Extraction, Identification, and Virtual Screening of Sweet Peptides and Umami Peptides from Chicken Meat of Chahua Chicken No.2

In order to investigate sweet and umami peptides of Chahua Chicken No.2, this experiment was carried out to isolate and purify the best-tasting fraction F1 from the aqueous extract of Chahua Chicken No.2 by using a combination of ultrafiltration, gel filtration chromatography and sensory evaluation. The F1 fraction was subjected to amino acid determination and the peptides were identified by Liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, virtual screening methods such as peptide scoring, machine learning, and active fragment prediction were used to screen potential sweet and umami peptides and to analyze their precursor proteins. The results showed that four fractions (F1, F2, F3 and F4) were obtained by isolation and purification, among which the F1 fraction was the strongest flavor, with total sweet, umami and bitter amino acids of 12.47, 8.36 and 4.19 mg/g, respectively. A total of 2006 peptides were identified in the F1 fraction, and the virtual screening yielded seven potential sweet peptides (PDPP, PKPP, PLKPP, LPEPP, APPRMPP, GPPVSGPP, PPPEEKPRIK) and five potential umami peptides (VEK, EEA, EELL, VVEA, VEELMKGQED). These peptides were all less than or equal to 10 in length, molecular weights ranging from 347.13 to 1189.68 Da, with flavor-presenting activity related to amino acid composition. Potentially sweet peptides were mainly derived from Titin, histone H3-lysine (4) N-methyltransferase, and umami peptides were mainly derived from Titin. This study provides a theoretical basis for the improvement of the characteristic flavor system of Chicken No.2, as well as a basis for the in-depth development of local chicken resources and sweet peptide and umami peptide products.