Standardization of size/shape and pre-treating chemicals for dehydration of onion under solar tunnel dryer
BK Pooja, SL Jagadeesh, SJ Prashanth, Shashikanth Evoor, Itigi Prabhakar
An experiment for standardization of size/shape and pre-treating chemicals for dehydration of onion under solar tunnel dryer was conducted in the Department of Post Harvest Technology, College of Horticulture, Bagalkot, Karnataka during the year 2017-18. Fresh onion and tomatoes were prepared for dehydration by cutting into different size/shapes (S1 - Dices and S2 - Slices of onion) and subjected to different chemical pre-treatments for a specified duration. Onions and tomatoes thus prepared were dehydrated in solar tunnel dryer and analyzed for different physico-chemical qualities. In dried onion, the slices (S2) recorded significantly minimum moisture content (13.80%), minimum drying time (57.17 hours), higher rehydration ratio (2.98) and significantly higher sensory score. Among pre-treatments, T2 (0.25% KMS for 15 min), T3 (0.1% KMS + 2% CaCl2 for 5 min) and T6 (0.5% Na2S2O5 for 20 min) were found superior with respect to various physico-chemical and sensory properties.