Diffusive Model with Shrinkage in the Thin-Layer Drying of Fish Muscles

Abstract

Fish fillets present large variation in volume during drying, due to their high initial moisture content. A kinetical study on the drying of fish muscles in slabs shaped with constant air conditions at three temperature levels is presented. For the modeling of the drying process of these materials, a diffusive model can be used, assuming a one-dimensional volume change. A linear correlation was considered between the thickness of the material and its moisture content, where the linear shrinkage coefficient has been determined. The resulting dimensionless nonlinear partial differential equation was solved numerically by the finite differences technique.

Diffusive model with variable effective diffusivity considering shrinkage in thin layer drying of chitosan

“…(8) into Eq. (4), in the dimensionless form, according to Pinto and Tobinaga (2006), Eq. (9), used for the falling rate period of the drying, was obtained.…”

“…Viollaz and Suarez (1991) used this procedure in the potato drying, while Pinto and Tobinaga (1994) used this model for the study of fish muscle drying.…”

“…The authors used this model in the study of the gel slabs drying, with 2.0 mm and 1.2 cm of thickness, respectively, determining the local profile of moisture content in function of the thickness, which was variable with time. Viollaz and Suarez (1991) and Pinto and Tobinaga (1994) presented a diffusive model including shrinkage in the dimensionless form, considering the volumetric effective diffusivity constant and equilibrium at the material surface (Eq. (1)).…”

“…Volume variation of food during drying is analyzed through the coefficient of linear shrinkage (a), that is related to the material thickness, similar to the equation of thermal expansion determination, as described in Pinto and Tobinaga (2006). The authors determined the linear shrinkage coefficient for fish muscle, which was practically constant during the constant rate period and the first phase of the falling rate of drying.…”

Condições de secagem de uma pasta de anchoita modificada enzimaticamente na oxidação lipídica, lisina disponível e atividade antioxidante do produto

“…A remoção de umidade durante a secagem é muito afetada pela temperatura do ar e pelas características dimensionais do material, o que pode ocasionar alterações de qualidade no produto, como o aumento nos produtos de oxidação lipídica (OLIVEIRA et al, 2010). O efeito dos parâmetros de secagem na remoção de umidade, expressos por modelos cinéticos, tem sido estudado para diferentes espécies de pescado (PINTO & TOBINAGA, 2006;VEJA-GÁLVEZ et al, 2011). A anchoita é uma excelente fonte proteica e rica em ácidos graxos poliinsaturados (CZERNER et al, 2011), assim, pode-se aproveitar o potencial de pesca da anchoita, utilizando a modificação enzimática de suas proteínas, associada à operação secagem para produzir um produto com melhores propriedades funcionais e nutricionais.…”