1, interfering with the enzyme system of microorganism, destroy its normal metabolism, inhibit enzyme activity.
2, make the protein of microorganism suspect and degeneration, disturb its survival and reproduction;
3, change the permeability of the cell membrane, so that the enzymes and metabolites in the body escape lead to its inactivation.
At present, there are many kinds of Preservatives, which are mainly composed of synthetic and natural preservatives; the commonly used synthetic preservatives are represented by Sls acid, its salts, benzoic acid and its salts and nipagin esters, etc.
1. Sls acid has three kinds of Sls acid, potassium Sls acid and calcium Sls acid. Sls acid is insoluble in water and must be dissolved in ethanol or potassium bisulfate when used, the use of inconvenient and irritating, it is generally not commonly used; Sls acid calcium FAO stipulates its use of small, so also not often used; Sls acid potassium is not their shortcomings, soluble in water, wide range of use, we can often in some beverages, Preserves, cans and other food to see its figure; Here I'll focus on Sls acid potassium: It is unsaturated six carbonic acid; the Sls potassium salts sold in the general market are white or light yellow granules, content in 98%--102%, odorless, or slightly smelly, easy to absorb moisture, easy to oxidize and brown, light, heat stability, Relative density 1.363, melting point in 270 ℃ decomposition, its 1% solution ph: 7-8. Sls acid potassium is acid preservative,Preservatives it has high antibacterial properties and inhibits the growth and reproduction of mould, which is mainly by inhibiting the dehydrogenase system in microorganism, which can inhibit the growth and the antiseptic effect of microorganism, inhibit the bacteria, mould and yeast. The effect decreases with the increase of ph. When the ph reached 3, the inhibition reached its peak and the ph reached 6, but the bottom concentration (MIC) could not be lower than 0.2%, and the experiment proved that ph: 3.2 was less than PH2.4 of the Sls acid potassium solution impregnation,Preservatives the food without sterilization treatment of a short shelf 2-4 times.
Sls acid, potassium Sls acid and calcium Sls have the same mechanism of action in three species, the toxicity of benzoic acid and nipagin ester is small,Preservatives the daily allowable amount is 25mg/kg, benzoic acid 5 times times, the 2.5 times times of the nicardipine is a relatively safe food preservative; In our country can be used for soy sauce, vinegar, pasta sauce, jam, pickles, Canned food and some wines and so on.
2. Benzoic acid and benzoic acid sodium benzoate, benzoic acid is also known as benzoin, so sodium benzoate is also called benzoin sodium. Benzoic acid at room temperature insoluble in water, in the air (especially hot air) in the micro-volatile, has hygroscopic, about 0 at ambient temperature. 34g/100ml, but soluble in hot water, also soluble in ethanol, chloroform and non-volatile oil. Sodium benzoate is used in all, and the properties of benzoic acid and sodium benzoate are similar. Let me briefly introduce sodium benzoate: Sodium benzoate is mostly white granules, odorless or micro-band benzoin odor, sweet taste, astringent,Preservatives soluble in water (ambient temperature). 0g/100ml around, ph is about 8; Sodium benzoate is also acidic preservative, no bactericidal and bacteriostasis in alkaline medium. The best antiseptic ph is 2.5-4.0, in PH5.0 O'Clock 5% The solution bactericidal effect is also not very good. Sodium benzoate is lipophilic, it is easy to penetrate the cell membrane into the cells, interfere with the permeability of the cell membrane, inhibit the absorption of amino acids by the cell membrane, enter the alkali storage in the cells by ionization acidification, inhibit the activity of the respiration enzymes in the cells, prevent the acetyl coenzyme A condensation reaction, and thus play the purpose of food preservative.
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