Intestinal degradation of dietary fibre in green beans: Effects of microwave treatments

Intestinal degradation of dietary fibre in blanched and microwaved green beans was studied by using a rat experimental model. Content and composition of dietary fibre as well as molecular weight distribution of water-soluble polysaccharides (WSP) were analysed. There was a solubilization and a shift towards lower Mw of mainly uronic acid-containing polysaccharides with repeated microwave treatment in the raw material. Thus, the apparent Mw of water-soluble polysaccharides decreased from ~1 550 000 to ~300 000. After the beans had been digested the Mw of the WSP was significantly reduced, to ~100 000, and the differences in Mw seen between various processed raw materials had been evened out. After fermentation the Mw of the WSP decreased further ~10 times. Fibre fermentability was high (~90%) and similar for the various processed beans.