Effect of glucose oxidase, transglutaminase, and pentosanase on wheat proteins: Relationship with dough properties and bread-making quality

Glucose oxidase (Gox), transglutaminase (TG), and pentosanase (Pn) were investigated for their effect on bread quality. The changes introduced in wheat protein by the action of these enzymes were analysed to explain dough behaviour. Gox treatment decreased free sulphydryl groups (SHf), increased glutenin macropolymer contents, and modified the electrophoretic pattern of protein fractions. Gox modified mainly albumin, globulin, and glutenin, forming large protein aggregates. These modifications explained the high strength of the dough and the low bread specific volume of samples with Gox. TG treatment modified solubility in SDS of protein and decreased glutenin macropolymer content. However, it formed large protein aggregates. The new cross-linking bonds introduced by this enzyme were different to S–S bonds and, consequently, the dough was less extensible and showed high resistance. Pn treatment increased water soluble pentosan content. Moreover, in these samples a tendency to increase SHf content was observed. In addition, Pn increased protein solubility in isopropanol, which indicates that the reduction of pentosans size decreases steric impediment of insoluble pentosans, thus increasing interaction among protein and making their extraction easier. These changes at the microscopic level allowed explaining the formation of softer dough and the production of higher specific volume in breads with Pn.