Lysine - an Absolutely Essential Amino Acid in Soybean Proteins from the Russian Selection
Abstract
The study aims to evaluate the content of lysine, a valuable and important amino acid for food and feed purposes in the protein composition of soybean grain in varieties bred in the Federal Scientific Centre of All-Russian Scientific Research Institute of Soybean (Russian Federation) from 2003 to 2021. Lysine is the first limiting amino acid which is essential for normal metabolism of proteins from food and feed. If this amino acid is not sufficient, no matter how much protein is ingested in humans and animals, it will not be properly metabolized. Its high requirement (3-5 g per day in humans) makes it one of the most important essential amino acids. A high content of this amino acid is found in soybeans. A laboratory study of the amino acid composition of soybean protein was carried out in 2018 -2020 by diffuse light reflection in the infrared region of the spectrum on a FOSS NIR Systems 5000 model IR scanner. It was found that the lysine content in the protein of soybean grain of Amur varieties, ranged from 6.0 to 6.3% of total protein, which is significantly higher than varieties of European breeding. In all of the studied varieties, the Institute's selection has an amino acid index of lysine ranging from 109 to 113%, which significantly exceeds the FAO/WHO standard. The highest lysine indices were observed for the variety Kruzhevnitsa (6.3%).
