Drying kinetics of cabya (Piper retrofractum Vahl) fruit as affected by hot water blanching under indirect forced convection solar dryer

Abstract

East Java Province is one of main producers of cabya (Piper retrofractum Vahl) fruit in Indonesia. The fruit has huge utilizations and economic potential, but lack in postharvest process investigation. Traditional open sun drying by farmers has deficiency, e.g. unpredictable weather and longer process. In the present study, the indirect forced convection solar dryer was used to dehydrate the cabya fruit as affected by hot water blanching. The drying behavior, drying kinetics model and shrinkage of the fruit were evaluated. One kilogram of cabya fruit at the red edible maturity stage with 70.29 ± 2.89% (wb) of average moisture content was used as raw material for each with and without hot water blanching. Two units of forced convective solar dryers with identical specification consisting of solar air collector and drying cabinet were employed in parallel for 18 h in 3 days. The obtained drying data were fitted to 12 mathematical drying kinetics models. The moisture content of cabya fruit with and without hot water blanching was reduced to the final moisture content of 6% (wb) and 9% (wb), respectively. Among examined models, The Page model satisfactorily described cabya fruit drying kinetics. The results also indicated that hot water blanching affected significantly the drying behavior of cabya fruit. Significant shrinkage was also found in the final dried product of cabya fruit.