Hot air convective drying of hog plum fruit (Spondias mombin): effects of physical and edible-oil-aided chemical pretreatments on drying and quality characteristics

This aim of this study was to evaluate the effects of pretreatments and temperature on the hot air drying characteristics of hog plum fruits. Hog plum fruits were pretreated with olive oil/K2CO3 or sunflower oil/K2CO3 at 28 degrees C and olive oil/NaOH cum blanching at 96 degrees C for 15s, hot water at 96 degrees C for 15s, and dried in a hot air drier at 50, 60, and 70 degrees C. Mathematical models were used to fit the data of drying and rehydration kinetics. Results showed that increase in temperature reduced drying time, increased effective diffusivity and shrinkage. Sunflower oil aided chemical pretreated sample had the shortest drying time (780 min) and highest effective diffusivity (6.3 x 10-8 m2/s) at 60 degrees C, faster rehydration ability at 60 degrees C, highest retention rate for ascorbic acid (15 %), phenolic content (29 %), and antioxidant activity (12.3 %), while olive oil aided chemical (K2CO3) pretreated sample had the shortest drying time at 50 degrees C (990 min) and 70 degrees C (600 min), lowest shrinkage (48.5 %), slower rehydration capacity at 40 degrees C, and lowest colour change (Delta E = 11.5). Modified Henderson and Pabis and Vega-G = alvez were superior to other fitting models in predicting the drying and rehydration kinetics. Sunflower oil/K2CO3 pretreatment could help improve the drying and quality characteristics of hog plum.