Ethanol Production from Acid Pretreated Food Waste Hydrolysate Using Saccharomyces cerevisiae 74D694 and Optimizing the Process Using Response Surface Methodology

Ethanol production from acid pretreated food waste hydrolysate using immobilized Saccharomyces cerevisiae 74D694 was investigated under different conditions in a batch experiment. Ethanol yield was measured at different time intervals (38, 48, 72, 96 and 105 h) using different immobilized bead ratios (25:100, 30:100, 40:100, 50:100 and 54:100, w/v). Food waste was pretreated using dilute sulphuric acid and the hydrolysate was filtered. The dry food waste had an initial reducing sugar content of 46% (w/w). After dilute acid pretreatment, reducing sugar content increased to 62%. The present study utilized liquid hydrolysate for ethanol production. The process was optimized using central composite design (CCD) a statistical tool used for optimization in response surface methodology (RSM). RSM predicted a maximum ethanol yield of 0.044 g/g of soluble solid in liquid hydrolysate at 40 h fermentation time and immobilized bead ratio of 54:100 (w/v). An experiment was run at the optimal condition and an ethanol yield of 0.047 g/g of soluble solid in liquid hydrolysate was obtained. The predicted result was thus experimentally verified