Processing of hazelnut (Corylus avellana L.) shell autohydrolysis liquor for production of low molecular weight xylooligosaccharides by Aureobasidium pullulans NRRL Y–2311–1 xylanase

Abstract

In this study, a versatile process for the production of xylooligosaccharides (XOS) with a low degree of polymerization (DP 2–6) from hazelnut shells was designed. This process included autohydrolysis integrated with sequential enzymatic hydrolysis by crude xylanase produced with Aureobasidium pullulans NRRL Y–2311–1 from wheat bran. Autohydrolysis of hazelnut shells was carried out at a solid:liquid ratio of 1:6 (w/w) and 190 °C non-isothermally. The effects of several parameters on enzymatic hydrolysis of the autohydrolysis liquor were determined. The maximum XOS (DP 2–6) production was 22.5 g/L which was obtained at pH 5.0 and 40 °C using enzyme concentration of 240 U/g XOS and substrate concentration of 72 g/L. Under these conditions, 31.29 % of the substrate (total XOS) was converted to low-DP-XOS; xylobiose and xylotriose are being the major oligomers. This is the first study on the application of A. pullulans xylanase in production of xylooligomers from hazelnut shells.