Characterization of fermentation of waste wheat-rye bread mashes with the addition of complex enzymatic preparations

There were prepared mashes from wheat-rye bread residues at concentration of 32% (w/w). In a control sample amylolytic enzymes were used (α-amylase and glucoamylase). Studied samples were prepared using complex enzymatic preparations Cremix 2XL and Ceremix 6X MG containing proteases and enzymes degrading non-starch polysaccharides. Mashes were inoculated with Saccharomyces cerevisiae Ethanol Red yeast and subjected to the fermentation. The addition of complex preparations led to shortening the fermentation time to 72 h in comparison to control sample (93 h). Initial glucose concentration was similar in all samples, while the addition of Ceremix preparations increased the concentration of maltose and maltotriose in obtained mashes. In fermentation media prepared with supportive enzymes carbohydrates were consumed by yeast at a higher rate. Highest glycerol concentration was formed in fermentation feed prepared with Ceremix 6X MG (8.01 gL−1). Acetic acid concentration was similar in all samples during the fermentation (ca. 0.5 gL−1), while most of succinic acid was formed in the control media (2.11 gL−1 after 69 h of process). The most advantageous physiological condition of yeast biomass after fermentation process featured the media prepared with Ceremix 6X MG (75.35% of budding cells, 5,88% inactive cells). The addition of Ceremix 2XL and Ceremix 6X MG preparations resulted in significant increase in ethanol yield in wheat-rye bread mashes (35.53 and 36,60 g ethanol per 100 g of bread dry matter respectively) in comparison to control sample (35.24 g ethanol per 100 g of bread dry matter).

► Waste wheat-rye bread as fermentation feed.
► Mashing with addition of complex enzymatic preparations.
► Addition of complex preparations shorten the fermentation time.
► Addition of complex preparations increases ethanol yield.