Requirements for the use of food additives:
1. Safety toxicology evaluation proves that long-term use within the use limit is safe and harmless to human body.
2. It does not affect the physical and chemical properties of food senses and should not destroy the nutritional components of food.
3. Food additives should have strict hygiene standards and quality standards, which have been officially approved and promulgated by People's Republic of China (PRC) and the Ministry of Health.
4. Food additives can be destroyed or eliminated during processing, cooking or storage after reaching a certain purpose.
5. Food additives shall not be used to cover up the defects of food or as a means of forgery. Non-designated manufacturers, no production license and contaminated or deteriorated food additives shall not be used.
Common food additives:
First, antioxidants
1. Action mechanism of antioxidants
The mechanism of action of antioxidants is very complicated, and there are many possibilities. If some antioxidants are easily oxidized, they react with oxygen first, thus protecting food. For example, some antioxidants such as VE can release hydrogen ions to decompose and destroy peroxides produced in the process of automatic oxidation of oil products, so that they cannot form aldehyde or ketone products, such as tdpa lauryl ester. Some antioxidants can combine with the peroxides they produce to form hydroperoxides, which interrupt the oxidation process of oils and fats, thus organizing the oxidation process and forming antioxidant free radicals themselves, but antioxidant free radicals can form stable dimers or combine with peroxide free radicals ROO. Combine to form stable compounds. Such as BHA, BHT, TBHQ, PG, tea polyphenols, etc.
2. Several commonly used fat-soluble antioxidants
(1)BHA: butylated hydroxyanisole. Because it has good effect retention after heating, it can effectively preserve food. It is one of the antioxidants widely used in the world at present, and it is also one of the antioxidants commonly used in China. When used together with synergists such as citric acid, its antioxidant effect is more obvious. Generally speaking, BHA is considered less toxic and safer.
(2)BHT: dibutylhydroxytoluene. Compared with other antioxidants, it has high stability, good heat resistance, little influence at ordinary cooking temperature and good antioxidant effect, and is very effective for long-term preserved food and baked food. It is a cheap antioxidant, which is widely used in the world, especially in the processing of aquatic products. Generally used in conjunction with BHA, citric acid or other organic acids are used as synergists. Compared with BHA, the toxicity is slightly higher.
(3)PG: propyl gallate. Stable to heat. The antioxidant effect of PG on lard is stronger than BHA and BHT. Low toxicity.
(4)TBHQ: tert-butyl hydroquinone. It is a relatively new phenolic antioxidant with good antioxidant effect.
Second, bleach.
All these substances can produce sulfur dioxide, which generates sulfurous acid when it meets water. In addition to bleaching, it also has antiseptic effect. In addition, because sulfurous acid has strong reducibility, it can consume oxygen in fruits and vegetables, inhibit the activity of oxidase and prevent the oxidative damage of vitamin C in fruits and vegetables.
Sulfite can be metabolized into sulfate in human body and excreted from urine through detoxification process. Sulfite compounds are not suitable for animal food, so as not to produce unpleasant smell. Sulfite has a destructive effect on vitamin B 1, so foods with high B 1 content, such as meat, grains, dairy products and nuts, are not suitable. Because it can cause allergic reactions, its use is strictly restricted in the United States and other countries.
Three. coloring agent
Pigment, also known as pigment, is a substance that can improve the sensory characteristics of food after coloring. According to its nature and source, edible pigments can be divided into two categories: edible natural pigments and edible synthetic pigments.
1. Edible synthetic pigments belong to synthetic pigments. Edible synthetic pigments are characterized by bright color, stable properties, strong coloring power, strong fastness, arbitrary color, low cost and convenient use. But most synthetic pigments are harmful to human body. The toxicity of synthetic pigments is that their chemical properties are directly toxic to human body; Some or harmful substances are produced during metabolism; It may also be contaminated by arsenic, lead or other harmful compounds in the production process.
At present, the synthetic pigments allowed to be used in China are amaranth, carmine, scarlet (cherry red), magenta, seduction red, lemon yellow, sunset yellow, brilliant blue, indigo and their respective aluminum lakes. And synthetic beta-carotene, sodium copper chlorophyllin and titanium dioxide.
