Moisture Sorption Characteristics of Dehydrated Watermelon (Citrullus lanatusThunb)Pomace Wastes

Abstract

The moisture adsorption isotherms of watermelon pomace (“Namdhari” and “Sugar baby”) dehydrated in fluidized bed and cabinet dryer were obtained over a range of water activities and temperature varying from 0.113 to 0.920 at 20–50C, respectively. The adsorption power of dehydrated watermelon pomace waste decreased with increase in temperature at constant water activity. The moisture sorption isotherms of DWPW were sigmoid in nature. Chung and Pfost was the most efficient model among Type I models for both cultivars with coefficient of determination (R2) of 0.973–0.990, standard error (SE) of 0.082–0.096 and scattered residual plots. Among Type II models, Modified Henderson model gave best results with R2 of 0.967–0.982, SE of 0.167–0.234 and scattered residual plots. The variation of net isosteric heat of sorption for DWPW of both cultivars, estimated using the Clausius-Clapeyron equation, was 41.69–0.2 kJ/mol at 3–30% moisture content on dry basis. Practical Applications Watermelon pomace was discarded as waste, which can be used to obtain bioactive compounds. Dehydration is better alternative to increase the shelf life of pomace. The storage life of pomace was dependent on storage temperature and relative humidity (RH). Mathematical modeling was applied to study the moisture adsorption isotherm of watermelon pomace.