Temperature effect on drying kinetics of ‘Gigante de Valinhos’ figs

Author: H. C. Pacco ¹, C. Vigneault ^{1, 2*}, L. R. de Castro ³, F. C. Menegalli ³ and L. A. B. Cortez ¹

Received 4 January 2007, accepted 28 March 2007.

Abstract

The drying kinetics of bleached skinless figs was studied under different operating conditions. The samples were subjected to three air temperatures (45, 60 and 75ºC) at a constant air velocity of 1 m s^-1. The process efficiency was analyzed on the basis of moisture content and in relation to water activity, apparent density, shrinkage coefficient and color. As expected, the final moisture contents varied from 1.9 to 0.03% as the temperature of the air that was used increased and as the relative humidity decreased. The apparent density increased from 1.025 to 1.186 g mL^-1 during the drying process and was linearly related to the volume, as the volume decreased the apparent density increased. The final volume of the produce was 7.8 times smaller than the initial volume. A linear shrinking coefficient of 0.8779 was obtained, revealing that the dimensionless volume decreased faster than the dimensionless moisture content. Minor color changes were observed when figs were dehydrated at 60ºC, the temperature that provided the best drying conditions with respect to maintenance of produce quality.

Key words: Ficus carica L., shrinkage, color, drying, fig, kinetic.