Drying of Ginger, Turmeric and Guduchi in solar-biomass hybrid drier

429 Zingiber officinale Rosc. (Ginger), Curcuma longa Linn. (Turmeric) and Tinospora cordifolia (Willd.) Miers. ex Hook. f. & Thoms. (Guduchi) are the important spices and herbs. Ginger and turmeric are widely grown in different regions of India and are commercially important edible spices. Guduchi, as a drug plant, has bulk demand in the market ranging from 300 to 500 tonnes of dry woody stems annually. All these three products required careful drying before producing them to the market. Various drying techniques are employed to dry different food products. Each technique has its own advantages and limitations. Choosing the right drying techniques is thus important in the process of drying of these perishable products. The Brace type solar drier is one of the few designs that have achieved some level of acceptance. One significant disadvantage of this drier is that it is normally not used with any form of back-up heating. To reduce its dependence on solar radiation for operation and to improve the quality of drying, a biomass stove was incorporated with solar drier. It has extended the period of drying beyond sunshine hours, and perhaps during night as well, while drying high-value products. The scientists at Center for Rural Development and Technology, Indian Institute of Technology, New Delhi, evaluated the performance of the solar-biomass hybrid drier against ‘solar-only’ and open sun conditions. Experiments have been conducted to test the performance of the drier by drying of ginger, turmeric and guduchi during the summer climate in Delhi. It was found that, during the load test for ginger, 18 kg of fresh product with an initial moisture content of 319.74(db)% was dried to a final moisture content of 11.8(db)% within 33 hours. Similarly, moisture content of turmeric and guduchi Spices