The secret of“Anti-aging” in food-common synthetic antioxidants

Almost all foods contain substances such as fats, fat-soluble vitamins, phospholipids, and carotenoids that are readily oxidized by oxygen in the air during processing or storage, easy to be affected by temperature, light, oxygen, metal, and so on, and the occurrence of oxidation reaction, causing food flavor, discoloration. In particular, fats and fatty foods, the unsaturated fat in the fats and oils are oxidized to produce a peculiar smell and odour, resulting in food rancidity or spoilage. There are two main methods of anti-aging (oxidation) in food production and storage: physical method and chemical method.

1. The physical method uses the food packing, often take the degassing, the seal and so on means to isolate the outside air and the light as far as possible and the food direct contact, maintains the food quality to be stable, prolongs the shelf life. 

2. The chemical method is an antioxidant used in food processing, which can prevent or retard the automatic oxidation of oil and fat, and prevent the nutrition destruction, Browning and discoloration caused by oxidation in food during storage, chemical methods were used to improve food stability and prolong storage life.

First, the mechanism of antioxidants in the 1930s, people found that guaiac resin has good antioxidant effect on lard, from then on began the application of antioxidants in food. At present, there are hundreds of compounds can be used as antioxidants, and the total number of antioxidants used by countries is about 30, which can be used alone or mixed. Food antioxidant is a kind of food additive which can improve the stability of food and prolong its storage period. There are many kinds of antioxidants, and their mechanism of action is not the same, there are mainly the following: 1. Reduce the oxygen content in the food system by reducing antioxidants. 2. Interrupt the chain reaction of the oxidation process to prevent further oxidation. 3. Destroy and weaken the activity of the oxidase, so that it can not catalyze the oxidation reaction. 4. Blocking a substance that catalyzes and causes an oxidation reaction.

Antioxidants commonly used in food production in food commonly used in food containing fat antioxidants are mainly some oil-soluble antioxidants, including phenolic compounds such as propyl gallate (PG) , 2-tert-butylbenzene-1,4-diol (TBHQ) , tert-butyl-p-hydroxyanisole (BHA) , 2,6-di-tert-butyl toluene (BHT) , their principle is to act as free radical terminators to interfere or delay the proliferation steps in the chain reaction in the most effective way, inhibiting the oxidation of oil.

Propyl gallate (PG) in the early 1940s, PG and other Gallic acids have been used. PG is sensitive to heat and has poor stability in high temperature food. Easy to react with copper, iron and other metal ions are purple or dark purple, light can promote its decomposition. PG has more antioxidant activity than BHA and BHT in all kinds of oils, but its antioxidant activity is not as good as TBHQ. Because PG raw materials mainly rely on a small amount of natural gallnut, so the actual amount is not large, the price is also higher than the general antioxidant.

TBHQ (2-tert-butylbenzene-1,4-diol HQ) TBHQ is a new type of synthetic antioxidant, which is a crystalline powder with good oil solubility. The United States in 1972 by the FDA (US Food and Drug Administration) approval for use, and our country in 1991 only approved the use of oil is one of the * antioxidants. Compared with BHA and BHT, its antioxidant activity is more than twice as high as that of BHA and BHT, and it is highly effective in both vegetable and animal oils. At the same time, TBHQ also has a safer performance, but also has a certain antibacterial effect, can effectively inhibit the growth of some harmful microorganisms.

Tert-butyl-p-hydroxyanisole (BHA) BHA was approved by the FDA in 1948, and was widely used in the United States a few years later, and was also adopted by Q World Industrial countries. The antioxidant activity of BHA to animal fat is stronger than to unsaturated vegetable oil. Some studies have shown that BHA can increase the oxidative stability of lard by 4 times and by 10 times if citric acid is added.

Hexavalent, 2,6-di-tert-butyltoluene (BHT) BHT is another antioxidant widely used in food. Compared with other oil-soluble antioxidants, BHT is stable to heat and reacts with metal ions unchanged. Its antioxidant effect is good, with citric acid, ascorbic acid or BHA compound use, can significantly improve the antioxidant effect. It was approved for use in 1954, but its safety has been questioned in recent years, leading some food manufacturers to stop using BHT, which is widely used because of its low cost, it is still one of the largest producers of antioxidants.

But with the application of these synthetic antioxidants in food more and more widely, the safety of food can not be guaranteed due to the problem of over-standard addition, the rapid development of food industry has put forward higher requirements for antioxidant detection technology. Therefore, it is urgent for the food industry to improve and perfect the detection methods of antioxidants, to innovate constantly, to study more simple, fast and effective detection methods to ensure food safety and human health.