2. Edible natural pigments are mainly extracted from animal and plant tissues. The composition of human natural pigment is complex, and the function of purified natural pigment may be different from the original. Moreover, its chemical structure may also change during the refining process; In addition, in the process of processing, there is the possibility of pollution, and it cannot be considered that natural pigments must be pure and harmless.
Synthetic food pigments, like other food additives, need strict toxicological evaluation to achieve the purpose of safe use. Including ① chemical structure, physical and chemical properties, purity, existing form in food, degradation process and degradation products; ② Retention, distribution, metabolic transformation and excretion of food in tissues and organs after being absorbed by the body; ③ Biological changes caused by itself and its metabolites in vivo, as well as possible toxicity to the body and its mechanism. Including acute toxicity, chronic toxicity, effects on reproduction, embryo toxicity, teratogenicity, mutagenicity, carcinogenicity, sensitization and so on.
Fourthly, fixing agent.
Color fixative is also called color developer. In the process of food processing, in order to improve or protect the color of food, in addition to directly coloring food with pigments, it is sometimes necessary to add a proper amount of color developing agent to make the products show good color.
1. Chromogenic principle and other functions of chromogenic agent: ① Chromogenic function, in order to make meat products appear bright red, more nitrate (sodium or potassium) or nitrite is added during processing. Nitrate is reduced to nitrite by bacterial nitrate reductase. Nitrite will produce nitrous acid under acidic conditions. At room temperature, it can also decompose to produce nitroso (NO), and the generated nitroso will quickly react with myoglobin to produce stable, bright and bright red nitroso myoglobin. Therefore, meat can remain stable and bright. ② Bacteriostasis: Nitrite in meat products has a certain inhibitory effect on the proliferation of microorganisms.
2. The application of chromogenic agent
Nitrite is one of the substances with strong acute toxicity in additives, and it is a highly toxic drug, which can turn normal hemoglobin into methemoglobin, lose oxygen carrying capacity and lead to tissue hypoxia. Secondly, nitrite is the precursor of nitroso compounds, and its carcinogenicity has attracted international attention. Therefore, all aspects require that the addition of nitrate and nitrite be limited to the lowest level under the condition of ensuring color development.
Ascorbic acid has a high affinity with nitrite, which can prevent nitrosation in vivo and make nitroso compounds almost completely generated. Therefore, adding proper amount of ascorbic acid in the process of meat curing may prevent the production of carcinogens.
Although the use of nitrate and nitrite has been greatly restricted, they are still used at home and abroad. The reason is that nitrite plays a special role in maintaining the color, aroma and taste of pickled meat products, and no ideal substitute has been found so far. The more important reason is the inhibition of nitrite on Clostridium botulinum. However, there are strict requirements on the food used, usage and residue.
Five, enzyme preparation
Enzyme preparation refers to substances with biocatalytic properties extracted from organisms (including animals, plants and microorganisms). It is mainly used to accelerate the food processing process and improve the food quality.
The enzyme preparations allowed in China are: papain-extracted from the milk of immature papaya; And proteases prepared from Aspergillus oryzae, Bacillus subtilis, etc. α-amylase-mainly from Bacillus subtilis; Saccharifying amylase-Aspergillus niger, root enzyme, monascus enzyme and endonuclease are used to produce this enzyme preparation in China; Pectinase produced by Aspergillus Niger, Aspergillus oryzae and Aspergillus flavus.
Six, flavor enhancer
Refers to substances that supplement, enhance and improve the original taste or taste of food. Some are called umami agents.
At present, the flavor enhancers allowed to be used in China are sodium glutamate, disodium guanylate and disodium 5'- inosinate, disodium 5'- inosinate, disodium succinate and L- alanine.
Sodium glutamate is monosodium L- glutamate containing one molecule of crystal water. Soluble in water, crystal water is lost at 150℃, pyroglutamic acid is generated from pyrrolidone at 2 10℃, which is decomposed at about 270℃. Stable to light, racemization occurs when heated under alkaline conditions, and the flavor is reduced. Pyrrolidone is easily converted into pyroglutamic acid when heated under acidic conditions with PH lower than 5, and its flavor is reduced. When neutral, the heating rarely changes.
Glutamate is a low toxic substance. There is no toxicity problem under the condition of general dosage, but nucleotide flavor enhancers are widely found in various foods. No special rules are needed.
