Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2006
Publication Date: 12/29/2006
Citation: Clare, D.A., Gharst, G., Sanders, T.H. 2006. Transglutaminase Polymerization of Peanut Proteins. Journal of Agricultural and Food Chemistry 55(2): 432-438. Interpretive Summary: With the advent of oil concerns in the U.S. the potential use of peanuts as a biodiesel source would result in a critical need for the development of innovative strategies that promote new usages of the protein fraction within the food industry high. This study is part of initial research to characterize and examine peanut protein for value added use. Previous work has demonstrated that a microbial enzyme, called transglutaminase, can cause the connecting of various proteins and sugars resulting in proteins with very different functional properties. We examined the effect of that enzyme on peanut protein in various raw and roasted forms and found that it modified the viscosity of peanut protein. Ultimately, we anticipate that these approaches will afford increased utility for peanut proteins by expanding its functional effectiveness within a given food product as previously demonstrated in other protein-based nutritional systems.
Technical Abstract: Transglutaminase promotes protein crosslinking reactions through an acyl transferase mechanism involving protein-bound glutaminyl residues and primary amines including the '-amino group of lysine residues in soy, myosin, gluten, oat globulin, casein and whey. Herein, we present a first report of transglutaminase catalysis of several peanut protein fractions, including purified Ara h 1. In most cases, SDS-PAGE banding patterns revealed the formation of high molecular weight polymers while catalysis of Ara h 1 resulted in distinct dimer formation. Crosslinking effects were accomplished in the presence and absence of the reducing reagent, dithiothreitol. Ortho-phthaldialdehyde assays, used to quantify the degree of polymerization, indicated ~30% coupling using either cold hexane extracted peanut protein fractions or lightly roasted flour dispersions. Rheological measurements established that transglutaminase-modified peanut extracts exhibited lowered viscosity readings compared to non-treated dispersions. Peanut protein polymers and glycoprotein conjugates, created by covalent linkage between protein substrates and monosaccharide amino sugars, exhibited equivalent IgE binding activity, compared to control solutions. These results suggested that potential allergic responses were not enhanced after enzymatic modification. Ultimately, these approaches may provide novel peanut-based food ingredients with unique functional characteristics for expanded applications within the world marketplace.