Effects of dietary fibre-rich juice colloids from apple pomace extraction juices on intestinal fermentation products and microbiota in rats

Effects of colloids isolated from apple pomace extraction juices (so-called B-juices) produced by enzymic liquefaction on food intake, body and faecal weights, short-chain fatty acid (SCFA) profile and selected intestinal microbiota were investigated in rats. Ten male Wistar rats per group were fed diets without any apple dietary fibre (DF) (control) or supplement with 5% B-juice colloids or an alcohol-insoluble substance (AIS) from apples for 6 weeks. Rats fed with apple DF (5% B-juice colloids or AIS) gained less weight than control rats (P<0.05). B-juice colloids did not affect food intake, whereas feeding AIS resulted in a 10% higher food consumption than in control rats. Both juice colloids and AIS increased the weight of caecal contents in rats and lowered luminal pH values (P<0.05). In addition, SCFA concentrations and total yields were also raised (P<0.05) in caecum of these rats indicating good fermentability of apple substrates by gut microflora. Distinctly higher concentrations of acetate and propionate were found in intestinal contents of juice colloid-fed rats (P<0.05), whereas AIS also increased butyrate yield. Changes in microbiota due to apple DF in diets were restricted in the caecum to the Eubacterium rectale cluster (AIS; P<0.05) and in faeces to the Bacteroidaceae (juice colloids and AIS; P<0.05). The present study shows the physiological effects of apple DF isolated from pomace extraction juices produced by enzymic liquefaction on intestinal fermentation. Results may be helpful for the development of such innovative juice products that are rich in DF of fruit origin.