EVALUATION OF MALTS FROM SOME ACHA VARIETIES AS SOURCE OF ENZYMES FOR ETHANOL PRODUCTION FROM STARCHY MATERIALS
ABSTRACT
Three acha varieties were malted and their enzyme activities were compared with that of barley malt. The maximum amylase activity was achieved on day 3 for white and black acha but in the case of brown acha the maximum activity was obtained on day 4. Of the three varieties of acha and malted barley, white acha gave the highest amylase yield (50u/ml) and the least was exhibited by barley (26u/ml). Use of malted acha as source of enzyme for simultaneous hydrolysis and ethanol fermentation of two substrates (cassava and corn flour) under various conditions. (i) raw starch maintained at 500C for 30 minutes, (ii) raw starch at room temperature (270C), and (iii) gelatinized starch were investigated. The highest ethanol concentration was obtained with gelatinized starch. Comparison of acha malt with koji enzymes for simultaneous hydrolysis and ethanol fermentation under various conditions showed that acha malt gave significantly higher ethanol (P≤0.05) than koji enzymes under the three conditions. The effects of the ratio of acha malt to starch concentration on ethanol production was also studied. The highest ethanol concentration was obtained with acha malt and corn flour in the ratio of 2:1. The effect of yeast inoculum cell conceprntration on ethanol production was investigated and the highest concentration was obtained with inoculum cell concentration of 2×107 cells/50ml. Although high initial starch concentration gave the highest ethanol concentration, the highest ethanol yield was obtained with low initial starch concentrations. Effect of combining acha malt and koji on simultaneous hydrolysis and ethanol fermentation of starch showed that acha malt alone was better than the combination.