Determination of protein peptide content in edible Jiaosu

ObjectiveThis study aimed to establish a method to determine the content of peptides in edible Jiaosu accurately.MethodsAfter the sample was precipitated with a certain concentration of trichloroacetic acid (TCA) to remove protein macromolecules, the total hydrolyzed amino acid content and free amino acid content in the sample were determined by amino acid analyzer according to the two national standards GB 5009.124—2016 and GB/T 30987—2020 respectively. The peptide content is calculated by the difference between the two. For samples containing collagen protein in raw materials, refer to the first method of GB/T 30987, that is, the sulfonic acid type cation exchange lithium column and the corresponding mobile phase gradient and other chromatological conditions, to determine the 17 hydrolyzed amino acid content and free amino acid content including hydroxyproline and their total content in the sample.ResultsIn the range of 0.005~0.250 μmol/mL, the linear correlation coefficients (r) between the peak areas of 17 amino acids and their corresponding amino acid concentrations were greater than 0.999. The recoveries of all hydrolyzed amino acids and free amino acids were in the range of 95.1%~102.2%, and the relative standard deviations (RSD) were less than 5.39%.ConclusionThe method is simple, accurate and reproducible, and is suitable for the determination of peptide content in edible Jiaosu samples.