Hydration properties of dietary fibre and resistant starch: a European collaborative study

Hydration properties related to the fibre matrix have been defined and meas ured in 19 European laboratories using common methods and the substrates: r esistant 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 e xperimental variation or statistical tolerance, Measurement of swelling and WRC were complemented by measurement of water absorption and porosity. Swe lling (similar to 7 mL/g) and WRC (similar to 4 g/g) were relatively low fo r resistant starches and pea hull. Swelling and WRC of citrus (similar to 1 1 mL/g: similar to 11 g/g) and apple pulp (similar to 7 mL/g: similar to 5 g/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. (C) 2000 Academic Press.