What are the preservative measures What are the commonly used preservative methods for food?

Four. Drying: that is, the water in the perishable items is removed, and the active substances (such as enzymes, etc.) and microorganisms in the items stop moving, and the items will not rot.

Pickling: Perishable items are infiltrated in solid or liquid form with salt or other substances to keep the item at a high osmotic pressure.

state, let microorganisms and enzymes and other inactivation, the item will not rot.

Freezing: A liquid environment is required for the action of enzymes and for microorganisms to grow and reproduce. At extremely low temperatures, liquids solidify, and both enzymes and microorganisms are temporarily or permanently inactivated.

Chemical preservative: use chemical substances (such as formaldehyde, etc.) to treat perishable materials, inactivate the bioactive substances in them, and kill the microorganisms in them, so as to achieve the purpose of antiseptic.

Radioactive irradiation: with radioisotopes.

For example, CO60) irradiates perishable items, and uses high-energy atomic rays to destroy the bioactive substances in the articles and kill the microorganisms in them, so as to achieve the purpose of antiseptic.

1. The most used is anticorrosive paint, but the bottom, middle and top coat requirements should be made according to your process environment.

2. Pipes and equipment made of anti-corrosion materials can be selected, such as steel-lined PTFE, steel-lined PO, rubber, FRP pipes, plastic pipes such as UPVC and PE, and graphite equipment.

3. The metal pipe can also be wrapped with an epoxy resin brush with a glass cloth externally. The number of layers of the glass cloth bag is determined according to the process environment.

4. Connect with specific metal blocks and metal pipes, and use the principle of positive and negative ions for anti-corrosion, that is, cathodic anti-corrosion, but this should be based on your process environment to consult a professional unit in this area, which can be found on the Internet.

5. If you need to pre-corrosive the pool, use epoxy resin and anti-corrosive tiles or anti-corrosive cement (anti-corrosive cement is suitable for concentrated acids with less moisture).

6. In fact, the most important thing is that we must always pay close attention to the on-site running and dripping, and indiscriminately shooting acid and alkaline gas liquid.

Preservative can be used in low temperature refrigeration, usually can be used in the refrigerator, freezer to store food, for some can not be finished can be placed in the refrigerator, is the food in a low temperature state, can achieve the effect of preservative. It can also be sealed in cans, which can prevent the food from rotting and keep the food in a vacuum to prevent the air from being exposed to other bacteria.

There are two ways to prevent wood corrosion, one is to paint the wood grain paint that forms a film, which has the advantage of hard and bright surface, and is not easy to repair after damage; One is the wood wax oil that cannot be coated with a film, which has the advantage of reflecting the grain of the wood itself and is easy to repair, and the disadvantage is that the surface lacks luster.

Alloy steels are one of the most effective methods of corrosion protection, combining the properties of various metals to provide greater strength and resistance to the final product. For example, combining corrosion-resistant nickel with oxidation-resistant chromium can be used to create alloys that can be used in oxidizing and reducing chemical environments. Different alloys provide resistance to different conditions, giving companies greater flexibility.

Anti-corrosion is to protect metal objects that are easy to rust by various means to achieve the purpose of prolonging their service life, usually using chemical anti-corrosion, physical anti-corrosion, electrochemical anti-corrosion and other methods.

The methods and measures of antiseptic are: vacuum packaging, frozen storage, salted storage, air-dried storage, ......

What kind of anti-corrosion is this? If it is engineering, there can be epoxy resin, asphalt paint, anti-corrosion membrane and so on.

Anti-corrosion measures are generally considered from the following aspects according to the principle of corrosion and the structure of the structure:

1) Reasonable selection of materials. Reasonable selection of various metal or non-metallic materials according to the use environment;

2) Electrochemical protection technology, including cathodic protection and anodic protection and stray current discharge technology;

3) Surface treatment technology, such as phosphating, oxidation, passivation, surface conversion film technology, etc.;

4) Coating and coating technology, mainly including coatings, greases, coatings, linings, cladding, etc.'5) Environmental regulation, that is, improving environmental media conditions, such as the use of corrosion inhibitors in closed circulation bodies, adjusting pH value, degassing, deoxygenation, sterilization, desalination, etc.;

6) Correct design and construction, correct material selection and coordination from engineering and product design, reasonable geometric shape and surface state, strict construction technology, and correct protective measures, especially to prevent contact corrosion, stress corrosion, crevice corrosion and weld corrosion.

Generally speaking, there are only these types of anti-corrosion measures, but how to choose the appropriate anti-corrosion measures also needs to be judged according to the specific situation.

1. Vacuum preservation method: burial.

It is an effective method of using vacuum technology to preserve food, and it is now widely used to preserve inanimate food. It is particularly effective for those foods that are easy to change in color and flavor and require crispness, such as potato chips and banana chips on the market. It also has the effect of reducing consumption, delaying maturity, prolonging life, and inhibiting pests and diseases for living foods such as fruits and vegetables.

The vacuum preservation method has particularly high requirements for the pressure resistance of container materials, strict requirements for technology, large investment and high cost, so it cannot be widely used in large-scale production at present. However, one thing is certain, some noble medicinal materials, foods, raw materials, etc., which are small in size, are the objects of vacuum preservation in the first place.

