Table of Contents
Journal of Food Processing
Volume 2014, Article ID 175402, 9 pages
http://dx.doi.org/10.1155/2014/175402
Research Article

Moisture Diffusivity and Shrinkage of Fruit and Cladode of Opuntia ficus-indica during Infrared Drying

1Thermal Process Laboratory, Energy Technologies Research Center (CRTEn), Borj Cedria, BP 95 Hammam-Lif, Tunis 2050, Tunisia
2Higher Institute of Environmental Sciences and Technologies, Carthage University, Tunisia
3Chemical Engineering Department, Faculty of Engineering, King Khaled University, P.O. Box 394, Abha, Saudi Arabia

Received 15 November 2013; Revised 10 February 2014; Accepted 24 February 2014; Published 3 April 2014

Academic Editor: Franco P. Pedreschi

Copyright © 2014 Amira Touil et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Drying behaviour of prickly pear cladodes and fruits was studied with an Infrared dryer. The volume shrinkage for Opuntia ficus-indica products is calculated and a linear relation was established to describe the experimental variation of shrinkage of the product versus its moisture content. Effective diffusion coefficient of moisture transfer was determined using the Fick law at three drying temperatures (40, 50, and 60°C). Shrinkage was also included into the diffusion model for the determination of the effective diffusion coefficient. The obtained results of the effective moisture diffusivity, for the cladode and the fruit, were evaluated in the range of 1.77 × 10−10–5.07 × 10−10 m2/s and 2.53 × 10−10–7.6 × 10−10 m2/s, respectively. The values of the activation energies for cladode and fruit were estimated to be 45.39 and 47.79 kJ/mol, respectively. However, these values of moisture diffusivity were estimated independently of the evolution of moisture content during drying process. Therefore, a correlation (full quadratic equation) for moisture diffusivity as a function of moisture content and temperature was developed. The parameters are obtained by a multilinear regression method. This equation was found satisfactory to describe the diffusivity evolution function of moisture content and temperature with correlation coefficients of 91.5 and 95%.