Performance Evaluation of Solar and Oven Drying for Tropical Fruits

Abstract

Solar drying is the common traditional method to preserve fruits by reducing its moisture content and the microorganisms’ activities, hence, slowing down the mold growth, which affect the quality of fruits. Operational cost of solar dryer can be cheaper but the drying time using solar dryer is usually longer than other drying techniques that use electricity due to the lower and inconsistent temperature within its drying chamber. In this work, bananas, papaya and pineapple were dried using an oven at temperatures of 65-85oC, and the results were compared with the outcomes of drying using a simple wood solar cabinet dryer, done in Kota Samarahan, Sarawak Malaysia. The drying profiles for the fruits dried in the oven were found to be quite similar, indicating the insignificant variation in the cell matrix structure of the fruits, and in addition, these results were supported by the small range of the estimated drying constants between 1.32 - 1.83 10-1 hr-1. Moreover, the results showed that the increase in the temperature of drying in the oven from 65 to 75oC did not change the drying time significantly, but the drying time was reduced significantly to 70% when the temperature was increased to 85oC. The fluctuation of temperature and air flow within the solar dryer between 27-34oC and 0.12 -1.52 m/s, respectively, slowed down the drying process, resulting to prolong of drying time. The drying time to reduce the moisture content from 80-60% for the solar drying was between 31 to 74 hours while for oven drying with temperatures of 65-85oC was between 1-5 hours.