Protein extraction pH and cross-linking affect physicochemical and textural properties of protein gels made from Channel catfish by-products.

Abstract

BACKGROUND\nChannel catfish farming is very important aquaculture in the Southern states of United State. However, huge amounts of by-products are generated from catfish fillet processing industries. The by-products (mostly heads and bone frames) are excellent sources of proteins. Currently, catfish by-product has little value, and is regarded as a waste , which if not utilized properly would cause serious environmental pollution. Therefore, to find a way to utilize those by-products is critical for the economy of aquaculture.\n\n\nMETHOD\nProtein isolates were extracted from the mixture of catfish by-products (heads and frames) with different alkaline conditions (pH 7.5-11) and made into protein gels. Secondary structures of extracted protein isolates were studied. Microbial transglutaminase (MTGase, 0-4 U/g of proteins) was incorporated to improve gel structure. Gelling, physicochemical, textural and thermal properties of protein gels treated with/without MTGase were investigated. Protein pattern changes of MTGase treated protein gels were studied and the microstructures of protein gels were analyzed.\n\n\nRESULTS\nAlpha-helicity of protein isolates made at pH 11 was 21.5% lower than that extracted at pH 8.5. Storage modulus (G ) of protein gel decreased with the increasing in extraction pH (pH >\u20099) of the corresponding protein isolate. MTGase treatment exhibited significant effect on denaturation temperature and enthalpy of protein gels. Excessive MTGase (>\u20092 U/g) could weaken the gel structure.\n\n\nCONCLUSION\nProtein isolates can be extracted from catfish by-products and made into protein gels which is a value-added product. This article is protected by copyright. All rights reserved.