DRYING KINETICS OF SLICED TURMERIC (CURCUMA LONGA L.) IN A SOLAR-BIOMASS INTEGRATED DRYING SYSTEM

Drying of food product helps in reducing the water activity of the farm product to a level below which deterioration does not occur for a definite duration. Spices are invariably dried and used in powdered form. Turmeric is one of the main spices of India which is 80 % of the world's supply of commercial turmeric in fresh weight per year. A natural convection solar-biomass integrated drying system (IDS) was designed and developed. The system was capable of generating adequate and continuous flow of hot air of temperature between 55 and 60C from ambient temperature of 28-30C during experimentation. Blanched turmeric rhizomes were successfully dried. The moisture content was brought down to 6.68 % (db) from initial level of 831.09 % (db). Among different thin layer drying models tested, Page and Modified Page models were found as best fit, when simulation was done for all the drying data. The effective moisture diffusivity of turmeric was calculated as 1.667 X 10(-9) m(2)s(-1). Effective drying time in IDS was 14 h while in traditional open sun drying (OSD), the same was 25 h. Negligible effect of drying on curcumin content was observed during the study.