Drying Kinetics of Chives (Allium fistulosum L.)

Abstract

Chives are herbs used as spice in Brazil, but their postharvest durability is short, mainly due to high metabolic rate and high moisture content. In this context, this study aimed to model the drying curves of chives at different temperatures and determine the effective diffusion coefficient and activation energy for the process. Chives were manually harvested, with moisture content of 12.0 (decimal, dry basis) and subjected to drying until reaching equilibrium moisture content, i.e., minimum amount of free water. The fitting capacity of eleven mathematical models used to evaluate drying processes in agricultural products was assessed. Treatments consisted of two physical patterns of length, whole and chopped leaves(pieces of approximately 2 cm and whole leaves of approximately 20 cm long, respectively), and four drying air temperatures (40; 50; 60 and 70°C). The fit of the studied models was assessed by nonlinear regression through the Gauss-Newton method. Among the mathematical models tested, Midilli was the one that fitted best to the experimental data. Increasing drying temperature leads to higher rate of water removal from the product.