SUGAR COMPOSITION OF DIETARY FIBER AND SHORT-CHAIN FATTY-ACID PRODUCTION DURING IN-VITRO FERMENTATION BY HUMAN BACTERIA

The aim of the present study was to assess the relationship between th e disappearance of dietary fibre sugars and the production of individu al short-chain fatty acids (SCFA). The bacterial degradation of five d ietary fibres whose sugars were quantified was investigated in vitro u sing a human faecal inoculum. Involvement of the main fibre sugars in SCFA production was evaluated by a stepwise multiple linear regression . The results show first that the nature and chiefly the associations between the fibre sugars were key variables in the fermentability. Sec ond, the nature and the amounts of SCFA produced were closely related to the in vitro fermentation of the main sugars available: uronic acid s seemed to be principally involved in the production of acetic acid w hereas the production of propionic acid could be promoted by the ferme ntation of glucose and, to a lesser extent, by that of xylose and arab inose. Xylose tended to have a greater impact than uronic acids and gl ucose on the production of butyric acid. Thus, it would be possible to predict which SCFA could be specifically produced during the fermenta tion of a fibre, as far as the chemical composition and structure of t his fibre are known.