Continuous Ethanol Fermentation from Cocoa Pulp Liquid Waste Using Immobilized Yeast Cells

Abstract

The cocoa bean pulp juice i s a waste of cocoa estate which has not been well utilized so far. Amounted at about 10 % of the bean wet weiqht, this waste could be used as a substrat for ethanol fercentation since its suqar content is relatively hiqh i.e. 10 - 15 %. The obiectzve of this experiment was to-study the continuous prohuction of ethanol from the waste using immobilized Saccharomyces cerev isiae. Immobilization was carried out usinq entrapment system in calcium a1inate beads. Fermentatzon was run continuously in a pacgedbed reactor at various dilution rates and an initial sugar content of 15 %. The results showed that a dilution rate of 0.028 hour-', which was equivalent to a residence time of 36 hours, gave the highest ethanol concentration i.e. 6.9 % (w/v) and a sugar-toethanol converszon efficiency of 95 ,%. This result was higher than that of a batch fermentatzon.