A Study into Preparation of bio-ethanol by degradation of Banana stalks with enzyme

At present, ethanol production from lignocellulosic biomass is the most widely used. Banana is extensive planted in the south of China and its stalks contain 63.8 ± 0.5% (of dry materials) dissolved carbohydrates that can be degraded into pentose and/or hexoses, which can be suitable for bio-ethanol fermentation by yeast. The technics of the simultaneous sacchrification and fermentation was adopted with the novozyme (including NS50013 and NS50010), then the yeast was added into the mash after the hydrolysis time of 12 h. The factors influenced the bio-ethanol yield at the hydrolysis and fermentation were confirmed by single factor experiments. The results were shown on g/g of dry banana stalks. As the results shown, the hydrolysis conditions were enzymic dosage 0.6 ~ 1.0ml/100g fresh banana stalks, with the substrates/water ratio at 1:1, pH 4.8 ~ 5.5, hydrolysis 12 ~ 18 h at 35 ~ 40°C. The fermentation conditions were pH 3-5, inoculums yeast 0.8g/100g of fresh banana stalks, ferment 36 ~ 48 h at 40°C. Besides, the trace elements such as Mn, Zn, Fe, etc, also influence the bio-ethanol yields. When the trace elements' concentration were controled at the range of 0.5 ~ 0.8 ug/ml, the bio-ethanol yield increased nearly 10 ~ 20%. Under the optimal conditions, the bio-ethanol yields reached the climax at 0.40 g/g of dry banana stalks which equivalent to 80.5% of the theoretical yield.