In recent years, many meat extracts, yeast extracts, hydrolyzed animal proteins and hydrolyzed vegetable proteins have been developed.
Seven, preservatives
Refers to substances that can inhibit microbial reproduction in food, prevent food from spoilage and prolong the shelf life of food. Preservatives are generally divided into acid preservatives, ester preservatives and biological preservatives.
1. Acid preservatives: benzoic acid, sorbic acid and propionic acid (and their salts) are commonly used. The bacteriostatic effect of these preservatives mainly depends on their undissociated acidic molecules, and their efficacy depends on pH value. The greater the acidity, the better the effect, and they are almost ineffective in alkaline environment.
1. benzoic acid and its sodium salt: benzoic acid is also called benzoic acid. Because of its low solubility in water, its sodium salt is often used. Low cost.
After benzoic acid enters the body, most of it reacts with glycine within 9~ 15 hours to synthesize hippuric acid, which is excreted with urine, and the rest is combined with glucuronic acid to detoxify.
2. Sorbic acid and its salts: also known as sorbic acid. Because of its limited solubility in water, its potassium salt is often used. Sorbic acid is an unsaturated fatty acid, which can participate in the normal metabolic process of the body and be assimilated to produce carbon dioxide and water. Therefore, sorbic acid can be regarded as a component of food, and according to the current data, it can be considered harmless to human body.
3. Propionic acid and its salts: weak bacteriostatic effect and large dosage. Commonly used in bread and cakes, the price is also relatively low.
Propionic acid and its salts have low toxicity and can be considered as normal ingredients of food and intermediate products of normal metabolism of human body.
4. dehydroacetic acid and its sodium salt: It is a broad-spectrum preservative, especially with strong bacteriostatic ability to mold and yeast, which is 2~ 10 times that of sodium benzoate. This product can be quickly absorbed by human body and distributed in blood and many tissues. However, it can inhibit a variety of oxidases in the body, and its safety is suspected, so it has been gradually replaced by sorbic acid, and its ADI value is not specified.
2. Ester preservatives: including parabens (including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, g, etc. ). The cost is higher. It has a wide range of antibacterial effects on mold, yeast and bacteria. It has strong effect on mold and yeast, but poor effect on bacteria, especially gram-negative bacilli and lactic acid bacteria. The mechanism of action is to inhibit the activities of respiratory enzymes and electron transfer enzymes in microbial cells and destroy the cell membrane structure of microorganisms. Its bacteriostatic ability increases with the growth of alkyl chain; Solubility decreases with the increase of ester carbon chain length, but toxicity is the opposite. However, the combined use of ethyl p-hydroxybenzoate and propyl ester can increase its solubility and have synergistic effect. It can be quickly and completely absorbed in the gastrointestinal tract, hydrolyzed into p-hydroxybenzoic acid, excreted from urine and not accumulated in the body. At present, the application of propyl ester and ethyl ester in China is limited.
Third, biological preservatives.
Mainly nisin. Nisin is a metabolite of Streptococcus lactis, which can be obtained by fermentation of Streptococcus lactis. The advantage of nisin is that it can be degraded by proteolytic enzymes in human digestive tract, so it will not be absorbed into the body in its original form, and it is a relatively safe preservative. It will not change the normal intestinal flora like antibiotics and cause drug resistance of other commonly used antibiotics, nor will it be cross-resistant with other antibiotics.
Other preservatives include sodium diacetate, which is both preservative and chelating agent. It has the function of preventing mold propagation on grains and bean products. Sec-butylamine, this product should not be added to processed food, but only used for the preservation of fruits and vegetables during storage. Commercial preservatives, such as Kemeiling and Baoguoling, are all preparations with sec-butylamine as the active ingredient. The increase of carbon dioxide and carbon dioxide partial pressure affects the utilization of oxygen by aerobic microorganisms and can terminate the respiratory metabolism of various microorganisms. For example, a large amount of carbon dioxide in high food can change the pH of food surface, making microorganisms lose the necessary conditions for survival. But carbon dioxide can only inhibit the growth of microorganisms, but not kill them.
