Impact of collagen degradation on the textural quality of salmon (Salmo salar): A preliminary study from the perspective of endogenous collagenase and bacteria

Salmon, as a globally popular seafood, undergoes protein degradation during storage, which affects its texture and flavor. This study investigated the factors causing collagen degradation in salmon and their impact on its textural quality by comparing the quality changes of salmon with or without collagenase inhibitor (T: taxifolin) and bacteriostatic inhibitor (P: Procline-300). To eliminate the impact of cysteine protease, the cathepsins inhibitor (E: E−64) were also added. The results indicated that an increase in the content of TCA-soluble peptides and total volatile base nitrogen (TVB-N) was inhibited by suppressing endogenous cathepsins, collagenases, and microorganisms. On the 7th day, the TCA-soluble peptides in both the ETP and EP groups (approximately 3.013 μmol tyrosine/g) were lower than that observed in the CK and ET groups (P < 0.05). The hardness of salmon meat in the ETP treatment group was respectively 17.78 %, 13.89 %, and 15.26 % higher than that of meats in the CK, ET, and EP groups (P < 0.05). This hardness and transverse relaxation time by low-field nuclear magnetic resonance indicated that the degradation of collagen had a negative impact on the water migration and textural properties of salmon muscle tissue. SDS-PAGE, principal component and correlation analyses suggested that the degradation of collagen was induced by both microorganisms and endogenous collagenases, and the effect of proteolytic activity derived from microorganisms was higher. This study provided new insights into the mechanisms of collagen degradation in salmon during storage and highlighted the importance of controlling microbial activity to maintain textural quality.