Water Absorption Kinetics of Guar Seeds and Unhulled Guar Splits

Abstract

Water absorption characteristics of guar seeds and unhulled splits were investigated at 20 to 60 °C. Results indicated that galactomannan was the major constituent responsible for higher absorption of water by guar. Rate of water absorption and the saturation moisture content of unhulled splits were higher than that of seeds due to increased galactomannan content in splits. Fick’s law and three empirical models (exponential, Peleg’s and Weibull distribution function) were evaluated to describe the water absorption behaviour of guar seeds and splits. The water absorption took place in two falling rates period. Shift of first to second falling rate period was found to be irrespective of temperature and started from 0.96 and 2.01 kg kg−1 dry matter for guar seeds and unhulled splits, respectively. The Weibull distribution function adequately described the water absorption kinetics of guar seeds and unhulled guar splits in both falling rate periods. The activation energy values for water absorption for guar seeds and unhulled splits were 13.69 and 27.94 kJ mol−1 in first falling rate period and 11.70 and 27.66 kJ mol−1 in second falling rate period, respectively.