Acesulfame is a kind of food additive, a chemical, similar to saccharin, which increases the sweetness of food, has no nutrition and is harmful to human body. Although it is allowed by the state, it must not be used beyond the standard.

The chemical name of acesulfame K is: potassium salt of 6-method 1, 2,3-oxathiazin-4 (3h)-one-2.2-dioxide (6 monomethyl1,2,3-oxazine-2,2-dioxygen potassium salt). Molecular weight: 201.24; English name: Acesulfame-K or Acesulfame Potassium. Also known as potassium sulfacetate, A-K sugar, and Alphonse potassium, 1983 was first approved in Britain, and its sweetness was 200 times that of sucrose. Acesulfame K is stable to light and heat (high temperature of 225℃) and has a wide range of pH values (pH 2-3-7). It is one of the most stable sweeteners in the world at present, and is suitable for baked goods and acidic drinks. In addition, acesulfame K has high safety, pure and strong sweetness and long sweetness duration, and it has obvious synergistic effect when combined with aspartame L: L. Acesulfame K is considered as one of the most promising sweeteners because of its uncomplicated production process, low price and superior performance to aspartame. 1 992, China approved that acesulfame can be used in beverages, ice cream, cakes, preserves, table sweeteners, etc.

Acesulfame K is not absorbed by human body and does not participate in human metabolism.

There are three kinds of antiseptic principles:

1, interfere with the enzyme system of microorganisms, destroy their normal metabolism and inhibit the activity of enzymes.

2, make the protein of microorganism question the solidification and denaturation, and interfere with its survival and reproduction;

3. Change the permeability of cell plasma membrane, so that the enzymes and metabolites in the cell can escape, which leads to its inactivation.

At present, there are many kinds of food preservatives, mainly divided into synthetic and natural preservatives; Commonly used synthetic preservatives are represented by sorbic acid and its salts, benzoic acid and its salts, nipagin esters, etc. I will briefly introduce the characteristics of their doors:

1, sorbic acid includes sorbic acid, potassium sorbate and calcium sorbate. Sorbic acid is insoluble in water, so it must be dissolved in ethanol or potassium bisulfate before use, which is inconvenient and irritating when used, so it is generally not used; Calcium sorbate is not often used because of its small scope of use as stipulated by FAO/WHO. Potassium sorbate does not have their shortcomings. It is soluble in water and widely used. We can often see it in some drinks, preserved fruits, canned foods and so on. Here I focus on potassium sorbate: it is unsaturated hexacarbonic acid; Potassium sorbate sold in the general market is white or light yellow particles, with a content of 98%-102%; It is odorless or slightly odorous, easy to absorb moisture, easy to oxidize and turn brown, stable to light and heat, with a relative density of 1.363 and a melting point of decomposition at 270℃. The pH of its 1% solution is 7-8. Potassium sorbate is an acidic preservative, which has high antibacterial performance and inhibits the growth and reproduction of mold. It mainly inhibits the growth of microorganisms and plays an antiseptic role by inhibiting the dehydrogenase system in microorganisms, and has inhibitory effects on bacteria, molds and yeasts; Its effect weakens with the increase of PH, and its bacteriostatic ability reaches the peak when PH reaches 3, and it still has bacteriostatic ability when PH reaches 6, but the minimum concentration (MIC) cannot be lower than 0.2%. Experiments show that the shelf life of food soaked in potassium sorbate solution with PH：3.2 is 2-4 times shorter than that without sterilization.

Sorbic acid, potassium sorbate and calcium sorbate have the same mechanism of action, and their toxicity is less than that of benzoic acid and nipagin ester. The daily allowance is 25mg/Kg, 5 times of benzoic acid and 2.5 times of nipagin ester, which is a relatively safe food preservative. In China, it can be used in soy sauce, vinegar, flour paste, jam, pickles, canned food and some wines.

