Glucose oxidase (GOX) has been recognized as an alternative to substitute chemical oxidants in bread making, however the action exerted on wheat flour proteins by the $H_2O_2$ produced is still unclear. Looking for a better understanding of the role of GOX and $H_2O_2$ in the bread making process, the effect of varying GOX levels and mixing time on soluble and insoluble wheat flour protein fractions was studied. Results showed that GOX promoted a decrement in free SH groups in both proteins, being the most evident effect on the soluble fraction at the beginning of the mixing process, remaining almost constant afterwards. $H_2O_2$ was continuously produced during mixing, showing its largest consumption during the first 6 min without significant SH changes afterwards. Results suggest that $H_2O_2$ must be involved in other reactions as it remains in the sample; this also suggests that oxygen is not a limiting factor in this reaction.