Convection drying of food and vegetables is a slow and energy-intensive process and takes a long time, up to 25 h, to complete the drying process depending on the drying conditions due to the high latent heat of vaporization of water, the low or limited rate of internal transport of water to the product surface, particularly in food, and the inefficiency of using hot air as drying medium. Accordingly, it is imperative to find the optimum drying conditions for economical operation. In this work, the effect of temperature (40, 50, 60, and 70°C) and the thickness of the slices (2, 4 and 6 mm) on the cassava drying process were evaluated. the samples of Manihot Esculenta Crantz, variety Ica Catumare (CM-523) were placed in perforated trays 12.5 cm * 13.1 cm with an air velocity of 2.34 m/s, leaving 70% free for drying air recirculation; drying time (t s ) and effective diffusivity ( D eff ) and activation energy (E a ) of cassava slices were determined, conforming to mathematical models to describe drying kinetics. The results showed a significant effect of drying temperature and slice thickness, decreasing drying time as air temperature increases and slice thickness decreases, achieving a 93% reduction of the initial moisture in the cassava slices. The mathematical model that best described the kinetics behavior of the drying curves was Page with a linear regression (0.995 ≤ R2 ≤ 0.998) and RMSE of 0.001–0.005. The effective diffusivity coefficient varied according to its thickness (2, 4, and 6 mm) between 3.164E -8 and 5.526E -8 m 2 /s, 1.568E -8 and 2.872E -8 m 2 /s, and 1.067E -8 and 1.967E -8 m 2 /s, respectively. The activation energy (E a ) varied between 19.092, 19.464, and 19.519 Kj/mol, which is within the ranges of agricultural products. Color changes of cassava slices were not negative considering the values of L*, a* and b*; achieving low values for a* and b* and high luminosity, usual characteristics of dry products. It was possible to determine the effect and influence of temperature on the reduction of cassava moisture content, observing an increase in the rate of free moisture loss with increasing temperature. The predominant period in drying was the decreasing period since most of the time is spent in this period. Keywords: cassava, drying curves, mathematical modeling, color, diffusivity, activation energy. https://doi.org/10.55463/issn.1674-2974.50.6.6
Tópico:
Food Drying and Modeling
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FuenteJournal of Hunan University Natural Sciences