Abstract:
-Usage of fossil fuel has been known to cause
adverse effects on the environment due to the emission of
harmful greenhouse gases. Production of bioethanol from
biodegradable waste material could be an alternative fuel
system to the expensive petroleum products. The objective
of the study was to determine the suitability of sour orange
peel as an effective substrate for bioethanol production
using baker’s yeast (Saccharomyces cerevisiae). The sour
orange peel extract was inoculated with Saccharomyces
cerevisiae with the fermentation media composed of
100 g/L sucrose, 5 g/L yeast extract, 10 g/L KH2PO4, 2
g/L (NH4)2SO4, and 0.5 g/L MgSO4·7H2O in order to
produce ethanol at room temperature for 24 hours. Ethanol
content produced from fermented sour orange peel was
measured by an Ebulliometer. Initially the amount of
ethanol produced from the orange peel extract was 5%
(v/v) at room temperature (30±2 °C) after 24 hours of
fermentation. When different inoculum size such as 0.5,
1.0, 1.5 and 2.0 g /100mL were used in the fermentation
media, ethanol production was increased to 5.25% when
inoculum size of 1.5 g /100mL was used. When different
carbon sources such as glucose, maltose, sucrose and lactose
were used in the fermentation media, ethanol production
was increased to 5.5% in media containing maltose. After
the optimization of culture conditions such as fermentation
time (24 hour) temperature (37oC) and pH (5.0), the
production of ethanol was significantly increased to 6.5%
in sour orange peel medium. When different nitrogen
source such as ammonium sulphate, ammonium nitrate,
ammonium chloride or urea was used in the fermentation
media, ethanol production was significantly increased to
7.5% in orange peel media containing ammonium nitrate.
The current study concludes that 7.5 % (v/v) ethanol (1.5
times higher) can be produced from sour orange peel
using baker’s yeast under optimized conditions including
maltose as the C source and ammonium nitrate as the N
source. Large scale fermentation study should be carried
out with bioreactor to determine whether this finding
could be commercialized.
