4. Conclusions
Present study proved that waste wheat-rye bread is a high ethanol
yielding material in direct conversion to ethanol process using
GSHE resulting in ca. 354 g kg1 of raw material. Moreover application
of various raw material pretreatment methods (enzymatic
prehydrolysis, sonification and microwave irradiation) further
increased the ethanol yield by ca. 12–35 g kg1. However the studies
were conducted at low raw material loading due to water holding
capacity of bread what resulted in solid-like consistence of the
media at higher loadings. The solution to this seems to be the enzymatic
prehydrolysis which causes preliminary liquefaction of raw
material.