There are two kinds of food additives: chemically synthesized and natural. Natural food additives are extracted from the metabolites of animals, plants or microorganisms. Chemically synthesized food additives are all made by chemical reactions of certain elements or compounds.
At present, there are more than 22 categories 1500 kinds of food additives in China (there are more than 2000 kinds in 45 categories in the United States), most of which are made by synthetic methods, and they are allowed to be used after many strict safety experiments and prescribed approval procedures. Here are two examples: low-salt pickles are easy to deteriorate, and the state allows 0.5 g of chemical preservative sorbic acid to be added to each kilogram of low-salt pickles. So how toxic is sorbic acid? The experimental results on rats show that the dosage of sorbic acid that can kill half of rats is 7.3 grams per kilogram of body weight. If converted into 50 kilograms of body weight, the lethal dose of poisoning is 365 grams of sorbic acid, which is equivalent to eating 1460 kilograms of sorbic acid low-salt pickles. It is conceivable that no one will eat so many pickles at once. Then, considering that eating too much sorbic acid will make pickles taste bad and cause throat discomfort to people who eat it, the added dosage will not affect the taste and cause no harm to people, and it has a good antiseptic effect. Will not cause harm to people, and has a good anti-corrosion effect. Another example is the widely used synthetic pigment, which can interfere with body fat, protein's disease, diarrhea and carcinogenesis in large doses, but the allowable dose is very small. Therefore, it is also very safe under the premise of using the prescribed dose.
Most natural food additives are safe, but some chemical reagents are often used in the extraction process, and there may be reagent residues in the finished products. Natural plants may have used pesticides and have residues. Some natural food additives are as toxic as synthetic food additives. For example, coumarin extracted from leguminous seeds is obviously toxic to the liver, so it is not allowed to be used. At present, there are nearly 2000 kinds of spices that can be extracted from natural plants, and only a few of them are allowed to be used as food additives after safety appraisal. That's the reason. Natural food additives usually have an obvious weakness, that is, they need to be used in large quantities to achieve the expected results. For example, natural pigments not only have poor stability and low coloring power, but also need to use pigments several tens to hundreds times larger than synthetic pigments to achieve ideal coloring effect. Even if it is added in large quantities, it is still easy to fade. Because of these weaknesses, to achieve the same effect as synthetic pigments, it must cost more, which limits its practical value.
Modern food production is inseparable from food additives, and people's appetite is also inseparable from food additives. Otherwise, you will not be able to eat delicious bread, delicious ham and exquisite tofu ... In short, food additives, whether natural or synthetic, may be harmful if they are tested for safety and approved according to regulations, and they are all used according to regulations. Of course, any so-called "food additive" without approval is absolutely prohibited. For example, criminals use sulfur or hydrochloric acid to keep litchi fresh; Hanging white pieces of vermicelli turn white; It is harmful and illegal to use formaldehyde as a preservative for hairdressing products.
This is information. You might as well write your own paper. Recently, readers have an article called "The Betrayal of the God of Japanese Additives" for your reference.