A tentative rough model for water binding in potato starch based on vapour sorption isotherms and calorimetric data is proposed. Heats of immersion and derived thermodynamic quantities are given. A constant differential net heat of sorption for the first 10% of water on dry starch was found. Sorption isotherms for water vapour of native and gelatinized potato starch showed good agreement with the Guggenheim sorption equation up to water activity 0-93 and with the Brunauer Emmet and Teller sorption equation up to water activity 0.3. The water binding mechanism was absorption, without evidence of capillary condensation, up to water activity of 0.95.

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