Abstract:
This study was carried out to produce bioethanol from low quality over
ripen Musa sapientum (sour banana) fruit wastes to enhance the yield of
bioethanol. When the sour banana juice was inoculated with Saccharomyces
cerevisiae (2 g/L) in the fermentation media (100 mL, 8o Brix) composed
of 10 g/L yeast extract, 10 g/L KH2
PO4
, 2 g/L (NH4
)2
SO4
, 2 g/L peptone,
and 0.5 g/L MgSO4
·7H2
O and fermented for 24h at 30 °C and 100 rpm,
the ethanol yield was 0.8% v/v. When nitrogen sources urea, ammonium
sulphate, ammonium carbonate, and ammonium nitrate were used in the
fermentation media (2.0 g/100mL), significantly higher ethanol yield
(p<0.05, 0.90%) was produced with ammonium carbonate. When yeast
inoculum was increased to 5 g/L, the ethanol yield was significantly higher
(p<0.05, 1.00%, 1.11 times) than the control. When the temperature was
25 °C, the ethanol yield was significantly increased (p<0.05) by 1.2 times
the control temperature of 30 °C. When the rotation speed was 150 rpm,
the ethanol yield was significantly higher (p<0.05) than the control (100
rpm). Ethanol yield was significantly higher (p<0.05, .15 times - 4.10 %) with 90% of banana juice. With 0.1 g/100mL of ammonium carbonate,
ethanol yield was significantly increased by 1.1 times (p<0.05, 40 %) than
the non-optimized control (0.2 g/100mL). Sucrose significantly stimulated
ethanol yield than the other sugars. Fifteen grams per hundred milliliters
of sucrose yielded significantly higher ethanol (p<0.05, 2.33 times) than
the non-optimized control (2 g/100mL). When the pH of the medium
was optimized at 6.0, the ethanol yield was significantly higher (p<0.05,
12.60%). Therefore, Musa sapientum could be an effective substrate for
bioethanol production and optimization process increased the bioethanol
yield significantly by 15.75 times (12.60% - 1.6o
Brix).
