Interaction effects of pH and inhibitors in oil palm frond (OPF) hemicelullosic hydrolysate on xylitol production: A statistical study

The degradation of sugars into less desirable compounds such as acetic acid and furfural are common during acid hydrolysis. The aim of this study was to evaluate the variables of pH, concentration of acetic acid and furfural on the production of xylitol utilising Kluyveromyces marxianus ATCC 36907 by employing full factorial design. The ANOVA results showed that at the 95% confidence level all three factors and interactions of initial pH of fermentation with acetic acid and furfural concentration were significantly affect the xylitol yield. The results of this experiment were fitted with the second order polynomial regression to relate the yield of xylitol and the independent variables. The fitted model showed a good agreement between the observed and predicted value of xylitol yield by Kluyveromyces marxianus ATCC 36907. The xylitol yield for bioconversion of detoxified dilute acid OPF hydrolysate was 0.29 g/g of xylose with the presence of 4 g/L of acetic acid and 0.5 g/L furfural. The fermentation process was carried out at initial pH 6.5. Results of these experiments indicated that the regression model equation was a valid method to evaluate the relationship of response and independent variables and to predict the xylitol yield based on the composition of major inhibitors present in the dilute acid oil palm fronds (OPF) hydrolysate. © Penerbit Universiti Sains Malaysia, 2017.