Properties of Pollock (theragra Chalcogramma) Skin Hydrolysates and Effects on Lipid Oxidation of Skinless Pink Salmon (oncorhynchus Gorbuscha) Fillets during 4 Months of Frozen Storage

Fresh pollock skin was hydrolyzed for 10 min (PPH10), 30 min (PPH30) and 45 min (PPH45), and the chemical and functional properties of pollock skin protein hydrolysates were evaluated. PPH45 (79.6%) had significantly higher nitrogen solubility values than PPH30 (72.6%) and PPH10 (64.8%). Emulsifying stability values for PPH10 and PPH30 were significantly higher (P < 0.05) than PPH45. Fat adsorption values for PPH45 (4.7 mL oil/g protein) were greater (P < 0.05) than PPH10 (3.6 mL oil/g protein) and PPH30 (3.7 mL oil/g protein). Salmon fillets stored frozen for 4 months including those glazed with pollock skin protein hydrolysate, water and glycerin solutions had increased yield and thaw yield values when compared to the nonglazed (NG) control fillets. Thiobarbituric acid (mg malondialdehyde/kg sample) values from fillets coated with a solution containing PPH10 (0.8) and stored frozen for 4 months were significantly lower (P < 0.05) than other glazed and NG fillets. PRACTICAL APPLICATIONS Pollock skin is an abundant and underutilized resource that can be used as a unique protein source to make fish protein hydrolysates. Utilizing proteolytic 3 Corresponding author. Department of Food Science, 111 Food Science Building, Louisiana State University Agricultural Center, Baton Rouge, LA 70803. TEL: (907) 486-1535; FAX: (225) 5782300; EMAIL: [email protected] Journal of Food Biochemistry 32 (2008) 247–263. All Rights Reserved. © 2008, University of Alaska Fairbanks Journal compilation © 2008, Blackwell Publishing 247 enzymes, pollock skin protein hydrolysates (PPHs) can be prepared that have new and/or improved chemical and functional properties. The natural antioxidant and water-soluble properties and film-forming ability of PPHs make it ideal for coating material to suppress lipid oxidation in fish fillets during frozen storage. Edible coatings prepared from pollock skin hydrolysates have potential applications for enhancing the storage stability and quality of frozen fillets. The edible hydrolysate coating may also provide some degree of protection against damage during transportation and handling of fish fillets.