The effect of previous storage condition on the diffusion and contribution of digestive proteases in the ripening of marinated Baltic herring (Clupea harengus)

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

“…After CDPP-brining or CDPP-injection, the fillets were placed in buckets with a marinating brine (45 g kg −1 acetic acid and 60 g kg −1 sodium chloride) in a ratio of 1.0:1.5 (w:w) obtaining FB-M, TB-M and FI-M samples. Fillets were marinated for 5 days at 7 °C according to Kamiński et al, 8,9 after which they were separated from the brine, weighed and subjected to analyses. The control samples were fresh or frozen-thawed marinated fillets without CDPP pre-treatments (time 0 in figures).…”

“…Digestive proteases extracts were made from intestines, fresh and CDPP-treated herring meat using water (1:10, v:w) and from marinated fillets using Tris-HCl 150 mM buffer at pH 7.8. 8,9 Cathepsins from raw material and marinated fillets were extracted with ultrapure water. The obtained homogenates were centrifuged at 20 000 × g for 10 min at 4 °C to obtain the work extract determined for the activities of digestive proteases and cathepsins.…”

“…Amidase trypsin (Am-Tr) was measured at pH 8.2 against N-benzoyl-DL-arginine (BApNA); esterase trypsin (Es-Tr) at pH 8.2 against N⊍-p-tosyl-L-arginine methyl ester hydrochloride, chymotrypsin at pH 7.8 against N-benzoyl-L-tyrosine ethyl ester; and carboxypeptidase A (Cp-A) at pH 7.5 against 4-methoxyphenylazoformyl-Phe. 8,9 The activity of cathepsin B against Z-RR-MCA, cathepsin D against Mca-GKPILFFRLK(Dnp)-r-NH2 with and without pepstatin-A, and cathepsin L against Z-FR-MCA were determined according to Szymczak. 7 Protease activity assays were performed at 37 °C using continuous spectrophotometric rate determination and units of enzyme activity were converted per 1 g of tissue.…”

“…2 Recent studies have shown that herring caught after spawning and during feeding can be pre-proteolyzed with endogenous digestive enzymes with the intendion of complete ripening using traditional marinating. 8,9 The disadvantage of these methods includes the excessive diffusion of chymotrypsin and hemoglobin (Hb), which increase the bitter taste and the brown colour of the meat. Furthermore, Hb is the main prooxidant of unsaturated fatty acids in fish.…”

“…The results of previous studies have shown that the use of digestive proteases complemented the low activity of cathepsins during the marinating of low-value herring, but the main problem was too much Hb diffusion. 8,9 Therefore, the present study aimed to develop a cheap method for producing a crude preparation of digestive proteases with high proteolytic activity and allowing the elimination of as much Hb as possible, and then subsequently develop a method enabling the use of this preparation in marinating technology. The global idea was to develop a new technology for the production of marinades from low-value herring, which would enable greater use of marine raw materials for high-value foods.…”