Abstract: Collagen tripeptides were prepared from frozen wet skin and dried scales of tilapia, and their physicochemical properties and storage characteristics at different temperatures were analyzed and studied using an electronic tongue and an electronic nose. The results showed that the contents of hydroxyproline and total nitrogen of fish scale collagen tripeptides were significantly higher than those of fish skin collagen tripeptides (P < 0.05). The proportion of molecular mass < 500 Da was significantly higher in fish skin collagen tripeptides than in fish scale collagen tripeptides (P < 0.05). During storage, the two collagen tripeptides showed no significant changes in the contents of moisture, total nitrogen or hydroxyproline, and their molecular mass distribution and tripeptide content remained relatively stable. Neither collagen tripeptides showed any significant changes in particle state during storage, and both reconstituted solutions were clear and transparent. Fish scale collagen tripeptides exhibited a saltier and bitterer taste compared with fish skin collagen tripeptides. The whiteness of fish skin collagen tripeptides decreased significantly when stored at 37 ℃, and the sensory score for color was the lowest after 3 months. The results of electronic tongue and electronic nose showed that the main taste attributes (umami, saltiness, and bitterness) and odor response values of both collagen tripeptides remained basically unchanged during storage, and they were clearly discriminated. There were no significant changes in the amino acid composition of fish scale collagen tripeptides during storage, while the Pro and Asp contents of fish skin collagen tripeptides increased significantly (P < 0.05) after storage at 37 ℃ for 3 months. The scavenging capacity of fish scale collagen tripeptides against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation were significantly higher than that of fish skin collagen tripeptides (P < 0.05), indicating better antioxidant activity. In addition, the ABTS radical cation activity of fish scale collagen tripeptides did not conspicuously change after simulated gastrointestinal digestion, while that of fish skin collagen tripeptides significantly decreased (P < 0.05). In conclusion, the two collagen tripeptides differed in physicochemical properties, and fish scale collagen tripeptides exhibited better storage stability. This study provides a theoretical basis for fully utilizing the by-products of tilapia processing to develop high-value collagen tripeptide products.

Key words: tilapia; collagen tripeptide; electronic tongue and electronic nose; molecular mass distribution; amino acid composition; antioxidant activity; storage stability