Dados do Trabalho

Título

MATHEMATICAL MODELING AND EXPERIMENTAL EVALUATION OF HEAT AND MASS TRANSFER IN SHRIMP DURING CONVECTIVE DRYING

Introdução

Shrimp is one of the most consumed seafood in the world and has great economic importance for the fishing industry of many countries. It is a rich source of nutrients, containing about 20% of protein with essential amino acids and other micronutrients like calcium and selenium. Convective drying is a common technique used for its preservation. During the process, the shrimp temperatures rise while the moisture content reduces and the structure shrinks. Heat and mass transfer dynamics directly affect the dried shrimp's nutritional and quality attributes.

Material e Métodos

In order to describe this process, a mathematical model that considers heat and mass transfer in irregular-shaped material was proposed and validated using experimental data of shrimp drying in a convective oven. The transport phenomena considered in the model were thermal radiation, convective heat and mass transfer at the food surface, and heat conduction and moisture diffusion inside the shrimp. The thermophysical properties (density, specific heat, and thermal conductivity) were obtained by predictive models based on moisture content and local temperature; the convective heat transfer coefficient was estimated using the lump heat capacity method, and the moisture-effective diffusion coefficient was estimated from experimental data. Governing equations and initial and boundary conditions were solved numerically by the finite element method using the COMSOL Multiphysics® software.

Resultados e Discussão

The calculated values of the shrimp moisture and mid-layer temperature were compared with the experimental results (drying at 60 and 70 ºC), showing a good agreement between theoretical and experimental results (R² > 0.9 for all conditions). Besides, the model and experiments show that kinetic drying presents three phases: an initial phase with rapidly increasing temperature, followed by a phase with a constant drying rate and temperature, and a phase with a decreasing drying rate and increasing temperature.

Conclusão

The calculated moisture profile also showed that the tail section of the shrimp had lower moisture content than the thicker center portion, while the temperature distribution was more uniform. The mathematical model proposed in this study can be a useful tool for optimizing and designing the convective drying technologies applied to shrimp processing.