Common food preservation methods, food is a necessity for human survival, but many foods are very perishable if not preserved properly, so food preservation is particularly important. Share with you some common food preservation methods.
Common food preservation methods 1 1, vacuum box preservation method;
Put the cooked food in the vacuum box, and put it in the microwave oven without vacuum 10 minute. Vacuum immediately after taking it out. Dishes treated in this way can be stored at room temperature for one week without deterioration. Generally speaking, as a seller on Taobao, it is a good solution.
Wet water preservation: two plates, the big one holds water and the small one holds food. Cover them with wet towels and put them into the big plate.
2, food preservatives:
Preservatives can mainly coagulate or denature protein of microorganisms, thus interfering with their growth and reproduction. Preservatives have effects on microbial cell walls and cell membranes. Because it can destroy or damage the cell wall, or interfere with the mechanism of cell wall synthesis, make intracellular substances leak out, or affect the electron transfer system of respiratory chain related to membrane, it has antibacterial effect.
It acts on the structure of genetic material or genetic particles, and then affects the reproduction, transcription and protein translation of genetic material. Enzymes acting on microorganisms will inhibit the activity of enzymes and interfere with their normal metabolism. Thereby having a realistic fresh-keeping effect.
3, adjust the gas composition to keep fresh:
By adjusting the gas composition, inert gas is used instead of oxygen, thus inhibiting the growth of microorganisms.
4, plastic wrap:
Plastic wrap can preserve the moisture of fruits and vegetables and avoid bacterial infection and oxidation of some fruits. It is best not to wash vegetables before preservation, wrap them in plastic wrap or plastic wrap and put them in the refrigerator, because cleaning will destroy the wax on the surface of vegetables and facilitate microbial invasion. Vegetables and fruits are suitable to be put in the supermarket fresh-keeping cabinet with low temperature and high humidity.
5. Refrigeration method of fresh-keeping cabinet:
Constant temperature refrigeration can be set in the fresh-keeping cabinet, which makes the humidity requirement more accurate. Fruits, vegetables and meat can be preserved in the safest way. Moreover, it also has a display function, which is also very helpful for the sales of products.
6, microwave preservation method:
Microwave heating to 72℃ in a short time (120s), and then the processed food is put on the market at 0-4℃, which can be stored for 42-45 days without deterioration. It is very suitable for supplying "seasonal fruits and vegetables" in the off-season and is favored by people.
7, microbial preservation method:
Ethylene can promote the aging and maturity of fruits and vegetables, so in order to keep fruits and vegetables fresh, ethylene must be removed. After screening and research, scientists isolated a kind of "nh-9 strain", which can be made into "ethylene remover nh-t" to remove ethylene, which can prevent grapes from browning, loosening and falling off during storage, and prevent tomatoes and peppers from losing water, changing color and softening, with obvious fresh-keeping effect.
8, air-drying preservation method
Especially in the dry northwest, air drying is often used. After air drying, meat can be preserved for decades at most. For example, ham will keep fresh for a long time after air drying, and the longer the time, the higher the price. Air drying is mainly used for meat. Flowers, fruits and vegetables can also be preserved after air drying. For example, lilies and roses can be preserved for one or two years after air-drying. Air-drying is mainly to remove water from food and store it in ventilation at different temperatures, which has no effect on the preservation of fruits and vegetables.
Common food preservation methods 2 1, low temperature preservation method: low temperature preservation method is a common method to preserve cooked food. Its main principle is to effectively inhibit the growth and reproduction of microorganisms, 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: High-temperature storage method is often used to store food in catering industry, because microorganisms have weak tolerance to high temperature and can effectively kill microorganisms when the temperature rises. Destroy the activity of enzyme. It can prevent the influence of microorganisms on food and achieve the purpose of storing food.
The method is to thoroughly soak or steam the food with boiling water (reaching a high temperature above 100 degrees), and take it out or soak it in the original soup. Keep it in a cool and ventilated place without stirring to prevent food from being contaminated again. This method can keep food from spoiling for a long time. This method is suitable for the preservation of finished and semi-finished products of animal foods, and also for the preservation of dry foods such as water.
3. Ventilation storage method: Ventilation storage method is mainly suitable for storing grain, dry grain and food that needs air drying. Are afraid of mold and cover. For example, rice, noodles, peanuts, vegetables and other foods need ventilation when stored. This can make mold difficult to grow, keep the original ingredients of food and reduce mildew.
4. Vacuum sealing preservation method: vacuum sealing preservation method is to make food not contact with microorganisms in the air under vacuum. A method for sealing and preserving foods, such as canned products and vacuum-packed products. This method is suitable for the preservation of various foods.
