Abstract Fruit juice industry generates massive amount of lignocellulosic by-products annually which are excellent raw materials for bioethanol production. In the current study, bioethanol production from apricot (Prunus armeniaca) pomace by Kluyveromyces marxianus was investigated for the first time. Some key parameters for fermentation such as pretreatment methods, biomass and cellulase loading and time, were optimized. Kluyveromyces marxianus produced 30.09 g/L ethanol in the 20% washed apricot pomace and 120 FPU/g cellulose enzyme loading. The highest theoretical yield and Y P/S values were also observed as 94.7% and 0.50 g/g, respectively, when 15 FPU/g cellulose enzyme was used. These results depict that apricot pomace is a promising feedstock for bioethanol production.

The lignocellulosic substances such as agricultural wastes are promising feedstocks for bioethanol production. Because they are cost effective, renewable, abundant and not having primary value for food and feed. The current study suggests that improvements in polysaccharide hydrolysis of under-utilized biomass of carrot pomace may find practical use in its conversión to bioethanol by Saccharomyces cerevisiae and Pichia stipitis fermentation. Some important parameters for bioethanol production such as pretreatment procedures (CaO and activated charcoal treatments), nitrogen sources ((NH)2SO4, soy wheat, cheese whey), and pomace loading amount (15-120 g/L) were optimized in the study. The highest bioethanol production could be achived when the saccharification and fermentation conditions were optimized in order to increase monosaccharide yield and fermentation of both six-carbon and five-carbon monosaccharides. The bioethanol production was 1.9 -fold higher for S. cerevisiae and 4.6 -fold higher for P. stipitis when (NH4)2SO4 was added in addition to the trace nitrogen substances, vitamins and minerals present in carrot pomace. The highest bioethanol production values were obtained as 6.91 and 2.66 g/L in the presence of 120 g/L pomace loading, 1 g/L (NH)2SO4 at the end of 72 hours incubation time at pH 6 by S. cerevisiae and P. stipitis, respectively.