Abstract:
The production of bioethanol from diverse peel wastes of underutilized
fruits could be one of the alternative fuel systems. The objective of the study was to
determine the effect of culture conditions and media composition to increase the bio-
ethanol yield from pineapple peel using baker’s yeast. The fruit peel juice of pineapple
(Ananas comosus) was inoculated with Saccharomyces cerevisiae (baker’s yeast- 2
gL-1) in the fermentation media (total volume100 mL), pineapple fruit peel wastes
(10g/100mL) composed of 10 gL-1 yeast extract, 10 gL-1 KH2PO4, 2 g L-1 (NH4)2SO4,
2 g L-1 Peptone and 0.5 g L-1 of MgSO4•7H2O and allowed for fermentation for 12
hours at room temperature. The ethanol produced from the pineapple fruit peel waste
mixture was 0.30% (V/V) at room temperature after 12 hours of fermentation. The
conditions were optimized sequentially by changing one factor at a time while keep-
ing the other variables constant. Significantly higher bioethanol yield [5.0 times, 1.5%
V/V (P<0.05)] was obtained from pineapple peel waste at the following optimal con-
ditions of 12 hours of incubation period, 5:1 ratio between air space and fermentation
solution, 1.5 g L-1 of yeast inoculum, 10 g 100 mL-1 of pineapple fruit peel, 0.5 g 100
mL-1 soybean powder and 60 mL 100 ml-1 of diluted sulfuric acid. When the pH of
the medium was changed from 3.0 – 8.0, a significantly higher ethanol yield (2.8%)
was obtained when the pH of the media was kept at 5.0. Thus, bioethanol yield was
significantly increased by 9.34 times, (2.8%) when fermentation conditions of pine-
apple peel waste by yeast were optimized. Therefore, pineapple peel waste could be
recommended as a good source for bioethanol production using yeast.
