Marinating and Salting of Herring, Nitrogen Compounds’ Changes in Flesh and Brine

Effect of technological factors on the activity and losses of cathepsins B, D and L during the marinating of Atlantic and Baltic herrings

“…This, in turn, results in the inhibition of peptide content increase after 4–7 days, which is accompanied by a successive increase in the content of free amino acids (FAA) and oligopeptides, as observed in previous studies . The high content and diversity of exopeptidases explain why the qualitative composition of PHP may determine the sensory quality of meat of the marinades to a greater extent than the quantitative composition . The third reason for the decrease in cathepsin D content in meat during marinating includes losses of cathepsins to brine, which was described in the section below “Proteolytic activity in marinating brine”.…”

“…Commonly cited studies carried out by Mayer provide only speculation on the importance of endogenous cathepsins and marginalize the influence of exogenous proteases released by bacteria in the ripening process of the meat of marinades. It is commonly believed today that endopeptidases (cathepsins B1, D, L and E) take part in the first stage of the ripening process and that the further course of this process is predominated by exopeptidases, like cathepsin A, B2 and C. This is confirmed by results of (i) the activity of cathepsins A and C against products of cathepsin D and (ii) a rapid increase in the content of proteins with a lower molecular weight and polypeptides only until day 3–4 of marinating, followed by a stable increase in the content of oligopeptides and free amino acids . Although some works describe investigations concerning the effect of freezing, salt concentration and pH value on the activity of cathepsins, they were conducted only on raw fish tissue or on purified enzymes .…”

“…Godiksen and Nielsen demonstrated the effect of a low pH value on the activation of the latent form of cathepsin L and inactivation of cathepsin B in a crude extract of herring. Therefore, a high concentration of acetic acid may inhibit and diminish the contribution of exopeptidases, which contributes to a decreased content of FAA and poorer sensory quality of the marinades …”

“…Today, studies on the marinating process are mainly based on analyses of nitrogen compounds in the meat tissue, which is, however, insufficient . Additional analyses of the marinating brine, used for fish marinating appear to be very helpful . Our previous study demonstrated, for the first time ever, the presence of aspartyl proteases, mainly cathepsins D, in the brine left after fish marinating .…”

Distribution of Cathepsin D Activity between Lysosomes and a Soluble Fraction of Marinating Brine

“…Losses of aspartyl and cysteine cathepsins diminish the proteolytic activity in the ripening meat. Lower activity of cathepsins contributes to deterioration of the quantitative and qualitative composition of PHB in semi‐marinades and in the end‐product (Szymczak and others ; Szymczak and others ; Szymczak ).…”