초록
<P><B>Abstract</B></P> <P>Conversion of pomegranate peel (PP), which is an abundant and valuable by-product of fruit juice industry to value added product such as ethanol, instead of discharging as agro-industrial waste was aimed in this study. Some important parameters such as H<SUB>2</SUB>SO<SUB>4</SUB> pretreatment (0.5%, 1%, 1.5% v/v), fermentation period (6, 12, 24 h), initial substrate loading (from 2.5 to 150 g/L) were optimized in the first fermentation experiments performed with <I>S. cerevisiae</I> and <I>P. stipitis</I> yeasts. After finding the optimum conditions for ethanol production of the yeasts, effect of different nitrogen sources [yeast extract – peptone and (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>] and metal salts (combination of K<SUP>+</SUP>, Mg<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Zn<SUP>2+</SUP>) on the production were also investigated to improve the yield, up to 44.9% for <I>S. cerevisiae</I>, which reached to 5.58 g/L at the end of 12 h fermentation, corresponding to 0.46 g/L/h productivity, whereas <I>P. stipitis</I> could produce 2.95 g/L ethanol. This study shows that pomegranate peel is a promising feedstock for second generation ethanol production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The first study on bioethanol production from pomagranate peel. </LI> <LI> <I>Saccharomyces cerevisiae</I> and <I>Pichia stipitis</I> were used for ethanol production. </LI> <LI> Important parameters and the content of the fermentation media were optimized. </LI> <LI> We succeeded to increase the ethanol yield produced by <I>S. cerevisiae</I> up to 44.9%. </LI> <LI> Q<SUB>p</SUB> and Y<SUB> <I>P/S</I> </SUB> of <I>S. cerevisiae</I> increased to 0.46 g/L/h and to 0.43 g/g, respectively. </LI> </UL> </P>