Eight, sweeteners
Refers to food additives that give food sweetness. According to the source, it can be divided into: (1) natural sweetener, sugar alcohol and non-sugar. Among them, ① sugar alcohols include xylitol, sorbitol, mannitol, lactitol, maltitol, isomalt and erythritol; ② Non-saccharides include stevioside, licorice, kiwi fruit, mogroside and growth hormone. (2) Synthetic sweeteners, in which sulfonamides are saccharin, sodium cyclamate, acesulfame, etc., and dipeptides include: aspartame methyl, 1-a- aspartyl-n-n-(2,2,4,4-tetramethyl -3- trimethylsulfide) -D- acrylamide (also called alitame). Sucrose derivatives include sucralose, isomaltulose (also known as palatinose) and neosaccharides (fructooligosaccharides).
In addition, according to the nutritional value, it can be divided into nutritional sweeteners and non-nutritional sweeteners, such as sucrose, glucose and fructose, which are also natural sweeteners. Because these sugars not only give food sweetness, but also are important nutrients and provide heat energy for human body, they are usually regarded as food raw materials and are generally not controlled as food additives.
1. saccharin: o-sulfonyl benzoyl, a synthetic sweetener, is widely used all over the world. Its price is low, and its sweetness is 300~500 times that of sucrose. Because of the low solubility of saccharin in water, its sodium salt (saccharin sodium) is stipulated in China's additive standards, which is bitter when used in large quantities. It is generally believed that saccharin sodium is not decomposed and utilized in the body, and most of it is excreted from urine, which does not damage renal function. Does not change the activity of enzyme system in vivo. Saccharin has been widely used in the world for decades, and its toxic effect on human body has not been found yet.
2. Sodium cyclamate: 1958 is widely used as a "generally considered safe substance" in the United States, but it was reported in the 1970s that the product was carcinogenic to animals, and the FAO/ WHO report 1982 proved that it was not carcinogenic. The long-term experiment of FDA in the United States was declared non-carcinogenic in 1984. However, the National Scientific Research Council and the National Academy of Sciences still believe that it can promote cancer and may lead to cancer. So it is still forbidden to eat in the United States.
3. Aspartame. Its sweetness is 0/00 ~ 200 times that of sucrose, and its taste is close to that of sucrose. It is a dipeptide derivative, which is decomposed into corresponding amino acids in the body after eating. China stipulates that it can be used for other foods other than canned foods, and its dosage should be used appropriately according to production needs.
In addition, many dipeptide derivatives containing aspartic acid, such as ritalin, are also amino acid sweeteners, which are synthesized from natural raw materials and have high sweetness.
4. Acesulfame: This product is stable to light and heat (225℃), and the sweetness lasts for a long time. Because saccharin sodium is quickly eliminated from urine after absorption and will not accumulate in the body. It has obvious synergistic effect when used in combination with aspartame 1: 1.
5. Sugar alcohol sweeteners: Sugar alcohol sweeteners belong to a class of natural sweeteners, and their sweetness is similar to that of sucrose, and most of them are low-calorie sweeteners. There are many varieties, such as sorbitol, xylitol, mannitol, maltitol, etc. Some of them exist in natural foods, and most of them are obtained by hydrogenation of corresponding sugars. Its precursor comes from natural food. Because sugar alcohol sweeteners have low glycemic index and do not produce acid, they are often used as sweeteners for patients with diabetes and obesity, and have the function of preventing dental caries. Most of these substances have certain water absorption, which can improve the rehydration of dehydrated food, control crystallization and reduce water activity. However, due to the low absorption rate of sugar alcohols, especially xylitol, a large amount of consumption has a certain ability to cause diarrhea.
6. Stevioside: It is a strong sweet ingredient contained in Stevia rebaudiana and a diterpene-containing glycoside. The sweetness is about 300 times that of sucrose. However, stevioside has poor taste, and it has licorice taste and bitterness at high concentration, so it is often mixed with sucrose, fructose and glucose. , combined with citric acid, malic acid, etc. Fructosyltransferase or α -glucosyltransferase can be used to weaken bitterness or change its structure to correct its shortcomings. A large number of toxicity experiments have been done abroad, and none of them have shown toxic effects. However, in countries that have been consuming this product for a long time, such as Paraguay, it has been used for 100 years, and Japan has used it for more than 15 years, and no adverse side effects have been reported.
In addition, natural sweeteners can be extracted from licorice, Siraitia grosvenorii, somatofen, African bamboo poles, etc.