The squid (Loligo pealei) byproduct composed of heads, viscera, skin, fins, and small tubes was subjected to hydrolysis at 55 degrees C and natural pH (6.8) using endogenous proteases. Squid hydrolysate was characterized during the course of hydrolysis for changes in the degree of hydrolysis, viscosity, electrophoretic pattern of proteins and peptides, and amino acid and fatty acid profiles. The change in viscosity can be used to monitor the progress of protein hydrolysis up to the molecular mass of 26.63 kDa. The 2 h hydrolysis resulted in a 2-fold increase in the total free amino acids and yielded hydrolysate with protein molecular mass of < or =45 kDa having feed attractability and good amino acid and fatty acid profiles with high contents of essential amino acids and fatty acids. Such hydrolysis-induced changes can make squid byproduct hydrolysate a good source of aquaculture feed ingredient, especially for a starter diet for larval fish.

Effects of alginate, iota-carrageenan, soy protein concentrate (SPC), sodium tripolyphosphate (STPP), and sorbitol on physicochemical and sensory properties of red hake mince stored at -20°C for 17 wk were investigated. The addition of 0.4% alginate, 4% sorbitol, and 0.3% STPP kept the mince from hardening and improved its dispersibility during mixing. This is believed to be a result of reduced protein denaturation as evidenced by higher levels of water, salt, SDS-soluble proteins, and higher free sulfhydryl contents than the untreated control mince, which hardened with compact texture and exhibited considerable syneresis. Alginate appears to be responsible for preventing muscle fiber interaction through electrostatic repulsion and chelating Ca 2+ , thus improving dispersibility. Sorbitol and STPP with or without SPC and iota-carrageenan did not improve the dispersibility.

Transglutaminase (TGase)-treated skim milk powder (TG-SMP) was prepared by freeze-drying skim milk after TGase treatment (10 U/g milk protein, 40 °C for 3 h), followed by TGase inactivation at 85 °C for 5 min.TGase modification resulted in significant increases in hardness and water holding capacity (WHC) of heat-induced gels (10% protein, w/v). A marked increase in storage modulus (GЈ) of TG-SMP upon heating suggests that TG-SMP has a greater gelling ability than control-SMP (C-SMP) prepared with predenatured TGase. Acid gels prepared from TG-SMP had a significantly higher WHC at all solid levels (12%, 14%, and 16%) tested and formed a more elastic network than C-SMP.

Mechanical refining and cryostabilization methods have been developed to increase the commercial use of fish mince from the underutilized fish species.Freeze-induced texture hardening and drip loss in the white, lean fish mince, and rancidity in the dark, oily fish mince can be controlled by the use of appropriate cryoprotectant mixtures. 2-4% milk protein concentrate was effective in controlling rancidity and fishy odor developments in oily fish mince by binding low molecular weight reactive substances, while the combination of 2% soy protein concentrate and 0.4% alginate plus conventional cryoprotectants (4% sorbitol, 0.3% STPP) retarded fishy odor development and texture hardening in lean fish. Alginate helped maintain the dispersibility of fish mince by preventing muscle fiber interaction during frozen storage. Cryostabilization of fish mince enables the development of a variety of value-added mince-based seafood products formulated to provide desired flavor and texture.

Locally generated squid‐processing byproduct was processed into concentrated hydrolysate (22% solids, 17.3% protein, and 3.0% lipid, primarily phospholipids—11.6% eicosapentaenoic acid/24.5% docosahexaenoic acid on a lipid weight basis). Two microparticulate diets (65% protein, 19% lipid, 7.5% carbohydrate, and 19.12 MJ/kg energy, on a dry weight basis) were prepared using squid hydrolysate (SH) and squid‐herring hydrolysate as sole protein sources (73.3 and 78.65% of the whole diet, respectively). A 22‐d feeding trial with summer flounder, Paralichthys dentatus, larvae of 17 d after hatch showed that the survival rate (92%) of larvae fed SH was significantly (P < 0.05) higher than those of larvae fed live Artemia nauplii (81%) and a commercial diet, Proton (65%), while specific growth rates (SGR) were comparable (2.23% /d for SH and 2.86% /d for Artemia) with the lowest for Proton (1.39% /d). After switching from commercial and Artemia diets to a SH diet for 17 d following the 22‐d feeding, significant improvements were seen in survival rates of postweaning larvae fed previously commercial (65.28–76.57%) and Artemia diets (81.25–89.07%).