Five cuts from herring (Clupea harengus): Comparison of nutritional and chemical composition between co-product fractions and fillets

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.

Protein Hydrolysates from Fishery Processing By-Products: Production, Characteristics, Food Applications, and Challenges

Fish processing by-products such as frames, trimmings, and viscera of commercial fish species are rich in proteins. Thus, they could potentially be an economical source of proteins that may be used to obtain bioactive peptides and functional protein hydrolysates for the food and nutraceutical industries. The structure, composition, and biological activities of peptides and hydrolysates depend on the freshness and the actual composition of the material. Peptides isolated from fishery by-products showed antioxidant activity. Changes in hydrolysis parameters changed the sequence and properties of the peptides and determined their physiological functions. The optimization of the value of such peptides and the production costs must be considered for each particular source of marine by-products and for their specific food applications. This review will discuss the functional properties of fishery by-products prepared using hydrolysis and their potential food applications. It also reviews the structure-activity relationships of the antioxidant activity of peptides as well as challenges to the use of fishery by-products for protein hydrolysate production.

Pilot-Scale Antioxidant Dipping of Herring (Clupea harengus) Co-products to Allow Their Upgrading to a High-Quality Mince for Food Production

To enable production of high-quality mince from herring backbones, a scalable antioxidant strategy is needed due to the high susceptibility of herring muscle to lipid oxidation. We here measured the stabilizing effect of lab-/pilot-scale predipping of herring backbones (30-500 kg) in antioxidant solutions prior to production of mechanically separated mince (MSM). The antioxidants were (i) Duralox MANC, a mixture of rosemary extract, ascorbic acid, α-tocopherol, and citric acid, and (ii) rosemary extract with or without isoascorbic acid. Delivery of the key rosemary-derived antioxidant components carnosol and carnosic acid was monitored during the dipping process and ice/frozen storage. Predipping in 2% Duralox MANC gave MSM with 26.7-31.7 mg/kg carnosol + carnosic acid and extended the oxidation lag phase from <1 to 12 days during ice storage and from <1 to 6 months during frozen storage compared to control. Dipping in 0.2% rosemary extract with or without 0.5% isoascorbic acid solution gave MSM with 20.6-28.2 mg/kg carnosol + carnosic acid and extended the lag phase to 6 days and 9 months during ice and frozen storage, respectively. Our results confirmed, in pilot scale, that predipping herring coproducts in antioxidant solutions is a promising strategy to utilize these raw materials for, e.g., mince and burger production rather than for low value products as fish meal.