ENZYME-MODIFIED PROTEINS FROM CORN GLUTEN MEAL - PREPARATION AND FUNCTIONAL-PROPERTIES

Functional properties of proteins in corn gluten meal (CGM) can be improved by enzyme hydrolysis combined with membrane technology. CGM was treated with a protease (Alcalase), resulting in 30-50% of the proteins being converted to soluble peptides. Conversions were higher when CGM was pretreated with cysteine or sulfite. Solubility and clarity of the enzyme-modified proteins were better at higher degrees of hydrolysis (DH). Higher DH increased initial foam volume but decreased foam stability. Membrane filtration of the hydrolyzed CGM reaction mixture resulted in two peptide fractions, as determined by size-exclusion high-performance liquid chromatography. Protein solubility of the membrane-permeable fraction was 90-99% compared with 8% for unmodified proteins. Larger-pore membranes improved foaming but decreased solubility and clarity. Moisture sorption at a water activity of 0.97 was 3.75 g water per gram of enzyme-modified/ultra-filtered CGM, compared with 0.2 g/g for the unmodified CGM.