Precautions for purchasing food:
1. When buying food, check the production date, shelf life and shelf life of the food. Eating expired and deteriorated food has a high probability of poisoning;
2, check the food packaging, check whether the packaging is in good condition, whether there is air leakage, whether it is cross-contaminated with other foods;
3. Check whether the food packaging bag has the product mark of the quality inspection mark and the QS mark of the quality certification;
4. Check the information on the food packaging bag to confirm whether there is a manufacturer, place of origin and production date;
5. News about food safety. If the news has reported the problematic food brand, you should choose not to buy it.
Common food preservation methods 3 kinds of food preservation methods
First, strawberries rot.
Fresh strawberries bought from the supermarket have been kept in the refrigerator for less than two days, and some parts begin to rot or mold. This is because strawberries have high water content and thin skin, and are easy to be damaged, softened and rotted.
Strawberries are usually soaked in calcium lactate solution to achieve the purpose of preservation. It is difficult to judge which preservatives are sprayed from the appearance, but they are harmless to the human body, but these preservatives are not lasting, and strawberries are facing the fate of rotten heads and rotten tails.
When cleaning strawberries, you can add a few drops of apple vinegar or white vinegar to clear water, gently rub the surface of strawberries to remove most preservatives, which can also keep strawberries stored in the refrigerator fresh and not perishable.
Second, bananas turn black.
Because of its own characteristics, bananas will grow a little "black spots" after being exposed for a few more days, and many people are afraid to eat them.
The epidermal cells of bananas contain an oxidase. It is tightly wrapped by the cell membrane. However, once squeezed or frozen, the cell membrane ruptures and oxidase flows out for oxidation, resulting in a black compound.
As long as banana stems are wrapped with fresh-keeping paper to reduce exposure to air and release ethylene with ripening effect, their fresh-keeping time can be prolonged, and it is more effective to wrap them separately.
Third, tea leaves are affected with damp.
Tea lovers believe there is a lot of tea in the cupboard. Some improperly stored and poorly sealed tea leaves are easy to deteriorate due to moisture and cannot taste the most original fragrance.
Tea has the characteristics of "moisture absorption". Many people expose wet tea in the sun, which will make tea taste bad. The best way is to use a clean pot, stir-fry the tea with slow fire until the steam disappears, and then seal it after cooling, so that the loss of tea fragrance is small.
Fourth, bread is dry and hard.
Bread will go moldy if it is not collected properly. If it is not found, it will be eaten in the stomach, which will easily lead to gastrointestinal revolution.
In addition, a whole piece of bread can't be eaten in three or two days, and it is easy to dry and harden if it is left for a long time. How to solve this problem?
Put a piece or two of celery in the bread package and seal the bag tightly. The moisture contained in it can keep the bread "moist" and fresh at any time, and you can eat soft bread at any time.
Five, meat vacuum packaging
Pork, chicken, salmon and so on. What is taken out of the refrigerator is always hard, frozen and caked, and it takes a long time to thaw.
How to make fresh meat safe and have better meat quality?
First, fill a big container with clean water. Next, put the fresh meat into a sealed bag and close the sealing strip, leaving only a small mouth.
Put the sealed bag into the water, use the water pressure to squeeze out the air in the bag, and completely seal the bag until the sealing strip is close to the water surface, thus achieving the effect of vacuum packaging.
At this time, you can see that there is not much air left in the bag. After wiping the water out of the bag, it can be stored in the refrigerator to keep the food fresh for a long time.
Preservation technology:
Refrigeration and freezing
Refrigeration and freezing are perhaps the most widely used food preservation methods today. The purpose of refrigeration is to slow down the action of bacteria, so that food can be preserved for a long time (it can be kept fresh for a week or two, not just half a day). The purpose of freezing is to stop all bacterial activities, because bacteria will completely lose their activity under freezing conditions.
Refrigeration and freezing are suitable for almost all foods: meat, fruits, vegetables and drinks. Generally speaking, cold storage has no effect on the taste and texture of food. Freezing has no effect on the taste and texture of most meats, and has little effect on vegetables, but it will completely change the texture of fruits (pulp will become mushy). Cold storage is widely used because it has little effect on food.
Canning manufacturing
From about 1825, canning has become a way for people to preserve food for a long time. In the manufacturing process of canned food, the food is boiled in canned food to achieve the sterilization effect, and then sealed (before or when the food is boiled) so that new bacteria cannot enter.
Because the food in the jar has been completely sterilized and will not go bad. Once you open the can, bacteria will enter and attack the food, so you must "refrigerate after opening" (this word is on many food labels-which means that the food inside is sterile before opening the package).
We usually think that "cans" are metal products, but in fact many sealed containers can be used to make cans. For example, glass bottles can be boiled, sterilized and sealed. Soft bags and boxes made of foil or plastic materials are also acceptable. The boxed milk on the shelf is canned milk. The milk in the box is sterilized (instant sterilization at ultra-high temperature) and sealed in the box, so the milk will not go bad even at room temperature.