Cation exchange capacity and buffering capacity of neutral‐detergent fibres

Dietary fibre buffers the gastrointestinal tract via the inherent buffering capacity of the specific fibre matrix, the quantity of cell wall ingested and the stimulatory effect of cell wall on rumination and/or salivation. The strong bonding of Cu 2+ ions for carboxy groups permits their use in estimating the cation exchange capacity (CEC) of both pectinaceous materials and pectin‐free cell wall fractions. The CEC values observed emphasise the different cation exchange capacities of the various plant cell wall components. Cellulose has a relatively low exchange capacity while lignin and Maillard products have a much greater adsorption. Emphasis is placed on the difficulty in utilising gravimetric determinations to interpret physicochemical effects as well as the diversity of plant sources in terms of gastrointestinal buffering.