Submitted to: Journal of Food Biochemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/6/2008
Publication Date: 4/1/2008
Citation: Sathivel, S., Huang, J., Bechtel, P.J. 2008. 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. Journal of Food Biochemistry. 32:247-263. Interpretive Summary: Pollock skin protein hydrolysates contain natural antioxidants and have the ability to form films. These properties make fish skin hydrolysates candidates for use as coating material to suppress lipid oxidation in fish fillets during frozen storage. The objectives of this study were to determine the properties of pollock skin protein hydrolysates and to evaluate the effectiveness of coatings made with hydrolysates on the quality of skinless pink salmon fillets during frozen storage. Three pollock skin hydrolysates were made by hydrolyzing the skins for 10, 30 or 45 minutes. Glazed fillets had a higher yield and thaw yield than non-glazed salmon fillets. Lipid oxidation was reduced after 4 months of frozen storage in fillets coated with a solution containing hydrolysate made from skin that had been hydrolyzed for 10 min. Pollock skin hydrolysates have many desirable properties, including emulsifying stability and fat absorption capacity, which support the use as natural food ingredients.
Technical Abstract: 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. The degree of hydrolysis (%) after 10, 30, and 45 min of hydrolysis was 15%, 28%, and 36%, respectively. All pollock hydrolysates met essential amino acid requirements for adults. 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 frozed for 4 months including those glazed with PPH, water and glycerin solutions had increased yield and thaw yield values when compared to the non glazed control fillets. TBA (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 non glazed fillets.