• Energy Research

The subject of this study was to investigate the feasibility of the concentrate obtained after membrane ultrafiltration of sugar beet thin juice for ethanol production and selection of fermentation conditions (yeast strain and media supplementation). Resulting concentrate was subjected to batch ethanol fermentation using two strains of Saccharomyces cerevisiae (Ethanol Red and Safdistill C-70). The effect of different forms of media supplementation (mineral salts: (NH4)2SO4, K2HPO4, MgCl2; urea+Mg3(PO4)2 and yeast extract) on the fermentation course was also studied. It was stated that sugar beet juice concentrate is suitable for ethanol production yielding, depending on the yeast strain, ca. 85-87 g L(-1) ethanol with ca. 82% practical yield and more than 95% of sugars consumption after 72 h of fermentation. Nutrients enrichment further increased ethanol yield. The best results were obtained for media supplemented with urea+Mg3(PO4)2 yielding 91.16-92.06 g L(-1) ethanol with practical yield ranging 84.78-85.62% and full sugars consumption.

The use of field beans, a non-food leguminous crop, was studied for ethanol, feed components and fungal biomass production. The seeds were hydrolyzed using enzymes or with combination of acid (H3PO4) and alkaline (Ca(OH)2) pretreatment and enzymatic hydrolysis. Fermentation by Saccharomyces cerevisiae, with or without removal of suspended solids, yielded 38.3-42.5gL(-1) ethanol (71.3-79.2% efficiency). The filtration residues contained ca. 247-326gkg(-1) crude protein, 10.6-15.5% acid detergent fiber and 19.9-29.1% neutral detergent fiber. They were enriched in phenolics (by up to 93.4%) and depleted in condensed tannin (by up to 59.3%) in comparison to the raw material. The thin stillages were used for cultivation of edible fungus Neurospora intermedia which produced 8.5-15.9gL(-1) ethanol and 4.8-16.2gL(-1) biomass containing over 62% protein. The mass balances showed that fermentation of unfiltered mashes was more efficient yielding up to 195.9gkg(-1) ethanol and 84.4% of protein recovery.

Abstract 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).