Functional properties of low Mr wheat proteins. III. Effects on composition of the glutenin macropolymer during dough mixing and resting

The effect of low Mr wheat protein addition on the amount and composition of the glutenin macropolymer (GMP) of dough was investigated for the three wheat cultivars Obelisk (weak), Camp Remy (medium strong) and Rektor (strong). During mixing, the amounts of high and low Mr glutenin subunit classes, and of the individual subunits decreased. The proportion of high Mr glutenin subunits decreased and that of low Mr glutenin subunits increased, indicating an inhomogeneous distribution of the two subunit classes within the polymers present in GMP. During resting, the amounts of the glutenin subunit classes and of individual subunits increased. Meanwhile, the proportion of high Mr glutenin subunits in GMP increased. Low Mr wheat protein addition retarded re-polymerisation in that the amounts of glutenin subunit classes and of individual high Mr glutenin subunits in GMP increased less than without addition. The proportion of high Mr glutenin subunits in GMP directly after mixing was also decreased by low Mr wheat protein addition, and the proportion increased faster during dough resting, compared with the GMP in dough without low Mr wheat protein addition. Eventually, after 90 or 135 min resting, no differences existed in the proportions in GMP from doughs with and without low Mr wheat protein addition. Low Mr wheat protein addition had no specific effect on individual high Mr glutenin subunits, nor on the x-type/y-type subunit ratio in the GMP. In contrast, with increasing low Mr wheat protein addition, a highly significant reduction in the subunit 10 or 12/subunit 9 ratio in GMP was observed. This finding is in line with the decrease in this ratio directly after mixing in GMP of the dough without low Mr wheat protein addition. Since no specific effects were observed, it can be concluded that the low Mr wheat protein acts rather unspecifically on the GMP of dough. © 1997 Academic Press Limited.