Hydration Properties of Dietary Fibre and Resistant Starch: a European Collaborative Study

Hydration properties related to the fibre matrix have been defined and measured in 19 European laboratories using common methods and the substrates: resistant starches, pea hull, citrus pulp and apple pulp. Swelling and water retention capacity (WRC) were the major hydration properties studied. The objective was to derive standardized methods with an included estimate of experimental variation or statistical tolerance. Measurement of swelling and WRC were complemented by measurement of water absorption and porosity. Swelling (∼7 mL/g) and WRC (∼4 g/g) were relatively low for resistant starches and pea hull. Swelling and WRC of citrus (∼11 mL/g: ∼11 g/g) and apple pulp (∼7 mL/g: ∼5g/g) were lower than expected, probably reflecting effects of processing on matrix structure. Coefficient of variation was higher between laboratories than within laboratory. The relationship between swelling, WRC, absorption and porosity, as well as matrix effects, are discussed.