Food preservatives summary (worth collecting)

Preservatives are divided into two categories according to their sources, chemical preservatives and natural preservatives.

Chemical preservatives are divided into organic preservatives and inorganic preservatives. The former mainly includes benzoic acid, sorbic acid, etc., and the latter mainly includes sulfites and nitrites.

Natural preservatives, usually extracted from metabolites of animals, plants and microorganisms, such as streptococcin lactate.

Chemical food preservatives

At present, most of the chemical preservatives used in the Market in China are mainly benzoic acid and its sodium salts, sorbic acid and its potassium salts, propionic acid and its salts, parabens (parabens), dehydroacetic acid and its sodium salts, sodium lactate, fumalic acid and so on.

Benzoic acid and its sodium salt Benzoic acid and its sodium salt is currently one of the most commonly used preservatives in China's food processing industry, mainly used for the antiseptic of liquid foods such as beverages (such as: soda, juice, soy sauce, canned food, wine, etc.). Benzoic acid, also known as benzoic acid, molecular formula c7h6o2. Benzoic acid is a monobasic aromatic carboxylic acid. Benzoic acid is lipophilic and easily penetrates through the cell membrane and enters the cell body, thereby interfering with the permeability of the microbial cell membrane and inhibiting the absorption of amino acids by the cell membrane. The benzoic acid molecule entering the cell body ionizes the alkaline substances in the acidifying cell and can inhibit the activity of the cellular respiratory enzyme system, which has a strong blocking effect on acetyl-CoA condensation reaction, thus playing a preservative effect on food. Benzoic acid has a wide range of antibacterial spectrum in a slightly acidic environment, and its inhibition of bacteria is strong, the inhibition of yeast and mold is weak, and the optimal pH value of antiseptic is 2.5 to 4.0. Because benzoic acid is difficult to dissolve in water, sodium benzoate is often replaced in practical applications. Sodium benzoate can only exert antiseptic effect under the condition of free benzoic acid, and in more acidic foods, sodium benzoate has a good antiseptic effect. Benzoic acid and its sodium salt are relatively safe food chemical preservatives, used according to the hygienic standards of food additives, and no toxic side effects have been found.

Sorbic acid and its potassium salt Sorbic acid is 2,4-hexadienoic acid, also known as catalpaic acid, with the molecular formula c6h8o2. Sorbic acid (potassium sorbate) is the most used preservative and is used in most countries. Sorbic acid is an unsaturated fatty acid, and its bacteriostatic mechanism is to use its own double bond to bind to the thiol group of the enzyme in the microbial cell to form a covalent bond, making it inactive and destroying the enzyme system. In addition, sorbic acid can also interfere with the transmission function, such as the transmission of cytochrome C to oxygen, as well as the function of cell membrane energy transfer, inhibit the proliferation of microorganisms, so as to achieve the purpose of antiseptic. Sorbic acid and its potassium salts can effectively inhibit mold, yeast and gas spoilage bacteria, but are almost ineffective against anaerobic bacteria and lactic acid bacteria. The antiseptic effect of sorbic acid decreases with the increase of phH, but its suitable pH range is wider than that of benzoic acid, and it is appropriate to have a pH value of 5 to 6 or less, which is also an acidic preservative. Sorbic acid can participate in the normal metabolism of the human body, and is eventually oxidized into co2 and water, which is basically harmless to the human body and has no adverse effect on food flavor, and is currently recognized as one of the safest food chemical preservatives. However, because the price of sorbic acid is higher than that of benzoic acid, its application is limited, and it is currently only used in high-end foods.

Propionic acid and its salt Propionic acid is a monobasic acid, colorless oily liquid. It has an antibacterial effect on inhibiting the synthesis of β-alanine by microorganisms. Propionate mainly has sodium propionate and calcium propionate, their antiseptic mechanism is the same, are transformed into propionic acid in the human body, monomeric propionic acid molecules can form a high osmotic pressure outside the mold cells, so that the mold cells are dehydrated, lose fecundity, and can also penetrate the mold cell wall, inhibit the activity in the cell. Among them, propionic acid is an intermediate product of normal metabolism of the human body, which can be metabolized and utilized, safe and non-toxic. Propionate is an acid-type preservative, in an acidic environment in order to produce bacteriostatic effect, is currently mainly used for bread, pastry food, can play a better anti-mildew effect.

