The subject of this research project was assessment of direct starch to ethanol conversion process course
of waste wheat-rye bread using granular starch hydrolyzing enzyme (GSHE). Several pretreatment meth-
ods (enzymatic prehydrolysis, microwave irradiation, sonification) were used to improve the course of
fermentation and were compared with separate hydrolysis and fermentation (SHF). Due to high water
binding capacity of raw material fermentations were conducted at a substrate loading of 150 g kgÀ1. Only
during enzymatic pretreatment and the SHF process the raw material was preliminary liquefied so its
higher concentrations could be applied. The dynamics of fermentation was similar in all studied variants.
The fermentation of unpretreated waste bread ended with 80.00% ethanol yield (354.36 g kgÀ1 of raw
material). Pretreatment of raw material improved ethanol yield by ca. 3–8%.