Hot-air drying characteristics of tomato slices at optimum drying temperature

Tomato slices (Pusa Rubi) were dried at 45, 55, 65, 75, 85 and 95°C. Browning index-indicative of color was measured after extracting the coloring matter from dried slices. Minimum browning index of 0.209 was recorded at 65°C drying temperature and is, thus, the safest temperature for drying tomato. The rehydration ratio obtained at this temperature was 4.57. Moisture content during hot-air drying at 65°C decreased exponentially with time reaching storage moisture in 5 hours. Equilibrium moisture content estimated at 65°C was 3.02% d.b. Study of drying rate curve at 65°C indicated that almost entire drying took place in falling rate period with a slight inflection during the later stage of drying.