Extraction and in vitro fermentation of rye bran fractions

Rye bran was fractionated on a pilot scale into water-extractable, alkali-extractable and unextractable fractions. The fractions were enzymatically digested to partially remove starch and protein. The enzyme treated Substrates were fermented in vitro using a human faecal inoculum. The water- and alkali-extractable fractions were fermented faster than the unextractable fraction and rye bran itself. However, the extent of fermentation after 24 h was similar in each case. The production of gases and short-chain fatty acids correlated well with the consumption of neutral sugars. All the rye substrates enhanced the molar proportion of propionic and butyric acids, among the short chain Fatty acids. (C) 2001 Academic Press.