Cabya (Piper retrofractum Vahl) fruit under open sun drying: Drying behavior and modeling of thin layer drying kinetics

Cabya (Piper retrofractum Vahl) fruit is one of Piper species, which indigenously grown in East Java Province, Indonesia, has huge utilizations but lacks postharvest processing investigation. The present study aimed to quantify moisture removal characteristic as well as to determine thin layer drying kinetics model, which represent the drying behavior of cabya fruit under open sun drying. The effect of blanching pre-treatment on the drying behavior of cabya fruit was also evaluated. The cabya fruit at the red edible maturity stage with 68.57±2.20% (wb) of average moisture content were used as raw material. The moisture content, drying rate, and moisture ratio during drying (18 and 24 h in three and four days) were measured and calculated. The calculated moisture ratio data were fitted to the twelve commonly used thin drying kinetics models. The results indicated that blanching pre-treatment affected greatly on drying behavior, i.e., final moisture content, drying rate, and drying kinetics. From all twelve drying kinetics models investigated, Midilli et al. model is found as the best one to depict cabya fruit drying kinetics in both blanching treated and untreated, based on its coefficient of correlation (R), root mean square error (RMSE) and reduced chi-square (χ ²).