Application of a crude digestive proteases preparation to improve the ripening of marinated fillets from low‐technological value Baltic herring (Clupea harengus membras L.).

BACKGROUND: As a result of climate change (reduced the oxygen content and food available in the waters) and overfishing, ever larger batches of the herring catch are classified as low‐value fish and used for feedstuff or canned food production. Fast and complete ripening of marinated fillets, especially from low‐value Baltic herring, poses a problem because of the low muscle protease activity and changes in muscle tissue proteins. RESULTS: For the first time, a crude digestive proteases preparation (CDPP) was obtained from herring viscera using a two‐stage method consisting of ethanol extraction and then salt precipitation. CDPP had a reduced hemoglobin content, with optimum activity at pH 7.5–8.8 or 60–120 g kg−1 NaCl. At pH 4–5, it still exhibited 24–68% of proteolytic activity. CDPP was used for 4–24 h of brining of fresh and frozen–thawed fillets or injection of fresh fillets before marinating. CDPP‐brining increased especially cathepsin D and carboxypeptidase A activities, whereas it decreased cathepsin B and L activities in the marinades. CDPP‐brining mitigated the negative effect of freezing–thawing on mass‐yield, protease activity, protein hydrolysis, texture profile, colour and sensory quality of the marinated fillets. CDPP‐injection was found to be the best method because it increased mass‐yield and ripeness of the marinated fillets to a greater extent than CDPP‐brining did. The marinades from the CDPP‐treated fillets had no bitter taste as a result of the presence of hemoglobin or chymotrypsin, and there were no results indicating lipid oxidation. CONCLUSION: The application of CDPP in marinating technology is a viable approach to enable the use of low‐value herring in food production, shorten the marinating time, and improve the ripeness and sensory quality of meat. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]