Antioxidants

　　1. The mechanism of action of antioxidants

　　The mechanism of action of antioxidants is complex, and there are many possibilities. If there are antioxidants, they are easily oxidized and react with oxygen first, thus protecting the food. Such as VE. Some antioxidants can release hydrogen ions to decompose and destroy the peroxides generated in the auto-oxidation process of oils and fats, so that they cannot form aldehyde or ketone products such as dilauryl thiodipropionate. Some antioxidants may combine with the peroxides they produce to form hydroperoxides, which interrupt the oil oxidation process, thereby preventing the oxidation process, and themselves form antioxidant free radicals, but antioxidant free radicals can form stable dimer, or with peroxy radical ROO-. combine to form stable compounds.

　　2. Several commonly used fat-soluble antioxidants

　　(1) BHA: butylated hydroxyanisole. It is one of the widely used antioxidants in the world and one of the commonly used antioxidants in China because of its good retention after heating and effective in preserving food. It has a synergistic effect with other antioxidants, and when used with synergists such as citric acid, its antioxidant effect is more significant. BHA is generally considered to be less toxic and relatively safe.

　　(2) BHT: dibutylhydroxytoluene. Compared with other antioxidants, it has high stability and good heat resistance, has little effect under ordinary cooking temperature, and has good antioxidant effect. It is very effective for long-term preservation of food and baked goods. It is an inexpensive antioxidant widely used internationally, especially in aquatic products processing. It is generally used in combination with BHA, and citric acid or other organic acids are used as synergists. Relative to BHA, the toxicity is slightly higher.

　　(3) PG: propyl gallate. Relatively stable to heat. The antioxidant effect of PG on lard is stronger than that of BHA and BHT, and the toxicity is lower.

　　(4) TBHQ: tert-butyl hydroquinone. It is a relatively new class of phenolic antioxidants, and its antioxidant effect is better.

　　bleach

　　These substances can produce sulfur dioxide (SO2), sulfur dioxide and water will form sulfurous acid (H2SO3). In addition to its bleaching effect, it also has a preservative effect. In addition, due to the strong reducibility of sulfurous acid, it can consume oxygen in fruit and vegetable tissues, inhibit the activity of oxidase, and prevent the oxidative damage of vitamin C in fruits and vegetables.

　　Sulfites are metabolized in the body to sulfates, which are excreted in the urine through detoxification processes. Compounds such as sulfites are not suitable for use in animal foods because of the unpleasant smell. Sulfites have a damaging effect on vitamin B1, so foods with more B1 content such as meat, grains, dairy products and nuts are not suitable. Its use in countries such as the United States is severely restricted due to its ability to cause allergic reactions.

　　Colorant

　　Also known as pigment, it is a kind of substance that improves the sensory properties of food after coloring. According to their properties and sources, food coloring can be divided into two categories: natural food coloring and food synthetic coloring.

　　1. Edible synthetic pigments belong to artificial synthetic pigments. The characteristics of edible synthetic pigments: bright colors, stable properties, strong tinting strength, high firmness, any color can be obtained, plus low cost, easy to use. But most of the synthetic pigments are harmful to the human body. Some of the toxicity of synthetic pigments are directly toxic to the human body due to their own chemical properties; some may produce harmful substances in the process of metabolism; they may also be polluted by arsenic, lead or other harmful compounds during the production process.