Kinetics of starch digestion in potato (Solanum tuberosum) flours: Innovative modelling and relationships with particle size

Abstract

Particle size-starch digestibility relationships were investigated in cryo- and hammer-milled (11 sizes) non-fractionated (compositionally homogeneous) potato flours. Hydration, pasting, structural, gelatinisation, colour, and time-course in vitro starch digestion properties were studied, revealing particle size differences as the sole factor. The flours’ starch digestograms were adequately (p ≤ 0.05) modelled with recent objective logarithm of slope procedure, and multiterm exponential and non-exponential equations. Heterogeneity tests significantly (p ≤ 0.05) revealed true mono-, bi-, and tri-phasic digestograms in the flours. Digestion parameters showed an inverse relationship with the particle size, the square (Ap 2 ) of which linearly (p ≤ 0.05) related with the reciprocal of the rates of starch digestion (1/K) of the multiphasic starch digestograms. The inverse slope of 1/K-Ap 2 plots (0.04–2.58 × 10 −7 cm 2 s −1 ) revealed a diffusion-controlled digestion process. The study presents an innovative modelling of starch digestograms and the first particle size-starch digestibility relationships in multiphasic digestograms. Starch digestibility in potato: Innovative modelling and particle size effects. • Potatoes were dried, and cryo- and hammer-milled to 11 particle sizes. • Pasting and gelatinisation temperatures were independent of the particle size. • Innovative modelling revealed true mono-, bi-, and tri-phasic starch digestograms. • Starch digestion parameters inversely related to the particle size of the flours. • The particle size-rate of digestion relations showed enzyme diffusion mechanisms.