Parabens (parabens) Parabens include methylparaben, ethylparaben, propylparaben, isopropylparaben, butylparaben, isobutyl parahydroxybenzoate, isobutyl parahydroxybenzoate, heptyl parahydroxybenzoate and the like. The bacteriostatic mechanism of parabens is to inhibit the activity of the respiratory system and electron delivery enzyme system of microbial cells, and can destroy the structure of microbial cell membranes, thereby playing an antiseptic role. The antiseptic effect of parabens does not change with the change of pH value, and has a good effect in the pH range of 4 to 8, and has a broad-spectrum antibacterial effect on mold, yeast and bacteria, but has a poor effect on gram-negative bacilli and lactic acid bacteria. The antibacterial properties of parabens are related to the length of the alkane chain, and the longer the alkane chain, the stronger the antibacterial effect. The antibacterial effect of parabens is stronger than that of benzoic acid and sorbic acid, and the toxicity is lower than that of benzoic acid but higher than that of sorbic acid. The biggest disadvantage is that it has a special odor and is difficult to dissolve in water, so it is usually dissolved in sodium hydroxide, acid, ethanol first, and then used. In order to better exert the antiseptic effect, it is best to mix 2 or more of these esters.

Dehydroacetic acid and its sodium salt dehydroacetic acid, molecular formula c8h8o4 it and its sodium salt are white or light yellow crystalline powder, has a strong antibacterial ability, especially strong antibacterial ability to mold and yeast. It is an acidic preservative and is basically ineffective against neutral foods. It is stable to light and heat, degraded to acetic acid in aqueous solution, and is non-toxic to the human body. It is a broad-spectrum preservative that is widely used in the preservation of preservatives in meat, fish, vegetables, fruits, beverages, pastries, etc.

Sodium lactate colorless or slightly yellow transparent liquid, no peculiar smell, slightly salty bitter taste, mixed in water, ethanol, 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 preservative, mainly used in meat and poultry products, which has a strong inhibitory effect on meat food bacteria. Such as E. coli, Clostridium botulinum, Listeria and so on. By inhibiting pathogenic bacteria in food, the safety of food is enhanced. Enhances and improves the flavor of meat and extends shelf life. Sodium lactate has good dispersibility in raw meat and good adsorption of water, thereby effectively preventing dehydration of raw meat and achieving freshness and moisturizing effect. It is mainly suitable for roast meat, ham, sausage, chicken, duck and poultry products and sauce and brine products. Reference formula for preserving freshness in meat products: sodium lactate: 2%, sodium dehydroacetate 0.2%.

Dimethyl fumarate is a new type of anti-mildew preservative vigorously developed at home and abroad, which can inhibit more than 30 kinds of mold and yeast, and its antibacterial properties are not affected by the pH value, and have the advantages of high efficiency and broad spectrum, high safety and low price. Its comprehensive antibacterial and antiseptic properties are superior and have strong biological activity. Due to sublimation, it has fumigation, so it has the dual effect of contact sterilization and fumigation sterilization. Low toxicity, after entering the human body, it quickly becomes fumaric acid, a normal component of human metabolism, and the application is reproducible.　　Dimethyl fumarate is also widely used in vegetables, fruits, Chinese herbal medicines, tobacco, cosmetics, textiles, film, tape, floppy disk, leather, paper books and materials for antiseptic, mildew and insect repellent. Dimethyl fumarate has great application value and good economic benefits in food preservation. Especially under the conditions of high temperature and high humidity, it can avoid the occurrence of food spoilage and decay, dry cracking and aging taste difference on the appearance, which seriously affect production and market sales.

Inorganic salt preservatives mainly include nitrogen-containing nitrates and nitrites and sulfur-containing ones. The toxicity of nitrates is mainly caused by being reduced to nitrite in food, water or in the body. Nitrite is one of the most toxic substances in food additives, after ingestion by the human body, it can bind to hemoglobin to form methemoglobin and lose its oxygen-carrying function, and can be suffocated in severe cases. The lethal amount to the human body is 4 to 6 g/kg body weight. Under certain conditions, it can be converted into nitrosamines with strong carcinogenicity. This type of preservative is mainly used for the preservation and color protection of meat products. Sulfur-containing sulfites and metabisulfites and other active ingredients are sulfurous acid molecules, and the bactericidal mechanism of sulfurous acid is mainly to consume o2 in food to cause gaseous microorganisms to die due to lack of oxygen, and can inhibit the activity of enzymes in some microbial physiological activities. Because the sulfur dioxide residue after the use of these salts can cause allergic reactions, especially for asthma patients, it is now generally only included in special preservatives. For example, the Guangxi local standard db45/319-2007 "Quality and Safety Requirements for Fresh Wet Rice Flour" stipulates that the residual amount of so2 in rice flour should be lower than the detection limit of the method. Natural food preservatives

Natural food preservatives generally refer to a class of substances with preservative effects that are directly isolated from animals and plants, or isolated from their metabolites. Natural preservatives have the advantages of strong antibacterial properties, safe and non-toxic, good water solubility and a wide range of effects that synthetic preservatives do not have. With the improvement of people's living standards and the progress of science and technology, people are paying more and more attention to natural food preservatives.

