Ethanol production from <i>Washingtonia robusta</i> fruits by using commercial yeast

Abstract

In this study, ethanol production from fruits of Washingtonia robusta was investigated. Effects of different contact times (1 - 24 h), pH (2 - 12) temperature (20, 30, 40, 50°C) and autoclave pretreatment (121°C, 10 min, 1.2 atm) were also studied to improve the solubility of reducing sugar in fruits. Baker’s yeast (Saccharomyces cerevisiae) was used for fermentation of that reducing sugar. Results showed that solubility of reducing sugar increased with increasing contact time. Optimal pH and temperature for solubility of reducing sugar were 6.8 - 7.2 (deionized water) and 50°C. HPLC analysis showed that samples contained only glucose and fructose as a sugar source. Autoclave pretreatment protected the samples from contamination and increased the reducing sugar concentration up to 105 g/L. Ethanol production reached up to 25 g /L at the end of eight days by using commercial yeast. Bioethanol yield was found to be 71.42 ± 1.4 g ethanol/kg fruit.

Keywords: Ethanol, fruit, reducing sugar, Washingtonia robusta