Effects of pH and Aeration Conditions on Xylitol Production by Candida and Hansenula Yeasts

Abstract

During the fermentative production of xylitol the following environmental parameters have a controlling effect on the xylitol yield: concentration of monosaccharides, temperature, aeration and pH. The purpose of the present work was to evaluate xylitol production by four yeast strains at different pH values and oxygen transfer rates (OTRs). The highest xylitol yields were obtained under the following conditions:
Candida parapsilosis: pH 5.0, OTR 6.1 mmol L-1 h-1;
Candida guilliermondii: pH 4.5, OTR 5.7 mmol L-1 h-1;
Candida boidinii: pH 6.0, OTR 5.7 mmol L-1 h-1;
Hansenula anomala: pH 4.5, OTR 2.8 mmol L-1 h-1 using 50 g L-1 initial xylose concentration.