. coli-aerogenes at minimum temperature. The first ones stop growing near 5 °, the second ones are closer to 0 °.
With a large accumulation of Bact. coli-commune in the product (for example, in milk) false lactic acid fermentation often occurs, and Bact. coli-aerogenes - and mucus formation. A typical E. coli causes the breakdown of peptones to form indole. In carbohydrate foods, Escherichia coli strongly increase acidity (typical Escherichia coli to pH <5,0 and coli-aerogenes to pH ~ 5) "however, they are unstable to acidic environments and die off rather quickly in acidic foods. With slight heating, they are destroyed. So, according to Ayrs and Johnson, out of 174 strains of bacteria of the E. coli group at 62 ° for 3 min. survived 12 (7%); according to Tanner from 23 at 62 ° for 30 min. one strain survived; according to Stark and Patterson from 505 cultures at 60 ° for 30 min. died 487 (96%); of the remaining 18 at 61,5 ° for 30 min. 14 strains were destroyed and at 62 ° within 30 minutes - 4.
  These bacteria die off much faster than many other non-spore bacteria in frozen, especially acidic foods, where the concentration of acids greatly increases as a result of freezing of water. In butter at a temperature of about —18 ° E. coli has not completely died off for several years.
  Salmonellы. Bacteria of this genus cause gastrointestinal infections of the infectious type. Salmonella enter products with insufficient veterinary and sanitary inspection at the places of processing raw materials and multiply when technological and sanitary conditions are violated (insufficient heat treatment, slow cooling, storage at elevated temperatures, etc.). These bacteria stop multiplying at a temperature of 5 °
Salmonella is heat sensitive. Meat contaminated with salmonella after boiling for an hour 2,5. did not cause human disease [16]. Some types of salmonella are commonly found in waterfowl eggs. Salmonella are also found in chicken eggs obtained from chickens with salmonellosis [17].
   Fyekalinyye stryeptokokki (enterococci). These bacteria can be read as a more reliable food quality indicator than E. coli. They are also constantly contained in the intestines of humans and animals. The greatest practical importance in food microbiology is given to Str. faecalis and str. liquefaciens, which are found in raw and pasteurized milk, milk powder and cheese, frozen vegetables and other products. The effect of these bacteria on the human body has not yet been clarified. Some believe that bacteria cause disease of the body, getting into the gastrointestinal tract; others include these toxigenic bacteria that can cause toxin formation in foods.
  Fecal streptococci are characterized by greater cold resistance compared to Escherichia coli. So, in green beans at a temperature — 17,8; —20, —29 ° fecal streptococci remained almost in their original quantity for more than 400 days [18].
According to the content of streptococci in frozen products more properly assessed the conditions of manufacture and storage of up to refrigerator available.
Fecal streptococci isolated from canned gammon grew in the presence of 40% bile (at pH 9,6) and in the presence of 6,5% NaCl. Their growth temperature range is from 10 to 45 °. They withstand heating at 60 ° for 30 minutes.
  П88 ° When they died within one minute [19].
  Fecal streptococci are resistant to chlortetracycline and to the effects of ionizing radiation (see. Table. 3).
However. This is a non-pore motile bacterium. In response to external environmental influences and temperatures, Proteus is close to the bacteria of the group of Escherichia coli. The growth of protea stops at a temperature of about 5 °. Only individual members can breed at temperatures around 0.°
Proteus has a very active proteolytic ability; in this respect, it is second only to anaerobic spore-forming bacteria. In the Proteus group, pathogenic strains may also occur. The presence of Proteus bacteria is unacceptable in finished meat products (culinary products, boiled sausage, jelly, frozen culinary meat products, etc.).
  Proteus bacteria are resistant to the antibiotic biomycin (chlortetracycline), so this drug is applicable to meat products only at low temperatures or in combination with additional antibiotics.
   Staphylococci. Staphylococcus - spherical nesporenymi bacteria. Bacteria of the Staphylococcus aureus (Staphylococcus aureus) species may contain toxic strains. These bacteria stop multiplying at temperatures around 7 °. In some cases, staphylococcus can cause food poisoning, for example, by consuming ice cream and cream cake, some dairy products (cottage cheese, cheese) and other products, if these products or their component parts are stored at temperatures above 7 °. Staphylococcus can cause pustular diseases if they fall into open wounds or on weak mucous membranes.
Staphylococci are very common in nature.
   Toxigenic staphylococcal strains were found in the nasopharynx more than in 50% of healthy people [20]. Therefore, the possibility of their falling into products is very great.
Staphylococcus dairy products fall into the following cases: when milk is obtained from cows suffering from mastitis; if dairy products are made without prior pasteurization (for example, cottage cheese and cheese) or by smashing (cottage cheese); as a result of milk contamination after pasteurization.
Staphylococci can be contaminated with large batches of dairy products due to the mixing of milk from mastitis cows with milk of all milk yield.
Staphylococcus products can enter through individuals suffering from pustular diseases or carriers of these bacteria. In order to avoid the multiplication of staphylococci and the formation of toxin products should not be stored for a long time above the minimum temperature of reproduction of these bacteria.
Staphylococcus is very resistant to the action of both low and high temperature. They can withstand heating at 100 ° for 35 min. Some strains with dry heat and in a greasy environment withstand longer heating.
To destroy bacteria in creams, it is recommended to warm them up at 90 ° for 20 — 25 min. or at 220 ° for 15 min. [21]. Not only bacteria, but also toxins formed by them are resistant to storage. This explains, for example, cases of poisoning with ice cream or cottage cheese after long-term storage of these products at low temperatures, when the multiplication of these bacteria did not occur. The toxin maintained the temperature of 100 ° (boiling water) to 20 min. and 120 ° in a greasy environment.
Staphylococcal toxin can be detected in culinary products, if the manufacturing process did not follow the cooling or heat treatment.
The presence of staphylococcal toxin does not affect the color of the product and its smell, but is manifested only in the painful symptoms of a person. The presence of the toxin can be determined by the reaction of the kittens to the intravenous administration of the toxin. Determination of toxigenic staphylococci can be done by a complex of indicators and with the help of specific phages [22].
Staphylococci can grow in media with a high content of NaCl (Up to 9%). Therefore, they can multiply in salted foods and environments. To identify the content of staphylococci, 7,5% PaC1 is added to the medium. However, the identification of staphylococci in fish, whose microflora also multiplies with a high salt content, is difficult.
  Sporoobrazwyuşçïe anaerobic. These bacteria can be found in some types of products. If the products are stored in anaerobic and in favorable temperature conditions for the growth of these bacteria before cooling, or are cooled very slowly, toxins can form in them. Such cases, however, are very rare and only under abnormal storage conditions.
If products containing toxins of anaerobic bacteria enter the cold storage, the activity of toxins can be maintained for a long time (over several years).
Spore-forming aerobes. These bacteria stop reproduction at temperatures above 5 °. However, they may, to some extent, have a negative effect on the product even in conditions below the temperature minimum of growth. This action may occur due to the strong collagenase and gelatinase activity in softening the tissue. However, for this action to take place, especially at low temperatures, the content of these bacteria must be very high. Therefore, their value in refrigerated storage is extremely limited.


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