Production and assessment of Pacific hake (Merluccius productus) hydrolysates as cryoprotectants for frozen fish mince

- Pacific hake was hydrolyzed with 1% Flavourzyme for 1 h without adjusting pH.
- Fish protein hydrolysates (FPH) were effective cryoprotectants for minced fish.
- FPH minimized cook loss and expressible moisture of freeze/thawed fish.
- Differential scanning calorimetry showed that FPH stabilized fish myosin.
- Stronger sensory attributes were perceived in fish balls containing FPH.

The aim of this study was to investigate application of fish protein hydrolysates (FPHs) as cryoprotectants for cod fish mince subjected to freeze-thaw abuse. Response surface methodology revealed little difference in cryoprotectant ability between FPHs produced from Pacific hake muscle within the range of conditions studied, namely Flavourzyme® enzyme/substrate ratio (E/S 1-4%), time (1-6 h) and pH (5-7). When added at 4% or higher concentrations, FPH minimized expressible moisture and cook loss, while maximizing salt extractable protein from freeze-thaw abused fish mince, providing similar or better cryoprotection compared to an 8% sucrose-sorbitol blend, and a stabilizing effect of FPH on myosin was observed by differential scanning calorimetry. Sensory evaluation showed that addition of 8% FPH in fish ball products increased the perception of fishiness, saltiness, bitterness and firmness while decreasing moistness. FPH could be a viable alternative to the sugar-based cryoprotectants currently used for frozen fish products.