Process Scale-up for the Application of Fish Protein Isolate Obtained from Processing Co-products by Isoelectric Solubilization/Precipitation.

Salmon-processing co-products (fish frames containing bones, skin, and scales) were used to recover fish protein isolate (FPI) with isoelectric solubilization/precipitation (ISP) of protein at pH 12 and pH 5.5, respectively. Based on microbiological examination, FPI does not appear to present a microbiological safety concern. In fact, ISP may improve the microbial safety of FPI. In laboratory-scale experiments, different ratios of water and FPI (10:0, 10:1, 10:2, and 10:5; w:w) were used to prepare FPI-brine containing 15 or 20 g/100 ml of NaCl. The FPI brine was injected into salmon fillets before smoking. Based on laboratory-scale results, only a 10:5 ratio was tested at pilot scale in low- and high-quality fillets. Not only did the addition of FPI to brine increase (p < 0.05) the weight of smoked salmon, but it also reduced (p < 0.05) the number of injections and injection time by approximately 50%. FPI addition improved overall sensory quality at the laboratory scale but not at the pilot scale. FPI was also used as a partial replacement of salmon mechanically separated meat (MSM) in fish patties at a laboratory and pilot scale. The addition of up to 50% of FPI to fish patties in laboratory-scale experiments did not (p > 0.05) increase cook loss, but the texture was less acceptable due to their almost paste-like consistency and appearance. Adding up to 30% of FPI to fish patties in pilot-scale experiments resulted in lower (p < 0.05) cook losses and acceptable sensory quality. This study demonstrated that the advantages of FPI at the laboratory scale produced similar benefits at the pilot scale for seafood such as smoked fish and restructured products. The injectable FPI-brine and fish patties tested in this study at laboratory and pilot scales may be an advancement for commercial applications of FPI. [ABSTRACT FROM AUTHOR]