Biological Protein Value of Pteridium aquilinum (L.) Kuhn

Contemporary human diet is poor in proteins. Therefore, the modern food science should find new sources of high-grade protein. The bracken fern is rich in proteins can be an unconventional solution to this problem. The research objective was to study the protein contents of Pteridium aquilinum (L.) Kuhn, which grows on the territory of the Krasnoyarsk Region. The study featured Pteridium aquilinum (L.) Kuhn harvested in several districts of the Kozulka, Kuragino and Shushenskoye districts Krasnoyarsk Region in May 2021. Spectrophotometry and chromatography were used to assess the proteins and amino acids, respectively. The protein content in the dried fern samples ranged from 24 to 27%. All the samples contained fifteen amino acids, including seven essential ones, mostly represented by phenylalanine+tyrosine (2.17 g/100 g of protein). Glutamine was the dominating essential amino acid (4.98 g/100 g of protein). The score of all the essential amino acids was more than 100%. The limiting amino acid was represented by methionine+cystine. From the total of fifteen amino acids, twelve belonged to various classes of aliphatic amino acids, one – to aromatic amino acids, and two – to heterocyclic amino acids. In terms of biological value, the samples collected in the Kuragino district surpassed those from the Kozulka and Shushenskoye districts because they had a lower value of amino acid score difference coefficient (78) and the highest value of coefficient of amino acid utility (0.55). The index of essential amino acids for all the fresh fern samples ranged from 1.04 to 1.1, which indicates a greater value of the total of essential amino acids than in the reference protein. The qualitative and quantitative composition of amino acids of the bracken fern in the Krasnoyarsk Region showed that it can be used in food industry as an additional source of protein.