Colorants can be divided into synthetic colorants and natural colorants according to their sources. According to the structure, synthetic colorants can be divided into azo, anthracene and diphenylmethane. Natural colorants can be divided into pyrroles, polyenes, ketones, quinones and polyphenols. According to the solubility of colorants, they can be divided into fat-soluble colorants and water-soluble colorants. Edible natural pigments Edible pigments (Figure 4) Natural pigments Edible natural pigments mainly refer to pigments extracted from animal and plant tissues, mostly plant pigments, including microbial pigments, animal pigments and inorganic pigments. Most of them come from plant tissues, especially fruits and vegetables. High safety, and some of them have nutritional functions (such as β-carotene). According to the source, it can be divided into plant pigment (such as chlorophyll), animal pigment (such as lac red) and microbial pigment (such as monascus pigment). In addition, it can also include some inorganic pigments. According to the structure, it can be divided into chlorophyllin, isoprene (β-carotene), polyphenol (anthocyanin), ketone (curcumin), quinone (lac red), beet red and caramel color. The color of natural colorants is easily influenced by metal ions, water quality, pH value, oxidation, light and temperature, and it is generally difficult to disperse, with poor dyeability, poor compatibility between colorants and high price. [4] By the end of 1998, there were 48 kinds of edible natural pigments, including natural β-carotene, beet red, turmeric, safflower yellow, shellac red, chilli red, pepper orange, caramel color (produced without ammonia), caramel color (produced with ammonia), red rice red and chrysanthemum yellow extracts. Cocoa shell color, monascus rice, monascus red, sunflower red, black galenical red, gardenia yellow, vetiver grass, seabuckthorn yellow, roselle red, acorn shell brown, NP red, push Hui Ke brown, mulberry red, natural mustard red and Rosa laevigata brown; Curcumin, peanut red, grape skin red; Orchid spindle fruit red; Algae blue, plant carbon black, strong yellow, Lithospermum red; Tea yellow pigment: tea green pigment, orange, oleoresin orange (cochineal orange/norcochineal orange), cochineal red, iron oxide (black), etc. Commonly used natural colorants include chili red, beet red, monascus red, cochineal red, sorghum red, sodium copper chlorophyllin, turmeric, gardenia yellow, carotene, phycocyanin, cocoa pigment, caramel pigment and so on. Characteristics of natural pigments: the content and stability of pigments are not as good as those of synthetic pigments. Because it comes from fruits, vegetables, animals and plants, it is safe for human body, can better imitate the color of natural objects, and has a natural tone; Higher cost; Short shelf life. Edible artificial pigment, water-soluble curcumin, synthetic colorant, and the raw materials of synthetic colorant are mainly chemical products. It is mainly a chemically synthesized organic pigment. According to chemical structure, it can be divided into azo pigments and non-azo pigments. According to solubility, it can be divided into oil-soluble pigments and water-soluble pigments. Oil-soluble pigments are toxic, and are basically no longer used as food pigments in various countries. In addition, there is a kind of lake, which is a special colorant made of water-soluble pigments deposited on an approved insoluble substrate. It can contain different pure pigments (10 ~ 40%) and moisture, and is insoluble in most solvents. Synthetic pigments listed in China's Hygienic Standard for the Use of Food Additives (GB 2760- 1996) include carmine, amaranth, sunset yellow, erythrosine, lemon yellow, magenta, indigo, brilliant blue, titanium dioxide (white pigment) and so on. Compared with natural pigments, synthetic pigments are brighter in color, less prone to fading and lower in price. [5] By the end of 1998, the synthetic pigments approved and allowed by the state were: carmine, carmine aluminum lake, carmine aluminum lake and amaranth; Naked red aluminum lake, new red, new red aluminum lake. Lemon yellow, lemon yellow aluminum lake, sunset yellow, sunset yellow aluminum lake, bright blue; Brilliant blue aluminum lake, indigo, indigo aluminum lake, sodium copper chlorophyllin, B- carotene, titanium dioxide, temptation red; Acid red, ***2 1 species. There are 9 kinds of synthetic pigments widely used in China, including amaranth, carmine, magenta, lemon yellow, sunset yellow, indigo, brilliant blue, latosolic red, seductive red and so on. The characteristics of artificial pigment: bright color; A variety of colors; Stable performance; Strong coloring power; Strong firmness; Easy color matching; Easy to use; Low cost; Widely used; The dosage and scope of use are strictly limited. Countries all over the world, especially developed countries in the west, have not only done a lot of investigation and study on the influence of pigments on human health, but also have strict regulations on the management of edible pigments and the use of synthetic pigments, and many kinds of synthetic pigments are prohibited or strictly restricted. In Denmark, researchers suggest that instead of banning the addition of pigments to food, it is better to indicate the types of pigments added on food labels. In this way, consumers can decide whether to buy food. In addition, the Danish government also decided to ban the use of pigments in basic foods and required that all added pigments must be indicated on food labels. Denmark took this action to ensure that people who are allergic to certain pigments eat basic foods without pigments. Other countries restrict the use of certain pigments, especially azo pigments, in food more strictly. According to relevant data, through efforts, the varieties of edible synthetic pigments that can be legally used have been greatly reduced. According to relevant data, there are more than 100 kinds of synthetic pigments in the world, and there are 27 kinds of synthetic pigments approved for use in Japan, of which 16 kinds have been banned. The United States 1960 allowed 35 kinds of synthetic pigments, and now only 7 kinds are left. Sweden, Finland, Norway, India, Denmark, France and other countries have already banned the use of azo pigments, and some countries such as Norway have completely banned the use of any chemical synthetic pigments. In addition, some countries have banned the addition of synthetic pigments to meat, fish and their processed products, fruits and their products, condiments, baby food, cakes and other foods. The use of edible pigments is restricted in China, and the addition of synthetic pigments in food is also strictly restricted in China: synthetic pigments cannot be used in meat and its processed products, fish and its processed products, spices such as vinegar, soy sauce and fermented bean curd, fruits and their products, milk and dairy products, baby food, biscuits and cakes. Only a small amount of soft drinks, cold drinks, candy, mixed wine and fruit juice can be used, generally not exceeding110000. [15] There are six kinds of edible synthetic pigments approved for use in China, namely amaranth, carmine, tartrazine, sunset yellow, indigo and brilliant blue. Although the harmfulness of these six kinds of edible synthetic pigments is inconclusive, they have no nutritional value and are not helpful to human health. Try not to eat it if you can. In fact, driven by huge economic benefits, the phenomenon of excessive use of synthetic pigments in food in China has been repeatedly banned. When buying food, everyone must be careful not to pursue the color of food too much.