Factors influencing gelation properties of corn germ proteins

BACKGROUND: As a by-product of the oil industry, corn germ meal is mainly applied as a high-protein ingredient in animal feeds, without any application of the specific functional properties of corn germ protein (CGP). Factors influencing the gelation properties of CGP in relation to its dynamic rheology are still unclear owing to limited information. RESULTS: CGP concentrate was recovered by the isoelectric precipitation method, and factors affecting its gelation properties were investigated using a rheometer. A weak gel formed at natural pH with 0.3 mol L-1 NaCl, and the minimum gel-forming concentration was observed at 150 g kg(-1). Higher CGP protein concentrations induced stiffer gels, and linear relationships were found between protein concentration and gel stiffness (G') as well as between protein concentration and gel viscosity (G ''). Lower heating and cooling rate promoted the formation of stiffer gels. CGP gelation was both NaCl-and pH-dependent. Sodium tripolyphosphate significantly increased gel stiffness with increasing concentration. No difference in gel elasticity (tan delta) was observed with the inclusion of various concentrations of sodium tripolyphosphate or sodium polyphosphate. CONCLUSION: Heating and cooling rate, NaCl, protein concentration, pH and phosphates all impact the gel-forming ability of CGP concentrate. Desired gel properties can be obtained through adjustment of these factors. (C) 2017 Society of Chemical Industry