Project Number: 6054-43440-049-05-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 30, 2014
End Date: Aug 1, 2019
The first objective is to make catfish skin hydrolysates that contain bioactive peptides using food grade proteases based on results from our previous USDA ARS SRC funded study. Physical, chemical, antioxidant capacity and other functional properties of the hydrolysates will be determined. The second objective is to purify and isolate the bioactive peptides using ultrafiltration, gel filtration, and high performance liquid chromatography and characterize the peptides of interest using mass spectrometry.
Fish species are good sources of high quality protein and there are opportunities to use more fish processing byproducts as protein ingredients in foods, feeds, and industrial applications. There is little utilization of fish skin protein as a functional ingredient in the food industry. Skin from Channel catfish (Ictalurus punctatus) is an abundant and underutilized byproduct that can be used as a unique protein source to make hydrolysates. Hydrolysates made from fish skin contain bioactive peptides and our previous study has shown that fish skin hydrolysates have unique functional properties. Peptides sequences that may have valuable bioactive properties, such as antioxidant and antimicrobial properties from catfish skin protein hydrolysates produced with proteolytic enzymes can be produced and isolated. Researchers have reported that a peptide sequences that have antioxidant properties generally contains 3–16 amino acid residues. They have reported that the antioxidant activity of a peptide sequence is related to composition, structure and correct positioning in the peptide sequence. In the proposed study, catfish skin will be hydrolyzed with proteases to obtain antioxidant peptides. The peptides will be purified with gel filtration and chromatography and selected peptides sequenced and characterized. The peptides may have potential commercial application; for example they can be applied to extend the shelf life of seafood and meat products. Experimental Design Fresh catfish skin will be supplied by USDA/ARS Southern Regional Research Center collaborators.. Catfish skin hydrolysates will be produced and characterized at the pilot plant located in the Louisiana State University Agricultural Center, Baton Rouge, Louisiana. The hydrolysates will be fractionated based on molecular size through an ultrafiltration membrane system with a molecular weight cut off (MWCO) of 10 kDa. Both fractions with molecular weight distributions of greater than 10 kDa and less than 10 kDa will be freeze-dried. The antioxidant activity and possibly antimicrobial activity of fractions will be determined. A gel filtration column will be used to further separate the low molecular weight peptide fractions. Peptides will be isolated using a high performance liquid chromatography (HPLC). The peptides after HPLC purification will be analyzed for amino acid sequence and molecular mass determination by using a mass spectrometer. Peptides isolation and sequences analysis will be conducted at the USDA ARS SRRC in New Orleans. Statistical significance of observed differences among means of experimental results will be evaluated by Analysis of Variance (ANOVA) (SAS Version 8.2, SAS Institute Inc., Cary, NC.), followed by post-hoc Tukey’s test.