Residual Carbohydrates from in Vitro Digested Processed Rapeseed (Brassica napus) Meal

Abstract

Rapeseed meal (RSM) was subjected to different physical or chemical pretreatments to decrease residual, hard to degrade carbohydrates and to improve fermentability of RSM polysaccharides. Next, these pretreated samples were in vitro digested and fermented, with or without the addition of commercial pectinolytic enzymes. Remaining carbohydrates were quantified, and two physical characteristics were analyzed: (1) water-binding capacity (WBC) of the insoluble residue and (2) viscosity of the soluble fraction. Mild acid pretreatment in combination with commercial pectinolytic enzyme mixtures showed best digestion of RSM carbohydrates; only 32% of the total carbohydrate content remained. For most pretreatments, addition of commercial pectinolytic enzymes had the strongest effect on lowering the WBC of the in vitro incubated RSM. In the cases that less carbohydrate remained after in vitro digestion, the WBC of the residue decreased, and less gas seems to be produced during fermentation.