A comparative study of 3D CAD and fractal geometry models for analyzing mass transfer in shrimp during convective drying

Shrimp is a highly perishable and economically important seafood, making effective drying methods essential for preservation. Current shrimp drying models typically fall into two categories: high-fidelity 3D simulations with high computational cost, and analytical models using simplified shrimp geometry, both of which typically neglect product shrinkage. This study introduces a novel modeling approach which represents shrimp as a shrinkable, spherically symmetric object with a fractal dimension. The method was applied to analyze mass transfer (MT) during convective drying of pre-cooked shrimp at 70, 80, and 90 °C, both with and without dry salting pretreatment. The fractal dimension was determined by matching drying behavior to that predicted by a detailed 3D CAD model. A value of 2.38 was obtained, falling between that of an infinite cylinder (2) and a cylinder with equal height and diameter (2.63). For untreated shrimp, moisture-averaged effective diffusivities (accounting for shrinkage) were estimated using the 3D CAD model as 4.86, 5.40, and 7.04 (×10 -10 ) m 2 /s at 70, 80, and 90°C, respectively. Dry-salted shrimp showed slightly lower values: 4.78, 5.21, and 6.31 (×10 -10 ) m 2 /s under the same conditions; however, these differences were not statistically significant ( p > 0.05 ). The fractal object approach yielded diffusivity estimates that did not differ significantly from those obtained with the 3D CAD model ( p > 0.05 ). These findings indicate that the fractal object-based model can effectively approximate complex-shaped foods like shrimp for drying analysis and the estimation of MT properties. • Mass transfer (MT) during shrimp drying with/without dry-salting was analyzed. • 3D CAD modeling was used for MT analysis, accounting for product shrinkage. • A fractal object was also used to approximate shrimp shape during drying. • No significant differences in water diffusivities between approaches ( p > 0.05 ). • Fractal objects may approximate complex food shapes in MT studies.