​Principle
The anti-corrosion principles of preservatives are roughly as follows:

1. It interferes with the enzyme system of microorganisms, destroys its normal metabolism and inhibits its activity.

Second, it coagulates and denatures the protein of microorganisms and interferes with their survival and reproduction.

Third, it changes the permeability of the cell plasma membrane, inhibits the elimination of enzymes and metabolites in the body, and causes its inactivation.

Use standard
When it comes to preservatives, people often think that they are harmful, but in fact, within the scope of safe use, they have no toxic side effects to the human body. There are strict regulations on the use of preservatives in my country, and the preservatives should meet the following standards:

So far, my country has approved 32 kinds of food preservatives, among which sodium benzoate and potassium sorbate are the most commonly used. The toxicity of sodium benzoate is stronger than potassium sorbate, and its antibacterial effect is only 1/3 of sorbic acid under the same acidity value, so many countries gradually use potassium sorbate. However, due to the low price of sodium benzoate, it is still widely used in my country, mainly used in carbonated beverages and fruit juice beverages. Potassium sorbate has strong antibacterial power and low toxicity. It can participate in the normal metabolism of the human body and be converted into CO2 and water. From the perspective of the development trend of preservatives, biological preservatives made from biological fermentation will become the future development trend.
Briefly introduce the product performance, anti-corrosion mechanism and scope of use of commonly used preservatives in my country.

1. Benzoic acid and its salts, white particles or crystalline powder, odorless or slightly benzoin smell. The best anti-corrosion PH is 2.5-4.0, and the sterilization effect is not very satisfactory in the products with PH 5.0 or higher. Because its safety is only equivalent to 1/40 of potassium sorbate, Japan has completely banned its use in food.

2. Sorbic acid and its salts, white crystalline powder or slightly yellow crystalline powder or scaly. Potassium sorbate is an acidic preservative, which has high antibacterial properties and inhibits the growth and reproduction of molds. It mainly inhibits the dehydrogenase system in the microorganisms, thereby inhibiting microorganisms and playing an antiseptic effect. It has inhibitory effect on bacteria, molds and yeasts. The antiseptic effect is significantly higher than that of benzoic acid, 5-10 times that of benzoate. The product has low toxicity, equivalent to half of table salt. The anti-corrosion effect decreases with the increase of PH, and the best anti-corrosion effect is when PH=3. There is still antibacterial ability when the pH value reaches 6, but the minimum concentration cannot be lower than 0.2%. It is less toxic than paraben. In our country, it can be used in soy sauce, vinegar, noodle sauce, beverages, jams, etc.

3. Dehydroacetic acid and sodium salt. Dehydroacetic acid and its sodium salt are white or light yellow crystalline powder, stable to light and heat, degraded into acetic acid in aqueous solution, and non-toxic to humans. It is a broad-spectrum preservative, which has a strong inhibitory effect on bacteria, molds and yeasts in food. It is widely used in the preservation of meat, fish, vegetables, fruits, beverages, cakes, etc.

4. Paraben esters (i.e. parabens), products include methyl, ethyl, propyl, and butyl parabens. Among them, butyl p-hydroxybenzoate has the best anti-corrosion effect. my country mainly uses ethyl and propyl p-hydroxybenzoate. The most used in Japan is
preservative
preservative
Butyl hydroxybenzoate. The antiseptic mechanism of paraben esters is: destroying the cell membrane of microorganisms, denaturing the protein in the cell, and inhibiting the activity of the cell's respiratory enzyme system. The antibacterial active ingredients of parabens mainly act in a molecular state. Because the hydroxyl group in the molecule has been esterified and no longer ionized, 60% of the molecules still exist when the PH value is 8. Therefore, the parabens have good effects in the range of PH4-8. Does not change with the change of PH value, stable performance and lower toxicity than benzoic acid. It is a broad-spectrum preservative. As paraben esters are difficult to dissolve in water, they should be dissolved in ethanol before use. In order to better play the role of preservative, it is best to mix two or more of these esters. Ethyl p-hydroxybenzoate is generally used in fruit drinks, and propyl p-hydroxybenzoate is generally used in fruit drinks.

5. Sodium diacetate is a kind of preservative commonly used in pickles. It is safe, non-toxic and has a good antiseptic effect. The final decomposition products in the human body are water and carbon dioxide. It has obvious inhibitory effect on Rhizopus nigra, Aspergillus flavus, Listeria monocytogenes, etc. In the pickles, 0.2% sodium diacetate and 0.1% potassium sorbate are used in the pickle products, which has a good fresh-keeping effect.

6. Calcium propionate, white crystalline particles or powder, odorless or slightly odor of propionic acid, stable to light and heat, and easily soluble in water. Propionic acid is the product of the oxidation of amino acids and fatty acids in the human body, so calcium propionate is a very safe preservative. ADI (the allowable daily intake per kilogram of the human body) is not restricted. It has an inhibitory effect on molds. Bacterial inhibition is small and has no effect on yeast. It is often used in the fermentation of pasta products and the anti-mold of cheese products.

7. Sodium lactate, the product is a colorless or slightly yellow transparent liquid, no peculiar smell, slightly salty and bitter taste, miscible in water, ethanol, and glycerin. The general concentration is 60%-80%, and the maximum use limit of 60% concentration is 30g/KG. Sodium lactate is a new type of antiseptic and fresh-keeping agent, mainly used in meat and poultry products, and has a strong inhibitory effect on meat food bacteria . Such as Escherichia coli, Clostridium botulinum, Listeria, etc. Through the inhibition of food pathogenic bacteria, thereby enhancing food safety. Enhance and improve the flavor of meat and extend shelf life. Sodium lactate has good dispersibility in the raw meat and good absorption of water, so as to effectively prevent the raw meat from dehydration and achieve freshness and moisture retention. It is mainly suitable for barbecue, ham, sausage, chicken, duck and poultry products and sauce products. The reference formula for keeping fresh in meat products: sodium lactate: 2%, sodium dehydroacetate 0.2%.

8. Biological food preservatives. The production of biological preservatives in my country started with nisin and has a history of ten years. Certain progress has been made in the research, production and application of biological preservatives. GB2760 stipulates that nisin and natamycin can be used. Since 2006, polylysine has been developed (now provided by four companies). The application for polylysine to enter GB2760 is underway. I believe it will not be long. Will be put on the market. In addition, there are products that claim to be biological preservatives, but are actually compound preparations on the market.