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Title: Rheological and Functional Properties of Catfish Skin Protein Hydrolysates

Author
item YIN, H - Louisiana State University
item PU, J - Louisiana State University
item WAN, Y - Louisiana State University
item XIANG, B - Louisiana State University
item Bechtel, Peter
item SATHIVEL, S - Louisiana State University

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2009
Publication Date: 1/20/2010
Citation: Yin, H., Pu, J., Wan, Y., Xiang, B., Bechtel, P.J., Sathivel, S. 2010. Rheological and Functional Properties of Catfish Skin Protein Hydrolysates. Journal of Food Science. 75(1):E11-E17.

Interpretive Summary: Catfish is composed of about 32% of fillets and other parts (skin, head, frame, and viscera) are usually discarded or processed into fish meal. Catfish skin constitutes about 6.3% of whole catfish. Protein hydrolysis can be used to improve or modify the properties of proteins and catfish skin can be used as a unique protein source to make fish skin hydrolysates. The objectives of this study were to isolating soluble and insoluble proteins from hydrolyzed catfish skin and study the chemical and functional properties of the protein hydrolysates. Catfish skin was hydrolyzed and the soluble and insoluble fractions separated and the physical and chemical properties evaluated. Results from this study identify opportunities for development of value-added -protein products from under catfish skin.

Technical Abstract: Catfish skin is an abundant and underutilized resource that can be used as a unique protein source to make fish skin hydrolysates. The objectives of this study were to: isolating soluble and insoluble proteins from hydrolyzed catfish skin and study the chemical and functional properties of the protein hydrolysates and evaluate the properties of emulsions made from the protein powders Freeze-dried catfish skin soluble (CSSH) and insoluble hydrolysate (CSISH) powders were analyzed for proximate analysis, emulsion stability, fat absorption, amino acids, color, and rheological properties. CSSH had significantly higher protein, ash, and moisture content but lower fat content than that of CSISH. The yield of CSSH (21.5±2.2%) was higher than that of CSISH (3.0±0.3%). CSISH had higher emulsion stability than CSSH. CSSH was light yellow in color and CSISH was darker. The mean flow index values for emulsion containing CSSH and CSISH were both less than 1.0, which indicated that they were both pseudoplastic fluid. The G’ and G’’ values for the CSISH emulsion were higher than those of CSSH emulsion, which indicated that the viscoelastic characteristic of the CSISH containing emulsion was greater than the CSSH containing emulsion. The study demonstrated the CSSH and CSISH had good functional and rheological properties. They have potential uses as functional food ingredients.