Birch pulp xylan works as a food hydrocolloid in acid milk gels and is fermented slowly in vitro

The objective was to evaluate the potential of birch xylan as a food hydrocolloid and dietary fibre. High-molecular weight xylan was isolated from birch kraft pulp by alkaline extraction, and enzymaticallyhydrolysed. Fermentability of xylans was evaluated using an in vitro colon model and performance as ahydrocolloid was studied in low-fat acid milk gels (1.5% and 3% w/w). Texture of the gels and water holdingcapacity of xylans were compared with inulin, fructooligosaccharide and xylooligosaccharide. Xylansshowed slower fermentation rate by faecal microbiota than the references. Xylan-enriched acid milk gels(3% w/w) had improved water holding capacity (over 2-fold) and showed lower spontaneous syneresis,firmness and elasticity when compared to control (no hydrocolloids) or to references. In conclusion,birch xylan improved texture of low-fat acid milk gel applications, and the slow in vitro fermentationrate predicts lower incidence of intestinal discomfort in comparison to the commercial references.