2. Preservative:

It's a preservative. Food preservatives are food additives that can prevent spoilage caused by microorganisms and prolong the shelf life of food. Because it also has the effect of preventing the multiplication of microorganisms and causing food poisoning, it is also known as antimicrobial agent, which can inhibit the spoilage effect that is most likely to occur under different circumstances, especially when the general sterilization effect is not sufficient, it still has a sustained effect.

Mineral oil, coal tar, and denim for the preservative of fibers and wood, and formaldehyde, mercury, toluene, butylparaben, nitrofurfurhydrazone derivatives or balsam resins for biological specimens. The use of preservatives in food is restricted, so it relies on some physical methods such as drying and pickling. Special preservatives include organic acids such as acetic acid, vegetable oils with oleic acid as components, and special essential oil components such as mustard seeds.

3. Modified atmosphere preservation

In fact, it is similar to the essential principle of vacuum preservation, except that modified atmosphere preservation is to inhibit the growth of microorganisms by adjusting the composition of gas Pitcher's and replacing oxygen with inert gas.

1.Vacuum preservation method: As the name suggests, vacuum preservation method is to use vacuum technology to vacuum preserve inanimate ingredients that need to be preserved.

Of course, this technology can also protect living foods such as fruits and vegetables by reducing consumption, delaying ripening, and suppressing pests and diseases.

2.Modified atmosphere preservation method: The modified atmosphere preservation method is also one of the most widely used food blind guess Vipin preservation methods, which mainly uses the way to adjust the proportion of gas in the package to reduce water evaporation and inhibit the growth of microorganisms to achieve the purpose of food preservation.

3.Food preservative preservation method: food preservatives use chemical substances such as benzaldehyde, sodium benzoate, sorbic acid grinding and culture to coagulate or denature microbial proteins, destroy the cell wall or cell membrane of microorganisms, and inhibit the enzyme activity of organisms to achieve the purpose of preservation.

First, glass bottles (use second-hand old godmother-like bottles, pay attention to keep the lid).

Second, heat the homemade sauce to 90 to 100 degrees Celsius, put it in a glass bottle with a kernel bridge, and screw the cap.

Third, use a pot, add water, then heat it, and put it into the bottle where the sauce was just filled. Heat until the water boils, with a number of Paul's for 40 minutes, the latter longer. This is called water bath sterilization.

Theoretically, those sauces should be more than 10% salt at 4 percent, or vinegar, sterilized, and then refrigerated for one to three months or more!

Preservatives can be natural, and many of our daily foods have a preservative effect, such as garlic, bitter melon, some spices and so on.

The commonly used preservative methods of food can be stored in vacuum, frozen, refrigerated, and dried in the water. To the lack of preservatives and the like, it is recommended not to use it.

1. Conventional mildew prevention: (1) low temperature mildew prevention method; Control and regulate the temperature of the warehouse, so that the temperature of the material is below the maximum temperature limit for the growth and reproduction of mold and rot microorganisms, and inhibit the growth of mold and rot microorganisms. (2) Dry and mildew-proof; Reduce the humidity in the warehouse environment and the moisture of the material itself, so that the mold rot microorganisms can not get the water needed for growth and reproduction, so as to achieve the purpose of mildew prevention.

2. The agent is mildew-proof. Antifungal agents can directly interfere with the growth and reproduction of mold rot microorganisms, and the ideal antifungal agents should have good sterilization effect and low toxicity to the human body. Commonly used antifungal agents are aniline salicylate, sodium pentachlorophenol, sodium fluoride, carbendazim, and clean and extinguished.

3. Meteorological mildew prevention. Meteorological mildew prevention is a more advanced mildew prevention method, which has less pollution to materials. It uses the gas emitted by the vapor phase anti-mold agent to inhibit or kill the mold microorganisms on the anti-virus materials to achieve the purpose of mildew prevention.

For example, paraformaldehyde releases formaldehyde gas, which has the effect of coagulation of proteins in moldy microorganisms; Ethylene oxide can release colorless ethylene oxide gas, which can bind to proteins in the body of mold and rot microorganisms, so that mold and rot microorganisms die due to metabolic dysfunction. In addition, physical anti-mildew methods such as radiation anti-mildew and high-frequency anti-mildew can also be used.

1. Improve the essence of metals

According to the different uses of the year, choose different materials to form corrosion-resistant alloys, or add alloying elements to the metal to improve its corrosion resistance, which can prevent or slow down the corrosion of the metal. For example, adding nickel to steel to make stainless steel can enhance the ability to resist corrosion.

2. Form a protective layer

It is an effective way to prevent metal corrosion by covering the surface of the metal with various protective layers to separate the gas corrosive properties of the protected metal. There are two types of protective layers used in industrial kiln auxiliaries: non-metallic protective layers and metal protective layers.

3. Electrochemical protection:

Electrochemical protection is one of the important methods of metal corrosion protection, and its principle is to use external current to change the potential of the corroded metal to slow down or inhibit metal corrosion. Electrochemical protection can be divided into two methods: anodic protection and cathodic protection.

4。Corrosion inhibitor method:

The corrosion inhibitor method is a commonly used anti-corrosion measure, adding a small amount of corrosion inhibitor in a corrosive environment can have a physical and chemical reaction with the metal surface, thereby significantly reducing the corrosion of metal materials.