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1. Low temperature preservation: It can inhibit the reproduction of microorganisms and slow down the spoilage rate of food, but it cannot completely kill microorganisms. 2. High temperature sterilization
Food is processed at high temperatures to kill most bacteria and enzymes. Combined with sealed, vacuum, and rapid cooling treatment, it can effectively delay food spoilage. 3. Dehydration and drying
That is, if the moisture of the food is reduced below a certain limit, microorganisms will not be easy to grow and reproduce, and the activity of enzymes will be suppressed and compromised. <
1. Low temperature preservation: It can inhibit the reproduction of microorganisms and slow down the spoilage rate of food, but it cannot completely kill microorganisms. When storing at low temperatures, it is necessary to pay attention to the control of temperature, generally speaking, the lower the temperature, the longer the storage time.
2. High temperature sterilization: After high temperature treatment, food can kill most of the bacteria and enzymes. If combined with airtight, vacuum, and rapid cooling treatment, it can effectively delay the spoilage of food and prolong the shelf life, such as the bagged pure milk, pasteurized milk, beer and so on.
3. Dehydration and drying: that is, if the moisture of the food is reduced to a certain limit, microorganisms will not be easy to grow and reproduce, and the activity of enzymes will be inhibited. Common dehydration methods used in households are sun exposure, shade drying, heating and evaporation, or freezing drying.
Although the sun method is simple, the loss of vitamins is large.
4. Increase osmotic pressure: such as salting or sugaring. When the concentration of salt is 8 10, it can inhibit the reproduction of most microorganisms, but it cannot completely kill it.
To kill microorganisms, the concentration of salt should be 15 20; The sugar concentration of candied food should be 60 65 to inhibit the reproduction of microorganisms. Attention should be paid to sealing and moisture-proof when storing. Common candied foods include preserved fruits, preserves and jams.
5. Increase the concentration of hydrogen ions: Most bacteria cannot grow and multiply normally in the following, so they can be preserved by using the method of shielding to increase the concentration of hydrogen ions. Vinegar is the addition of vinegar to food, such as common vinegar and sour fermentation, which are commonly used in vegetables and fruits, such as pickled cucumbers, sauerkraut, etc.
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Here's how to store food:
1. Low temperature storage. Cryopreservation can inhibit the reproduction of organisms and slow down the rate of food spoilage, but it cannot completely kill microorganisms. When storing at low temperatures, it is important to pay attention to temperature control, generally speaking, the lower the temperature, the longer the storage time.
2. High temperature sterilizationFood is processed at high temperatures to kill most bacteria and enzymes. If it is treated with airtight, vacuum and rapid cooling, it can effectively delay the spoilage of food and prolong the storage time.
3. Dehydration and dryingDehydration and drying is to reduce the moisture in the food below a certain limit, so that microorganisms are not easy to grow and reproduce, and the activity of enzymes will be inhibited. Common methods of dehydration in the home are sun drying, shade drying, heating evaporation, or freeze drying, among others.
4. Increase osmotic pressure. The name may seem difficult to understand, but most people have used it before. For example, marinating food with salt or sugar. When the concentration of salt is 8%-1%, it can inhibit the reproduction of most microorganisms.
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1. Refrigeration method. Low temperature can slow down the process of chemical reactions in food, reduce the activity of enzymes, and inhibit the reproduction of microorganisms, so food can be stored for a longer time when it is stored in the refrigerator or in a natural friend environment that freezes outside in winter. If food is kept in a cooler environment, as is often said, it will last less than if it is frozen.
2. Sealing method. Fill the food into a container, cover or seal the container to isolate the food from the air, and this method can be used to store cooking oil or grain.
3. Drying method. That is, the dehydration method, which is sun-dried, fire-roasted, smoked or air-dried to remove moisture from food and prevent food from spoiling and rotting. Such as drying dried vegetables or meat products.
4. Boiling method. Sterilize food in boiling water and then dry it for preservation, such as some meats or certain vegetables.
5. Salting method. Salting food after washing it can preserve food for a considerable period of time, which can control the growth of bacteria and prevent contamination.
6. Sugaring method. Similar to the salt-carrying dust staining method, the food can be preserved for a long period of time because the change of osmotic pressure makes the microorganisms indisputably capable of multiplying.
7. Burial method. Burying food in the ground and sand, charcoal lime, lime can reduce the loss of food moisture, avoid air pollution, and is more suitable for preserving tuber vegetables, eggs, etc.
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1. Low temperature storage method. The cryogenic storage method is a commonly used method for storing cooked food grades. Its main principle is to effectively inhibit the growth and reproduction of microorganisms through low temperature, reduce the activity of enzymes, weaken the chemical reaction in food, and better maintain the original flavor and nutritional value of food.
2. High temperature storage method. The high-temperature storage method is a method that is often used in the catering industry to store food, because microorganisms have a weak ability to withstand high temperatures, and when the temperature is raised, it can effectively kill microorganisms. and destroy the activity of the enzyme.
It can prevent the influence of microorganisms on food and achieve the purpose of storing food.
3. Ventilation storage method. The ventilated storage method is mainly suitable for preserving grains, dry foods, and foods that need to be air-dried. They are characterized by fear of mildew and covering.
For example, rice, noodles, peanuts, vegetables and other foods need to be ventilated when they are stored. This makes it less likely for mold to grow, retains the original composition of the food, and reduces mold.
4. Pickling, pickling, sauce and soaking storage methods. This method is generally to use salt, sugar, vinegar, sauce and five spices, according to a certain proportion of square spike coarse method to add human food, so that the food absorbs a certain concentration. to inhibit the growth of microorganisms.
Achieve the purpose of long-term preservation of food. For example, pickled vegetable products include salted radish strips, salted beans, sweet and sour garlic, etc.
5. Smoked storage method. Smoking is a method of using saws, pine shoots and other materials, in the case of incomplete combustion of the smoke produced by the smoke to smoke food, the smoked food not only reduces the moisture inside the food, and the smoke has sterilization and antiseptic effect of wood tar, creosote and so on attached to the surface of the food. It can prevent the growth of bacteria, so as to achieve the role of preservative storage, and the common smoked products are smoked fish, smoked chicken, smoked meat, etc.
6. Vacuum-sealed storage method. Vacuum-sealed storage methods keep food in a vacuum and do not come into contact with microorganisms in the air. A method of sealing and preserving food, such as canned products, vacuum-packed products, etc.
This method is suitable for the preservation of a variety of foods. With the continuous development of science and technology, there are more and more ways to store food, such as nuclear radiation storage method, modified atmosphere method, etc., which are more advanced methods, their main principle is to control or kill the microorganisms growing in the food, delay the metabolism of the internal tissues of raw materials, so as to prolong the preservation time of food, improve the quality of storage, and achieve the purpose of preservation.
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