Hemicellulosic hydrolysates of agro-residues are promising raw materials for xylitol and arabinose production through biotechnological methods. Two-step acidic fractionation of corn fibre was developed to produce a glucose-and arabinose-rich hydrolysate and a xylose-rich hydrolysate. An integrated process of arabinose biopurification on the glucose-and arabinose-rich hydrolysate and xylitol fermentation on the xylose-rich hydrolysate using Candida boidinii NCAIM Y.01308 was introduced, in which cell mass produced in arabinose biopurification was used as inoculum in the xylitol fermentation. Aerobic biopurification resulted in an arabinose solution containing 9.2 g L-1 of arabinose with a purity of 90 %, based on total sugars. Xylitol fermentation under microaerobic conditions resulted in a xylitol yield of 53 % of theoretical and a xylitol concentration of 10.4 g L-1 in three days. Hence, an integrated biorefinery process of hemicellulosic hydrolysates was developed based on the diverse action of C. boidinii to purify arabinose and produce xylitol.

BACKGROUND The high cost of pure arabinose has resulted in a growing demand to develop new cost‐effective methods of arabinose production from lignocellulosic and pectin‐rich materials. Corn fibre is an inexpensive by‐product of the corn wet‐milling process, and is a promising raw material for producing arabinose and other value‐added products. In this study fast dilute sulphuric acid hydrolysis of corn fibre was investigated for selective arabinose solubilization. Acid concentration and reaction time of hydrolysis of destarched ground corn fibre and raw corn fibre were 0.25–5 w/w% at 5–15 min and 0.25–1.25 w/w% at 25–75 min, respectively. Results were evaluated statistically and model equations were developed to predict the yields of sugars. RESULTS In the case of raw corn fibre the most favourable conditions were 1.1 w/w% sulphuric acid concentration and 51 min reaction time at 90°C, where a total arabinose yield of 75.9% was achieved with satisfactory selectivity. In the case of destarched ground corn fibre at a sulphuric acid concentration of 4.6 w/w%, a reaction time of 5 min and a temperature of 90°C, a total arabinose yield of 80.5% could be achieved with satisfactory selectivity, according to the model equations. CONCLUSION Arabinose‐rich liquid fractions were produced by mild sulphuric acid treatments of corn fibre. Based on the models developed the mono‐ and oligosaccharide contents of the hydrolysates can be controlled under the conditions investigated. © 2014 Society of Chemical Industry