S. L., JAGADEESHB. K., POOJAPASUPULETI, VIJAYANANDS. J., PRASHANTHEVOOR, SHASHIKANTHITIGI, PRABHAKAR2019-09-012019-09-012018-07UHS16PGM779http://krishikosh.egranth.ac.in/handle/1/5810125383An experiment entitled “Studies on dehydration of onion and tomato using 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 in case of onion and S1 - 0.5 cm slices, S2 -1 cm slices and S3 - Longitudinal quarters in case of tomato) and subjected to different chemical pretreatments 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. Onion slices dehydrated after pre-treatments (T2, T3 and T6) were subjected to storage in stand on PE-pouches for three months. During storage, T6 recorded significantly minimum moisture (initial-11.38% and 3 MAS-14.02%) and NEB value (initial-0.08 and 3 MAS-0.15), significantly higher pungency (initial-6.35and 3 MAS-4.83) and maximum sensory score for overall acceptability (initial-8.56 and 3 MAS-8.06). In dried tomatoes, the S3 (Longitudinal quarters) recorded significantly maximum recovery (5.01), titratable acidity (0.80%) and lycopene content (3.23 mg/100 g) followed by S2 (1cm). Most of the physico-chemical and sensory properties of dried tomatoes due to pre-treatments and control did not show significant differences. Therefore, tomatoes (S2 and S3) dehydrated without any pretreatment (T1-control) were packed in stand on PE-pouches and stored for three months under ambient conditions. Though S3 tomatoes absorbed more moisture and higher NEB values during storage, they were found better in retention of titratable acidity (Initial-0.77 and 3 MAS-0.48) and lycopene (Initial-3.04 and 3 MAS-2.65) representing characteristic taste and nutritional benefits associated with acidity and lycopene respectively. Therefore T6 of S2 in onion and T1 (Control) of S3 in tomato are concluded as best for dehydration under solar tunnel dryer.en-USnullThesis