Characterisation of osmotically dehydrated papaya with further hot air drying and microwave vacuum drying


Correspondence: Fax: +66 2562 5005;



Papaya was subjected to osmotic dehydration (OD) prior to hot air drying (HA; 70 °C) and microwave vacuum drying (MVD; 3.75 W g−1 and 13.3 kPa). An increase in immersion time in a sucrose solution [65/100 g (w/w)] at 40 ± 2 °C from 0 to 4 h decreased moisture content from 7.5802 to 1.2215 kg water kg dry solid−1. During HA and MVD, effective moisture diffusivity was in the range 7.09 × 10−8 to 9.13 × 10−8 m2 s−1 and 2.85 × 10−6 to 3.50 × 10−6 m2 s−1, respectively, depending on immersion time. The hue angle of HA samples was 0.83–0.91, whereas that of MVD samples was 48.55–50.32. Both drying methods decreased springiness. Porosity was clearly observed in MVD samples. Rehydration rate was enhanced by increased immersion time and MVD (P ≤ 0.05). From preference mapping, MVD samples were more preferable than HA samples. Moreover, MVD samples with 1–3 h OD were more preferable than those with 4 h OD.