OPTIMIZATION OF DRYING AND STORAGE PARAMETERS OF SOLANUM XANTHOCARPUM USING MOISTURE ISOTHERMS
This study was conducted to establish the optimum temperature and RH conditions for drying an important medicinal herb Solanum xanthocarpum and to propose appropriate storage conditions using moisture sorption isotherms and safe moisture content for long term storage. The best-fit mathematical model was determined for the moisture sorption data of the mature harvested crop to be able to predict moisture status of the herb for various applications in future research and development and quality control. Test samples were collected at the recommended maturity stage when the first leaves started to dry and berries turned yellow. Moisture sorption isotherms were developed by the gravimetric static method at two pre-determined temperatures. 30 and 50°C were selected based on the storage temperature and the conventional drying temperature, and at the water activity range of 0.05-0.83. Equilibrium Moisture Content (EMC) was measured by the Dean and Stark method. The experimental results were compared with five selected sorption mathematical models: the Modified Henderson, Modified Chung-Pfost, Modified Halsey, Modified Oswin and GAB equations. The best-fit model was evaluated using statistical parameters: coefficient of determination (R2), mean relative error, standard error of estimate and randomness of residuals. The GAB model was found to be the best-fit model for both adsorption and desorption data under both temperatures. Furthermore, 5% dry basis moisture content was found as the monolayer moisture content, which could be recommended as the final moisture content after drying for long-term storage without quality deterioration. The best relative humidity (RH) for packaging and long-term storage of the dried crop without moisture adsorption at the average room temperature of 30°C was 20%.
Dharmasena, D.A.N., Herath, H.M.W.P., Sivananthawerl, T. and Palipane, K.B. (2014). OPTIMIZATION OF DRYING AND STORAGE PARAMETERS OF SOLANUM XANTHOCARPUM USING MOISTURE ISOTHERMS. Acta Hortic. 1054, 229-236
ayurvedic medicine, equilibrium moisture content, GAB model, monolayer moisture content, relative humidity, sorption isotherms, water activity