Influence of Arsenic Concentration on Mass Transfer in Cooked Carrots

Abstract

This thesis aims to study the diffusion of arsenic in carrots. The specific objective was to measure how arsenic diffuses using Fick's law, with concentrations ranging from 5 to 15 mgL-1 at a constant temperature. Whole carrots, with their skin, were cooked at 98°C in solutions with different levels of arsenic (5, 10, and 15 mgL-1). The carrots were cut into three parts: upper, middle, and lower. To calculate the arsenic diffusion coefficients, a homogeneous cylindrical model was used. Conditions were established to solve the mathematical model and to select the boundaries and diffusion mechanism. The results showed consistency with the increasing arsenic concentrations (5, 10, and 15 mgL-1) in the solution at 98°C during 30 minutes of cooking. The average diffusion coefficients in the upper region were 1.45E-08, 1.49E-08, and 1.53E-08 m²s-1 for arsenic concentrations of 5, 10, and 15 mgL-1, respectively. Additionally, it was observed that the arsenic concentration was related to the radial distance and penetration into the carrot tissue, as well as the height of the cut. At 5 mgL-1, diffusion was lower than at 10 and 15 mgL-1 for the same times, as the rate of arsenic advancement decreased with lower concentration. In all three regions (upper, middle, and lower), the arsenic content decreased from the periphery towards the center of the carrot, similar to other studies on solute diffusion in foods. Part of the results and methodology were published in the journal HELIYON.