Effect of lactic acid fermentation of wheat and barley whole meal flour oncarbohydrate composition and digestibility in mink (Mustela vison)

Wheat and barley whole meal flours (WMFs) were subjected to treatment by fe rmentation, autoclaving, and fermentation followed by autoclaving. The WMFs were analysed for chemical composition, formulated into wet diets (282 g k g(-1)) and fed to adult mink (Mustela vison) for determination of total tra ct digestibility of total starch, total carbohydrate, crude protein and fat . Fermentation of WMF/water mixtures inoculated with a Lactobacillus sp. (s train AD(2)) was performed at 30 degreesC for 16 h. Autoclaving was carried out for 60 min at 120 degreesC. Fermentation increased colony-forming unit s (CFUs) to about 10(8) g(-1) and lowered pH to 3.7-3.8 in both WMFs. All c arbohydrate parameters were affected by type of cereal, and were, except fo r total starch, affected by treatment. Levels of total dietary fibre and be ta -glucans decreased by Fermentation in both WMFs. The decrease in total b eta -glucans from 33.5 to 18.4 g kg(-1) in barley WMF, was mainly restricte d to the soluble fraction. Glucose levels in barley WMF increased simultane ously from 0.6 to 12.3 g kg-l. The main effects of autoclaving were increas ed levels of total dietary fibre, maltose, and increased hydration capacity . With fermentation prior to autoclaving, increases in levels of the fibre fractions and maltose were prevented while hydration capacity prevailed as an effect of autoclaving. Compared with fermentation alone, the combined tr eatment increased damaged starch levels and hydration capacity. Digestibili ties of total carbohydrate, crude protein and fat were significantly higher for wheat than for barley. Fermentation had no effect on digestibility of total starch or total carbohydrate of wheat, but increased digestibility of total starch of barley significantly from 0.742 to 0.880, and of total car bohydrate from 0.457 to 0.616. Autoclaving had no significant effect on dig estibility of total starch and total carbohydrate of wheat. Digestibility o f total starch and total carbohydrate in barley increased significantly aft er autoclaving. Total starch and total carbohydrate digestibility of both w heat and barley were significantly enhanced by combined fermentation and au toclaving compared with fermentation alone. Compared with autoclaving alone , combined fermentation and autoclaving promoted no significant improvement of total starch and total carbohydrate digestibility in wheat, whereas tot al carbohydrate digestibility in barley increased from 0.605 to 0.672. Fat digestibility was slightly improved by both fermentation and autoclaving. A utoclaving of cereals reduced significantly the faecal dry matter contents of mink. This effect could be counteracted by preceding fermentation. in co nclusion, lactic acid fermentation of wheat and especially barley provided chemical changes of benefit for carbohydrate digestion in the mink. (C) 200 1 Elsevier Science B.V. All rights reserved.