Effect of pretreatments and endo-1,4-β-xylanase hydrolysis of canola meal and mustard bran for production of oligosaccharides.

Abstract

Alkali/acid-pretreated canola meal and mustard bran were subjected to endo-1,4-β-xylanase (T. longibrachiatum) hydrolysis for oligosaccharide production. Pretreatments significantly (α = 0.05) increased the relative content of pentose sugars, especially in alkali-pretreated canola meal (∼44 %) and mustard bran (∼72 %). The amounts of pentosan (g/100 g) in acid- and alkali-pretreated canola meal were 7.50 and 8.21 and in corresponding mustard bran were 8.67 and 10.39, respectively. These pretreated substrates produced a pentose content (g/100 g) of 2.10 ± 0.14 (18 h) and 2.95 ± 0.10 (24 h), respectively, during hydrolysis. As per UPLC-MS data, the main oligosaccharides in the hydrolyzates of alkali-pretreated substrates are xylo-glucuronic acid and xylobiose. The release of total phenolics of the hydrolyzates increased until 18 h irrespective of the type of substrate or pretreatment. Hydrolyzates of acid-pretreated substrates indicated more total antioxidant activity than alkali-pretreated substrates, attributed to its high phenolic content. The study suggests the potential of canola meal and mustard bran for the production of oligosaccharides, wherein the use of various combinations of cell-wall-degrading enzymes and its optimization may result in a better yield, with simultaneous production of endogenous phenolics.