Preservatives are divided into two categories: chemical preservatives and natural preservatives. Chemical preservatives are divided into organic preservatives and inorganic preservatives. The former mainly include benzoic acid, sorbic acid, etc. The latter mainly include sulfates and nitrite. Natural preservatives, usually derived from the metabolites of animals, plants and microorganisms, such as lactate streptococcus.
Benzoic acid and its sodium salt is one of the most commonly used preservatives in food processing industry in our country, it is mainly used for beverages and other liquid foods (such as soda, fruit juice, soy sauce, canned, alcohol, etc.) of the corrosion protection. Benzoic acid is also known as benzoic acid, molecular formula C7H6O2. Benzoic acid is a single aromatic carboxylic acid. Benzoic acid is hydrophilic, easy to penetrate cell membrane and into cells, thus interfering with the permeability of microbial cell membrane and inhibiting the absorption of amino acid by cell membrane. Enter the cell in the body of benzoic acid molecule, ionization acidification, alkaline substances in the cell, and inhibit the activity of cellular respiration enzymes, condensation reaction of acetyl coa strong block effect, thus play A role on the corrosion prevention of food. Benzoic acid has a wide antibacterial spectrum in an acidic environment. It has a strong inhibitory effect on bacteria, and is weak in the inhibition of yeast and mould. The optimal pH value of corrosion is 2.5 ~ 4.0. Because benzoic acid is insoluble in water, the practical application of sodium benzoate is often substituted. Sodium benzoate can only function as a preservative when it is free of benzoic acid. In the stronger acid food, sodium benzoate has good antiseptic effect. Benzoic acid and its sodium salt are safe food chemical preservatives, used in the use of food additives, and no toxic side effects have been found.