Purification of biotechnological xylitol from Candida tropicalis fermentation using activated carbon in fixed-bed adsorption columns with continuous feed

Abstract

Xylitol, a sugar substitute, presents considerable amount of benefits for both product applications and consumer health, which make it a high value product for various industries. The production of xylitol through yeast fermentation is an alternative that suits sustainable development, as it can use agro-industrial byproducts, and might come to reach a lower production price than the current method in use once its technology is further developed. While there is extensive research in the process up to the synthesis of xylitol, the purification process to attain the final product is still not well consolidated. In the present work, tests were performed to assess the capacity of purification of xylitol containing fermented media by activated carbon in fixed bed columns. Response surface methodology with pulse input was utilized to investigate how the process responses vary when temperature, superficial velocity and injection volume are altered, and to define which conditions maximize productivity and minimizes xylitol retention while maintaining satisfactory levels of clarification. The best condition found (T = 70 °C, vs = 1.5 cm/min, Vi = 3 mL) was then applied to a new purification test with continuous feeding of fermented media. The process presented as a potential alternative for biotechnological xylitol purification step with efficacy in separating proteins (PFprotein = 18.0), colored compounds (reducing more than 99% of absorbance at 420 nm and 560 nm) and ethanol (PFethanol = 20.4) with a productivity of 36.8 g L−1 h−1 and RCxylitol = 31.1%.