Abstract

Apple pomace (AP) which accounts for 25% of original fruit mass is a by-product from the apple processing industry. Solid-state fermentation of AP was conducted on laboratory scale in 250 ml flask at 30°C, agitation speed of 55 rpm at different pH levels of 4, 4.5 and 5.0 using the Y₅₁ strain, Saccharomyces cerevisiae (SC) ATCC 9673 and their combination. The sample was treated with both α- amylase and cellulase enzyme collectively for higher reducing sugar content. Ethanol yield of 5.23% (v/v) was obtained in the case wherein strain Y₅₁ was inoculum at pH of 4.5 and the fermentation period was 72 h. Response surface methodology was used to design the experiments as well as for the data analysis. Optimization of various process conditions was done using software Design-Expert 7.1.6.

Key words: Apple pomace, saccharomyces cerevisiae, Y₅₁, cellulase, optimization.