KINETICS OF MASS TRANSFER DURING CONVECTIVE DEHYDRATION OF COATED OSMOSED PINEAPPLE SAMPLES

Abstract

ABSTRACTThe pineapple samples were coated with sodium alginate (0.5–5%) and osmosed in sucrose solution. The effect of coating and temperature (55, 65 and 75C) on the convective dehydration characteristics and quality parameters of dried pineapple samples were studied. The mass transfer kinetics were then evaluated. The dehydration time for the uncoated sample was less than the coated sample at all the three temperatures. The drying rate of the uncoated sample was more than the coated sample. The effective moisture diffusivity varied in the range of 2.09 × 10−10–3.42 × 10−10 m2/s. A nonlinear regression procedure was used to fit five thin‐layer drying models to the experimental drying curves. The models were compared using the coefficient of determination, mean relative percent error, root mean square error and reduced chi‐square. The Midilli model has shown a better fit to the experimental drying data as compared with other models.PRACTICAL APPLICATIONSThe treatment of coating before osmotic dehydration helps in reducing the problem of large solute intake without affecting much on the water removal. The fruits obtained by combining coating, osmotic dehydration and convective dehydration exhibit better nutritional quality, good appearance and extended shelf life. The product can be used in the areas of nonavailability of fruit. The fruits after rehydration can be added in ice cream, yoghurt and confectionary products.