Pumpkin peel dehydration using a fluidized bed contactor: a technical and environmental study

Abstract

Pumpkin peel (PP) contains protein, fiber, and other nutrients, transforming it into an important food source. Considering these beneficial characteristics, the work aims to valorize it through dehydration in a fluidized bed contactor. Dehydration of PP cubes was carried out at 60 and 70 ºC, and the beneficial characteristics of the PP were studied. The dehydration effect (for both temperatures) on the nutritional characteristics was negligible. The minimum air velocity in the fluidized bed contactor was experimentally determined, finding a value of 1.64 m s-1. Dincer and Dost´s model was used to determine the mass transfer characteristics. Water transfer is governed by internal and external resistance. The obtained values of effective diffusivity and mass transfer were in the ranges from 15.01×10−9 to 17.83×10−9m2 s-1 and from 2.51×10−6 to 4.30×10−6 m s-1, respectively. The technical and environmental evaluation of dehydration was carried out by exergetic analysis. The exergy efficiency and dehydration time decrease with the temperature, conversely, the environmental impact increases. Despite observing slight nutritional variations, this study recommended drying at 70 °C because the water activity is favorable and its dehydration time is shorter due to the increase of diffusion and mass transfer coefficients.