What kind of protein is high quality?

Protein is one of the essential nutrients for our body Dietary guidelines clearly point out that it is necessary to ensure the daily intake of protein, especially the intake of high-quality protein and essential amino acids So, which are high-quality proteins? There are two main indexes to judge the quality of protein: the digestibility of protein and the proportion of essential amino acids In general, the digestibility of animal protein is higher than that of plant protein, and cooked protein digests better than raw protein Because dietary fiber in plants can hinder the digestion of protein to some extent, the digestibility of protein from plants is usually not as high as that from animals In addition, the retention time of food in the intestine is basically fixed, and it will not stay for a long time due to the difficulty of plant protein digestion So part of the protein in the plant may not have been "sucked" out by the body, and it will be discharged from the body   In addition, the human body does not absorb the complete protein, so it needs to decompose the protein into amino acids, or a shorter amino acid chain (i.e active peptide) to be able to absorb In the process of food cooking, the heat will break part of the amino acid chain, so cooked meat digests better than raw meat And heating also destroys some substances that block protein digestion, such as antitrypsin in raw beans Essential amino acids cannot be synthesized in human body and must be obtained from food Therefore, the amount of essential amino acids contained in food protein becomes the key index to evaluate the quality of the protein The reason why cereal protein can't be regarded as high quality protein is that the digestibility of protein from plants is low, and the proportion of essential amino acid lysine in cereal protein is low Foods rich in high-quality protein include meat, eggs, milk, soybeans and nuts.