Natural food preservatives can be divided into three categories according to their source: preservatives derived from plants, animals and microorganisms

1, pectin decomposition Pectin is mainly found in apples, grapes, citrus and other fruits and vegetables. The enzymatic decomposition products of pectin have a strong antibacterial effect, especially suitable for the inhibition of E. coli. Pectin decompositions are effective under acidic conditions and are most antibacterial at pH less than 6. At present, foreign countries will cooperate with other natural preservatives and are widely used for the preservation of sauerkraut, salted fish and other foods

2, agar oligosaccharides Extracted from seaweed, the main component is agarose, its enzyme decomposition is agar oligosaccharides, it has a strong bacteriostatic and prevent starch regeneration and aging effect, in the concentration of 3.11%, can effectively reduce colony production. At present, it is widely used in noodles, bread and pastries.

3. Chinese herbal extracts Allicin and garlic in garlic can effectively resist portuguese; Perilla leaf extract has a broad-spectrum antibacterial effect, and has a good inhibitory effect on various coccidioides and bacilli; Forsythol in forsythia extract can effectively inhibit a variety of gram-positive bacteria and negative amaranth, prolonging the shelf life of food; In addition, tea polyphenols, konjac extract mannan, corn whisker extract, etc. have good antibacterial effects.

Natural preservatives derived from animals

1. Propolis propolis has a strong bacteriostatic effect, and its bacteriostatic effect is comparable to that of various chemical preservatives. It is generally believed that the antiseptic preservation mechanism of propolis is first of all that propolis can kill a variety of bacteria, fungi, viruses and protozoa, followed by propolis has a good film-forming effect, the film formed can reduce the pollution of microcontensions, and can also reduce the exchange of food and external gases. The propolis extract is directly added to human milk, health care oral liquid and beverages have a good antiseptic and freshness preservation effect. At present, the price of propolis raw powder is about 300 yuan per kilogram.

2, chitosan chitosan, also known as carapace cord, is a polysaccharide substance extracted from crab shells and shrimp shells. The principle of chitosan and its derivatives as an antiseptic preservative is similar to that of propolis, mainly by using its good film-forming properties and strong antibacterial ability. Chitosan is effective against bacteria, yeast, and mold. Studies have shown that it can be used for the preservation of beverages, sauces, fruits and vegetables, and is currently the best candidate for natural antibacterial preservatives.

3. Lysozyme general protein contains about 0-3% of lysozyme, so it can be extracted from protein. At present, the commercial production is egg white lysozyme, which has a strong bactericinizing effect on gram-positive bacteria, bacillus subtilis, bacillus subtilis, and gas-forming spore-forming bacteria under the condition of phH 7 and temperature of 5o °C. Since the hydroxyl groups and acids in food can affect the activity of lysozyme, it is generally used in conjunction with substances such as wine, phytic acid, and glycine. It has been widely used for preservative preservation of aquatic products, meat products, fresh seafood, pastries and wine and other beverages, but the price is high, about 2400 yuan per kilogram.

4. Protamine protein Protamine is a polycationic peptide found in the sperm core of fish, which has broad-spectrum bacteriostatic activity, which can inhibit the growth of Bacillus subtilis, Bacillus macrospora, Bacillus licheniformis, etc., and also has obvious inhibitory effects on gram-positive bacteria, yeast and mold. The mechanism of action of protamine destroys the cell wall of microorganisms, dissolves the cell membrane, causes cell leakage, protamine is used in conjunction with other natural additives, glycine, sodium acetate, etc., the antibacterial effect is better, the applicable food preservative range is also wider, the current price of food grade protamine protein is about 600 yuan per kilogram.

Natural preservatives derived from microorganisms

1. Streptococcus lactate (nisin) nisin has a strong inhibitory effect on Gram-positive bacteria, especially bacteria that can form spores, but has no effect on Gram-positive bacteria, yeast and mold, and can inhibit staphylococcus, streptococcus, micrococci, and most of the spores of Clostridium and Bacillus. Nisin has strong activity under acidic conditions, reaching maximum activity at ph<4.5. The combination of nisin and lactic acid inhibits Staphylococcus aureus and Salmonella in meat. The combination of nisin with citrate and phosphate can also improve its inhibition effect on gram-negative bacteria. This antibacterial effect of nisin makes it used as a preservative in the antiseptic work of dairy products, beer and other alcoholic beverages, acidic canned food and meat products, etc., and the market price of its preparation is about 650 yuan per kilogram.

2, natamycin Natamycin can kill and inhibit almost all yeast and mold, but it is ineffective against bacteria and protozoa. The antimicrobial spectrum of natalmyces cord is complementary to nisin, and the two can be used together. The antibacterial effect of natamycin is 50 to 300 times stronger than that of commonly used sorbic acid, and 1.0 to 6.0 mg l-1 can inhibit most molds. Natamycin is often used in the surface treatment of cheese, dry sausages, but also in the protection of yogurt, wine and fruit juice.　　At present, many natural food preservatives have been put on the market, but the higher prices have hindered their further application. It is believed that in the near future, with the progress of science and technology, the production cost of natural preservatives will be greatly reduced, and the application of chemical synthetic preservatives in food and other aspects will completely replace chemical synthetic preservatives.

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