2. Benzoic acids include benzoic acid and sodium benzoate; Benzoic acid is also called benzoic acid, so sodium benzoate is also called sodium benzoate. Benzoic acid is insoluble in water at room temperature, slightly volatile in air (especially hot air) and hygroscopic, about 0.34 g/100 ml at room temperature; But soluble in hot water; Also soluble in ethanol, chloroform and non-volatile oil. Sodium benzoate is used in all cases; Benzoic acid and sodium benzoate have similar properties and corrosion resistance. Let me briefly introduce sodium benzoate: sodium benzoate is mostly white particles, odorless or slightly benzoin-scented, slightly sweet and astringent; Soluble in water (normal temperature) about 53.0g/ 100ml, with a PH of about 8; Sodium benzoate is also an acidic preservative, which has no bactericidal or bacteriostatic effect in alkaline medium. The best antiseptic PH is 2.5-4.0, and the bactericidal effect of 5% solution is not very good at PH5.0. Sodium benzoate is lipophilic, which easily penetrates the cell membrane and enters the cell body, interfering with the permeability of the cell membrane and inhibiting the absorption of amino acids by the cell membrane; Enter the cell to ionize and acidify the alkali storage in the cell, inhibit the activity of respiratory enzymes in the cell, and prevent the condensation reaction of acetyl-CoA, thus achieving the purpose of food preservation.

Benzoic acids can be used in flour sauces, jams, pickles, canned foods and some alcoholic beverages in China. Now the state clearly stipulates that benzoic acids cannot be used in jelly foods. Benzoic acids are highly toxic, which limits the use of benzoic acid and its salts, and many countries have replaced them with potassium sorbate.

3. Nipagin esters (that is, parabens) include methyl paraben, ethyl paraben, propyl paraben, butyl paraben, etc. Butyl p-hydroxybenzoate has the best antiseptic effect. Ethyl p-hydroxybenzoate and propyl p-hydroxybenzoate are mainly used in China, and butyl p-hydroxybenzoate is the most used in Japan. The biggest feature of nipagin esters is that there are many series products and wide antibacterial spectrum; The antiseptic mechanism is to destroy the cell membrane of microorganisms, denature the protein in cells, and inhibit the activities of respiratory enzymes and electron transfer enzymes in cells. The antibacterial active components of nipagin ester mainly work in molecular state. Because the hydroxyl group in the molecule has been lipidated and is not ionized, and the ionization constant of the para-phenol group is very small, more than 60% still exists in molecular state when the solution PH is 8, so the antibacterial effect of nipagin ester has good effect in a wide range of pH 4-8.

Because nipagin esters are insoluble in water, they are usually dissolved in sodium hydroxide, acetic acid and ethanol before use. In order to give full play to the anti-corrosion effect, it is best to mix two or more of these lipids. Ethyl p-hydroxybenzoate is generally used in soy sauce and vinegar, while propyl p-hydroxybenzoate is generally used in some fruit drinks and fruits and vegetables. When in use, it can be added, dipped, coated and sprayed, and coated on the surface or absorbed inside. The presence or absence of spores and spores has a great influence on the antiseptic effect of preservatives. Under the condition of using the same amount of preservatives, the more serious the food pollution, the more original bacteria, and the worse the preservative effect. Relevant data show that from the perspective of microbial proliferation process, it is a slow induction period at first, and after the induction period, it will rapidly aggregate into logarithmic phase, and the proliferation is very vigorous. Because the role and dosage of food additives are limited all over the world, it usually only inhibits microorganisms and prolongs the induction period in the process of microbial proliferation. If the food has been seriously contaminated by microorganisms, it will not help to use preservatives again. For example, when food is seriously polluted by microorganisms, sorbic acid becomes a nutrient of microorganisms, which can not only inhibit microbial reproduction, but also accelerate food spoilage. Therefore, it is also very important to pay attention to and maintain good hygienic conditions when using food preservatives, reduce the number of original bacteria in food, and also use other means such as sterilization or packaging to minimize the possibility and degree of microbial contamination of food.