Abstract: In order to further explore flavor peptides and their structure-activity relationship, umami peptides from Yangjiang Douchi were separated and purified by successive alcohol precipitation method, ultrafiltration and ion exchange resin adsorption. The amino nitrogen content, succinic acid content, nucleotide content, relative molecular mass distribution of peptides and free amino acid composition of the obtained fractions were compared. In addition, sensory evaluation and electronic tongue were used to verify the taste characteristics of each fraction. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to identify the amino acid sequences of the best flavor peptides. The results showed that among the fractions obtained alcohol precipitation and ultrafiltration (E1, E2, E3, E4, A1, A2 and A3), E3 and A3 were the best ones in terms of umami. Fraction A3-I, which was obtained after purification using XAD-7 ion exchange resin, had the strongest umami taste with an umami value of 7.65. Finally, through identification and molecular docking screening, the peptide sequence with the best umami taste was found to be TYDGDTEP. This study provides a theoretical basis and reference for the separation of flavor peptides from Douchi and further exploration of its flavor pattern.

Key words: Douchi; flavor peptides; isolation and purification; taste characteristics; peptide identification