Neutral-sugar determination by HPAEC-PAD to characterise polysaccharide degradation by colonic bacteria

 In vitro methods are widely used to characterise dietary fibre fermentability in the human hind gut. The activity of faecal bacteria can be followed by measuring fermentation products and substrate degradation. This paper describes a method for establishing neutral-sugar profiles by HPAEC-PAD during in vitro fermentation studies. Freeze-dried fermentation residues are hydrolysed with H₂SO₄, and the monomers are separated on an anion-exchange column using a reverse NaOH gradient. Sulphate ions are removed from hydrolysates on-line with a special ion-exchange guard column. 2-D-deoxyribose is used as internal standard for quantification. A method for separating all neutral sugars that typically occur in dietary fibre is given. Possibilities for enhancing the resolution for other purposes are suggested. Compared to GC the described method is particularly attractive for routine analyses. Data relating to the decreasing levels of neutral sugars in fermentation residues of oat bran fractions that differ in their mixed-linked β-glucan content are given and degradation patterns of the polysaccharides present in these substrates are discussed. Received: 26 February 1997