EFFECTS OF ENZYMES AND OXIDIZING-AGENTS ON SHEAR-STRESS RELAXATION OFWHEAT-FLOUR DOUGH - ADDITIONS OF PROTEASE, GLUCOSE-OXIDASE, ASCORBIC-ACID, AND POTASSIUM BROMATE

Measuring shear stress relaxation with an established research rheomet er after slowly applying large strain proved useful for characterizing the effects of different chemical and enzymatic additives. Baking tes ts done with and without added ascorbic acid indicated that the method can be used for predicting effects of such additives on breadbaking q uality. The relaxation process for dough is discussed in terms of two flow processes, one occurring at short time periods and the ether at l onger time periods. The slowly applied large strain shear stress relax ation method provides information about stress relaxation behavior dur ing the second flow process. The effects of two enzymes (protease and glucose oxidase) and two chemical additives (ascorbic acid and potassi um bromate) were studied. The results are presented as the stress rela xation curve with the corresponding rate plot and the initial value of the stress. Addition of the oxidizing agents increased the second flo w process times and decreased the relaxation rate during the second pr ocess. Protease shortened the second flow process times and increased the relaxation rate during the second process. Glucose oxidase separat ed the two flow processes by increasing the relaxation time of the sec ond process and decreasing the relaxation time of the first process.