Determination of Bioethanol Production from Apricot (Prunus armeniaca) Pomace

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.

Improvement of bioethanol production from pomegranate peels via acidic pretreatment and enzymatic hydrolysis.

The aim of this study was to improve the ethanol production from pomegranate peels (PPs). Therefore, the effect of enzymatic hydrolysis and different pretreatments on ethanol production by yeasts was examined. There were three different enzyme concentrations (3.6, 7.2, 14.4 FPU/g substrate) tested for enzymatic hydrolysis, and four different PP media, such as WSPP (whole slurry of PP), LFPP (liquid fraction of PP), WSFPP (washed solid fraction of PP) and N-WSFPP (non-washed solid fraction of PP), were prepared. Bioethanol production was monitored for 96 h. Maximum ethanol concentrations were obtained at WSPP medium as 12.69 g/L, 14.35 g/L and 4.23 g/L in Saccharomyces cerevisiae, Kluyveromyces marxianus and Pichia stipitis, respectively. On the other hand, the washing step of biomass increased the kinetic parameters dramatically and the highest theoretical ethanol yields and YP/S values were obtained from WSFPP medium in all tested yeasts. Theoretical ethanol yields were 97.8%, 98.7% and 35.5% for S. cerevisiae, K. marxianus and P. stipitis, respectively. Qp values were observed as 0.98 g/L h, 0.99 g/L h and 0.04 g/L h for the same yeasts. The highest YP/S values were detected as 0.50 g/g for S. cerevisiae, 0.50 g/g for K. marxianus and 0.30 g/g for P. stipitis in the washed pomegranate peel biomass.

Efficient approaches to convert Coniochaeta hoffmannii lipids into biodiesel by in-situ transesterification.

Coniochaeta hoffmannii was isolated from soils contaminated with biscuit factory wastes showed the maximum lipid accumulation capacity in the study. Lipid production was optimized in terms of pH, carrot pomace loading, nitrogen type and amount, incubation time. Solvent, alcohol type and catalyst concentration, dried/wet biomass concentration, reaction approaches and time were optimized for lipid extraction and transesterification. The highest lipid accumulation was found as 52.0% at pH 4 in the presence of 10% carrot pomace, 0.5 g/L cheese whey at the end of the 48 h incubation. The maximum total C16 and C18 FAME rates were detected at the 25 °C, in the presence of 4 g/L dried C. hoffmannii biomass, methanol and 3% NaOH by using the in-situ transesterification process at the end of the 0.5 h as 96.3%. This is the first report about the usage of C. hoffmannii lipids obtained from carrot pomace for sustainable biodiesel production.