Studies on Solar Drying of Kokum (Garcinia Indica) Rind and Its Quality Evaluation

Abstract

Kokum rind was dried from 85.32 % (w.b.) moisture content to 11.17% (w.b.) moisture content in a solar tunnel dryer in 34 h. Ten mathematical drying models were fitted with the experimental data on moisture ratio and time required for drying. Wang and Sing drying model fitted best with r2 value of 0.998 and RMSE of 0.000536. Variation in solar intensity inside and outside of the dryer was 180.51±58.51 W.m-2 and 434.68±120.34 W.m-2, respectively, with the ambient air temperature ranging between 40.9 oC and 55.36 oC, product temperature ranging between 28.76 oC and 55.67 oC, and humidity ranging between 20.00 and 39.99 per cent. Drying efficiency of the solar tunnel dryer was 22.94 per cent. Kokum rind quality parameters as acidity, reducing sugar, non-reducing sugar, protein, carbohydrates, ash, calorific value significantly increased after drying at p≤0.01, while pH, anthocyanin, colour (L, a and b value) significantly decreased at p≤0.01.