Protein Distribution in Gluten Products Isolated During and After Wet‐Milling of Maize Grains

Abstract

ABSTRACT The protein distribution in five gluten samples isolated during and after wet‐milling of maize grains (slurry before and after filtration, total industrial gluten meal, and coarse and fine fractions obtained after sieving) was investigated by sequential extraction. Six fractions (FI‐FVI), including residue, were isolated. Heating filtered slurry to draw water away did not alter protein distribution. Compared with values reported in the literature for endosperm protein, we found a decrease in FI and FIV, respectively, extracted with salt alone and with reductant, due to proteolysis and partial elimination of nonprotein nitrogen during slurry filtration, and an increase in FII and decrease in FIII, alcohol‐soluble proteins extracted without and with reductant, respectively, due to the presence of SO 2 in the steeping liquor. Gluten, with respect to the endosperm from which it originated, was richer in zeins (FII + FIII) and glutelins (FV + FVI) due to partial removal of salt‐soluble proteins (FI + FIV) during the isolation process.