It was observed that application of all pretreatment methods
used in present study increased the final ethanol yield in comparison
to unpretreated waste bread fermentation (Table 2). For enzymatically
and microwave pretreated waste bread fermentation
with GSHE and SHF process the yield of the process was the highest,
in the case of other variants lower ethanol yields were
achieved, but still they were very high (above 80% of theoretical).
The highest values of ethanol productivity were achieved in all
studied samples within the first day of fermentations. Between
the second and third day of fermentation the changes in the yields
and productivity for all studied variants of experiment did not
change significantly what suggested that these processes could
be shortened to 48 h.