Functionality of whey and casein in fermentation and in breadbaking by fixed and optimized procedures.

Abstract

The effects of 4% dairy ingredients on dough absorption and mixing time, parameters of fermentation, loaf volume, and bread characteristics were determined. Dairy ingredients, generally, increased water absorption and decreased mixing time. The decrease in mixing time was to some extent reversed by heat treatment (at 80 or 95°C) of nonfat dry milk (NFDM), casein, or whey. Dialysis of whey did not improve its poor mixing stability. Untreated dairy ingredients lowered the dough height at maximum development time (H m , measured by the Rheofermentometer). The drop was reversed by heat treatment or dialysis. H m was positively correlated (r = 0.87) with time of H m (T 1 ) and negatively correlated (r = -0.88) with drop in volume after 2 hr. Caseins drastically reduced the loaf volume of bread baked in the bread machine ; heat treatment of the caseins counteracted the loss. Heat-treated acid whey protein increased the loaf volume and lowered the rate of staling, as measured by universal testing machine (UTM) crumb firmness measurements and differential scanning calorimetry enthalpy changes. In bread baked by the optimized procedure, heat treatment alone, or in combination with dialysis, counteracted the deleterious effects of adding nontreated whey protein, but not of caseins. Baking performance could be predicted by the Rheofermentometer time of maximum gas formation. Heat-treated whey proteins lowered the rate of staling in optimally baked bread as in bread baked by the fixed formula.