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The influence of microorganisms and environmental factors on the quality of products


Food products containing 30% water or more are a good breeding ground for microorganisms. During propagation, microorganisms secrete enzymes that decompose proteins (proteolytic), fats (lipolytic), carbohydrates (amylolytic) to intermediate or final decomposition products. At the same time, the properties of the products change for the better or for worse.
The ability of microorganisms to improve the properties of food products is used in the food industry for the preparation of lactic and bakery products, drinks, processed products of vegetables and fruits, herring, kilka and other products.
Microorganisms that improve the properties of products include lactic streptococci, lactic diplococci, lactic acid bacilli: acidophilic, Mechnikovskaya, Bulgarian, yeast, kefir fungus (casein grains with lactic cocci and rods living in them), etc.
Lactic acid bacteria are widely used in the preparation of fermented milk products - kefir, yogurt, acidophilus, cottage cheese, cheeses. Lactic acid bacteria secrete enzymes that decompose lactose to form lactic acid. Composing various combinations of lactic acid bacteria (sourdough), you can get products with different taste properties. The lactic acid contained in these products has the ability to inhibit the growth of putrefactive microorganisms of the human intestine.
Yeast causes alcoholic fermentation, in which carbohydrates decompose to form ethyl alcohol and carbon dioxide. Alcoholic fermentation is used in the preparation of beer, wine, bread dough.
There is a large group of microorganisms, the reproduction of which worsens the properties of the products, they spoil: rot, sour, fermentation. At the same time, food substances, especially protein, decompose with the formation of chemical compounds that give the products an unpleasant, unusual taste, color, smell. Such compounds include skatol, indole, cadaverine, ammonia, hydrogen sulfide, etc. Based on methods for determining the presence of these compounds, the establishment of food quality in food laboratories is based.
The microorganisms causing food spoilage include a large group of putrefactive and other microorganisms that cause acetic acid, butyric acid fermentation, rotting, mold:
B. proteus vulgaris, B. putrificus, E. coli, B. ruosuaneum, Str. thermophilus, B. fluorescens, Cl. sporogenes, molds, some types of yeast, etc. For example, anaerobes are capable of fermenting with butyric acid to form butyric acid, causing damage to cheeses, canned foods, vegetables, and dairy products.
The spoilage of products can also cause enzymes contained in the tissues of the products themselves intended for nutrition.
Pathogenic microorganisms that do not cause signs of spoilage can multiply in food. The use of such products or food prepared from them leads to diseases - food poisoning, intestinal infectious diseases.

The group of pathogenic microorganisms includes bacteria of the genus Salmonella, Shigella, E. coli, Staphylococcus anfrpus, Cl. botulinum, as well as potentially pathogenic microorganisms of the genus Proteus, Cl. perfringens, E. coli, B. cereus, Yiersinia, Vibrio parahaemoliticus, some microscopic fungi, etc.
For growth and reproduction in food, microorganisms require certain conditions, which are called favorable:
ambient air temperature 20–45 ° С; moisture in the product 30% or more; the presence in the product of proteins, carbohydrates and other substances in a well-digestible form; low acidity of the product.
Increased temperature and moisture content, delicate texture of the product contributes to the rapid multiplication of microorganisms.
Many microorganisms release toxins - toxic substances that do not change the taste, smell and appearance of the product. The use of products containing toxins leads to food poisoning.
The reproduction of microorganisms is especially fast, often with the release of toxins in meat, fish, dairy, egg products, cream for confectionery products, sauces, side dishes, salads and vinaigrettes.

To prevent the development of microorganisms, it is necessary to create certain conditions under which the development of microorganisms and the formation of toxins slows down or stops. One of these conditions is the storage of perishable products at low temperatures. Temperature 2-6 ° С (in refrigerated cabinets, counters, chambers) does not cause the death of microorganisms, does not stop, but only slows down their reproduction. In this regard, especially perishable products have a limited shelf life and sales, expressed in hours. The period of storage and sale is the period from the end of the technological process of preparing a product or food to their use.
Particularly perishable products intended for long-term storage are placed in low-temperature refrigerating chambers at a temperature of -25-30 ° С, where the development of most microorganisms stops. However, there is a group of microorganisms that are resistant to subzero temperatures (especially in conditions of high humidity), which can develop at -10 ° C, so frozen foods can become moldy and become poor-quality.
Not only especially perishable products (milk, jam, sausage, cream products, etc.), but also food prepared from them should be safe in epidemiological terms.
The conditions ensuring the safety of the quality of prepared (hot) food in public catering establishments are its storage for no more than three hours at a temperature of 65–75 ° С, at which microorganisms do not multiply.
If stored and transported incorrectly, foodstuffs may be exposed to oxygen, light, temperature, and moisture. Mechanical impurities can get into food.
Under the influence of atmospheric oxygen, light and elevated temperature, edible fat and fat-containing products are oxidized with a decrease in the nutritional and biological value of fats. These products accumulate aldehydes, ketones, free acids and other compounds that are not indifferent to the body and cause a deterioration in the organoleptic properties of fat - the appearance of an acidic, rancid taste and unpleasant odor; the color of fat at different stages of spoilage becomes intensely yellow, green, white.
Many foods have the ability to absorb moisture (hygroscopicity of the product). These include dried fruits, concentrates, flour, cereals, sugar, etc. Storage or transportation in conditions of high humidity helps to reduce the nutritional value of the product, since the moisture content increases per unit mass of the product. Excessive moisture in the product contributes to the development of mold, reproduction of insect pests, activation of tissue respiration in vegetables and fruits. Excessive air dryness in warehouses is undesirable - the products dry out, their mass decreases, their appearance worsens, their shape and taste change.
The quality of the products or food prepared from them is sharply reduced until it is impossible to eat when sand, earth, glass, chips from enameled dishes and other impurities are ingested. This can happen during repairs with simultaneous operation of the facility, improper transportation, storage or processing of products. An admixture of sand and earth is epidemiologically dangerous, because with visible foreign particles microorganisms and helminth eggs get into food.
The prevention of food poisoning and intestinal infectious diseases transmitted through food products, monitoring compliance with sanitary rules for the receipt, storage, transportation, processing and sale of food and products is an important section of the work of the medical assistant in protecting the health of the population of our country.
To preserve the good quality, nutritional and biological value of the products for a long time, canning is used.
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The influence of microorganisms and environmental factors on the quality of products

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