Sorption Water of Starch Granules

The amount of sorption water in various starch granules which equilibrate with different water vapour at 25°C, and 40°C were measured. Isosteric sorption heat was calculated by Clausius Clapeyron equation. 1) Hysteresis loop area in sorption and desorption of potato starch was the largest and diminished in order of tapioca, waxy rice, sweet potato and rice at 25°C. These values at 25°C were higher than at 40°C. 2) Unilayer sorption water in various starch granules was calculated by B. E. T. equation were approximately 7.7% (dry basis, 25°C). 3) Isosteric sorption heat was almost constant at more than about 20% sorption water.