Amino acid composition of protein of Glycine max (L.) Merr. grain varieties of the Amur breeding

The aim of the study is an indepth examination of the amino acid composition of proteins in the grain of soybean varieties bred at the AllRussian Research Institute of Soybeans over the past 15 years. All studied varieties are included in the State Register of Breeding Achievements of the Russian Federation. Soybean samples for analysis were grown in the collection nursery of the AllRussian Research Institute of Soybeans breeding laboratory (Sadovoye village, Amur Region) in 2018–2023. Fifteen varieties were subjected to biochemical analysis annually. Each variety was studied for 3 years in 4 analytical replicates. The infrared (IR) scanning method was used to quantitatively determine amino acids in ground soybean samples, which ensured rapid analysis of a large number of samples. Protein quality was assessed based on the amino acid score, which compares the content of essential amino acids in the studied protein with the FAO/WHO reference protein. Most of the studied soybean varieties of Amur selection have a high content of valine (up to 6.8 g/100 g protein in the Topaz variety, which is 30% higher than the FAO/WHO standard), isoleucine (up to 6.1 g in the Zolotnitsa, Kukhana and Kitrossa varieties, which is 52.5 % higher than the standard), leucine (up to 8 g in the Lazurnaya variety, which is 14 % higher than the standard), and phenylalanine (up to 4.2 g in the Sentyabrinka variety, which is 40 % higher than the standard). At the same time, a clear deficiency of methionine was revealed, the content of which in all analyzed varieties did not exceed 50% of the standard level, which emphasizes the need to continue breeding work to improve the amino acid profile of soybeans and increase its nutritional value. The results obtained are important for assessing the nutritional value of soybean varieties, their potential as a source of vegetable protein in the food industry and for creating functional food products. These studies can be useful for breeders, food manufacturers and nutritionists in developing more nutritious and healthy products based on this crop.