What is the basic principle of food preservation in living things?

Learn about food preservation, and know what factors cause food to spoil.

Food deterioration is mainly due to microorganisms, chemical reactions, and physical factors

1.Microbe.

Microbes are everywhere in the environment we live in. Microorganisms can use the energy and nutrients provided by food to grow and multiply, causing things to spoil (some microorganisms are also used in food processing).Factors that control the proliferation of microorganisms include temperature, activity of water molecules, oxygen, major components of food, etc.

Controlling these factors can effectively reduce food spoilage caused by microorganisms.

2.Chemistry. It is mainly caused by oxidation reactions.

Fat oxidation produces free radicals that are harmful to the human body, and can also cause odors in fats. Oxidative reactions can discolor leafy greens and also destroy their nutrients. High temperatures, high oxygen, sunlight, ultraviolet rays, etc., will all exacerbate the oxidation reaction.

3.Physics. Due to the effects of transportation, the process of storage on certain textures of food. Such as potato chips, strawberries, etc.

One of the most influential microorganisms is the impact on food. Therefore, many methods of preserving food have been developed in the food processing industry. Common ones are refrigerated, frozen, high-temperature sterilized, ultra-high temperature sterilized, preservatives, dried, sealed packaging, etc.

The technologies that have emerged in close proximity include ultraviolet sterilization, microwave sterilization, high-pressure sterilization, nanotechnology, etc.

The main way to prevent oxidation in food is to add antioxidants to food.

1) Physical Preservation Law.

It is mainly used to control temperature, humidity and vacuum.

and other physical factors to achieve the purpose of effective preservation of food.

Dehydration and drying preservation method most microorganisms need to be in water content.

More than the food in order to grow and multiply.

If the moisture content in the food drops to below, these microorganisms will not survive. So the food industry is often.

It is convenient to use natural drying (sun-drying, shade-drying) or artificial mechanical drying to produce dried fruits, dried vegetables, fish floss, meat floss, etc.

Preserved food.

The physiological and biochemical reactions of microorganisms in food under refrigeration and frozen preservation methods are effectively inhibited at low temperatures, and the food can be stored for a long time without spoilage. The biggest advantage of cryogenic food is that the raw materials can be retained very satisfactorily.

or the freshness, flavor and nutritional content of the product, with a long shelf life.

The food canning method uses variable temperature sterilization, and then canning vacuuming, sealing sterilization, and cooling. This is the purpose.

It is the most widely used, the most varied, the most safe and reliable, easy to eat, and the food with intact flavor in the former physical preservation.

Depository. The food radiation preservation method uses the extremely strong penetration of the rays produced to remove fresh meat and its ...

Products, aquatic products and their products, fruit and vegetable products, etc., are sterilized as a whole under the radiation device, and the hair is inhibited.

Treatments such as budding, delayed ripening, etc., to minimize the loss of food. The quality and flavor of the processed food are not.

Raw and cooked are separated, hot and cold are separated, meat and vegetables are separated, boiled and sterilized at high temperature, fresh is stored at a constant temperature of 0--5, and stored and frozen for a long time.

1. Drying and dehydration.

This preservation method is to prevent mold by removing water from the food. The purpose of fermentation bacteria and bacteria growth. For example, fruits can be dried in the sun for the purpose of preservation. Now, a variety of equipment can be used to properly dry food by controlling the temperature of the air.

2. Quick freeze drying.

This is a dehydration process and the food does not need to be preserved or refrigerated. When food absorbs water, it returns to its original state and taste. This method can be used for the preservation of a variety of food products.

Freezing food in a freezer, extracting the air from the cabinet and vaporizing the ice is called freeze drying.

3. Cooling and freezing.

Refrigeration is a method of preserving food, but it does not kill microorganisms, only inhibits their reproduction. The lower the refrigeration temperature, the longer the food will be preserved. The temperature of the refrigerator is generally controlled between 1 and 7 degrees, which can prevent food from rotting in a short time.

Food products must be stored in a deep-frozen manner before use. Most frozen foods can be shelved for one year at 17 degrees and 2 years at 28 degrees.

4. Quick freezing. Quick freezing is to put the food in a shallow box, put it on the hollow shelf, squeeze it through the low-temperature refrigeration restaurant, and stay in the freezing room for 60 to 90 minutes according to the size of the food to achieve food freezing. The spray freezer, also known as low-temperature cold junction, uses liquid nitrogen or carbon dioxide and is a method of freezing food at very low temperatures, which freezes faster than any method.

5. Cool cooked food.

The food is cooked according to the standard cooking method, and then placed in an air cooler to reduce the temperature of the food to 3 degrees, and stored in the refrigerator at this temperature. When taking out cooked food from cold storage, it only needs to use a specially designed plated stove for 12 to 20 minutes to make the temperature meet the requirements for use.

Cryogenic storage method: its main principle is to effectively inhibit the growth and reproduction of microorganisms through low temperature, reduce the activity of enzymes, and weaken the chemical reaction in food. High temperature storage method:

The principle is that microorganisms have a weak ability to withstand high temperatures, and when the temperature is raised, they can effectively kill microorganisms. The ventilated storage method is mainly suitable for preserving grains, dry foods, and foods that need to be air-dried. The principle is to accelerate air circulation.

It can make mold not easy to grow, maintain the original composition of food, and reduce mold. <

1. Low temperature storage method: It is a common method for storing and cooking food. 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: It is a method often used in the catering industry to store food, and its principle is that microorganisms have a weak ability to withstand high temperatures, and when the temperature is raised, it can effectively kill the microorganisms of Acorn. This method is suitable for the preservation of finished and semi-finished animal foods, as well as foods such as dried foods.

3. The ventilation storage method is mainly suitable for preserving grain, dry food and food that needs to be dried. The principle is to accelerate air circulation. Ventilation is required during storage, which can make mold less likely to grow, maintain the original composition of food, and reduce mold.

4. Vacuum sealing preservation method: its principle is to make the food in a vacuum state, not in contact with the microorganisms in the air. A method of sealing and preserving food, such as canned products, vacuum-packed products, etc.

The principle of preservation of food and air companions is as follows:

1) Physical Preservation Law.

It is mainly used to control temperature, humidity and vacuum.

and other physical factors to achieve the purpose of effective preservation of food.

2) Chemical Preservation Method The chemical preservation method is the use of various chemical substances recognized by law to preserve food. Such as sugar, salt, wine,

Vinegar, plant fungicides, preservatives.

and so added to food to inhibit or kill microorganisms to achieve the purpose of preserving food.

3) Biochemical preservation method uses the biochemical changes produced during the reproduction of certain beneficial microorganisms to preserve food. Fruits and vegetables contain sugar.

class, especially bee candy.

Under the action of various microorganisms, fermentation forms a preservable product.

4) Preservation of cooked food ——1373 Chapter 4 Canteen Hygiene Supervision and Management Preservation of Canned Food: Canned food is packed into a special container, vacuumed and sealed, and subjected to high temperature.

Kill the old bacteria, kill the vast majority of microorganisms, so as to preserve food for a long time.