Protein is an extremely important structural molecule and active substance, and an essential nutrient for the human body. Proteins are made of carbon, hydrogen, oxygen and nitrogen atoms, and some also contain sulfur atoms. The chemical structure of protein is very complex, and the chemical structure of most proteins has not been elucidated yet. At present, proteins can only be classified according to their chemical composition, solubility, form and nutritional value. According to the chemical composition, it can be divided into simple protein and combined protein.
Chemical structure and physicochemical properties of soybean protein
The content of soybean protein is about 40% of that of soybean, 90% of which can be precipitated at pH 4.5~4.8, of which the precipitated part is soybean globulin, and the unprecipitated part is soybean whey protein. The protein content in soybeans is 4 to 5 times that of cereal foods. The amino acid composition of soybean protein is similar to that of milk protein. Except for slightly lower methionine, the rest of the essential amino acids are richer. It is a plant-based complete protein. According to the experiment of FAO/WHO in 1985 The results show that for people over 2 years old, the physiological potency of soybean protein is 100, which is the same as that of egg and milk protein. The CAS number of soy protein is 9010-10-0.
Physiological function and effect of soybean protein
1. Lower plasma cholesterol levels
Studies have shown that eating 47g of soy protein per day can reduce low-density lipoprotein (LDL) cholesterol, total cholesterol and triglycerides in the blood without reducing high-density protein (HDL) cholesterol. For people with high cholesterol levels, as long as they consume 25g of soybean protein per day, it can have a significant effect. Because high plasma cholesterol is the main factor leading to heart disease and atherosclerosis, soy protein plays an important role in preventing and treating cardiovascular diseases and ensuring heart health.
2. Improve kidney function
In experiments on animals suffering from kidney disease, it was found that the test group fed with soybean protein food had a high survival rate and a low degree of kidney damage. Studies have pointed out that eating soy protein in patients with kidney disease can achieve the same effect as restricting soy protein foods, that is to say, soy protein can be used as a relatively safe protein source for patients with kidney disease.
3. Reduce bone loss
Animal protein is rich in sulfur-containing amino acids, and a large intake will accelerate the loss of urinary calcium, leading to a negative calcium balance in the body. The content of sulfur-containing amino acids in soybean protein is low, which causes the least urinary calcium loss among all high-protein foods. Animal experiments have shown that eating soybean protein can prevent bone loss, thereby reducing the risk of osteoporosis.
4. Reduce the incidence of breast cancer
A long-term daily diet study confirmed that the probability of breast cancer decreased in people who consumed a lot of soy foods.
5. Others
Soy protein has a weight loss effect, which may reduce the incidence of human obesity by reducing hunger and increasing metabolic rate. Soy protein also has antioxidant and cancer suppressor effects.