Abstract

This article aims at determining thin-layer drying curves for grains of lima bean, variety olho-de-peixe and to predict them using diffusion models. Samples of lima bean (110.0 g) with initial moisture content of 66.0% (wet basis, wb) were dried at temperatures of 40.0, 50.0 and 60.0°C. The effective diffusivity of moisture was determined by analytical solutions of the mass diffusion equation (Fick’s second law) with prescribed boundary condition for spherical, cylindrical, and infinite slab at each temperature. Comparison with the experimental data showed that the infinite slab with constant diffusivity predicted more accurately, but statistical indicators of the goodness of fit were not completely satisfactory. Thus, a model for the infinite slab with constant volume, moisture-dependent diffusivity and convective boundary condition was numerically integrated. This model was solved by the numerical method of finite volumes with fully implicit formulation. The values obtained for the diffusivity were between 5.58 x 10^-9 and 6.39 x 10^-8 m² min^-1, being the activation energy 28.4 kJ mol^-1. The model satisfactorily describes the drying process of this lima bean cultivar under all conditions investigated.

Submitted: May 13, 2008 · Accepted: July 20, 2009 · Published: July 31, 2009

Recommended Citation

da Silva, Wilton Pereira; Precker, Jürgen W.; and de Lima, Antonio Gilson Barbosa (2009) "Drying Kinetics of Lima Bean (Phaseolus lunatus L.) Experimental Determination and Prediction by Diffusion Models," International Journal of Food Engineering: Vol. 5 : Iss. 3, Article 9.
DOI: 10.2202/1556-3758.1440
Available at: http://www.bepress.com/ijfe/vol5/iss3/art9