Characteristics and mathematical modeling of convective drying of quinoa (chenopodium quinoa willd.): influence of temperature on the kinetic parameters
2010
VEGA-GÁLVEZ, ANTONIO | San Martín, Ricardo | SANDERS, MARIELA | Miranda, Margarita | LARA, ELENA
The aim of this research was to model the drying kinetics of quinoa and to evaluate the temperature influence on the kinetic parameters of the models used. Prior to drying process, quinoa grains were washed at 60C and the removal of saponins was studied. Hot air drying temperatures were 40, 50, 60, 70 and 80C. Initial saponin content was 6.34%, reaching a final saponin content of 0.25% after 120 min of washing. Sorption isotherm was determined at 60C giving a monolayer moisture content of 0.051 g water/g dry matter. Drying kinetics was modeled with different equations. Diffusional coefficient increased with temperature from 3.78 to 7.67 × 10⁻¹¹ m²/s, for a range of temperatures between 40 and 80C, with an estimated of Ea 15.95 kJ/mol. According to the statistical tests used, the logarithmic and Weibull models gave the best fit for experimental data (determination coefficient > 0.98, sum squared error < 0.001 and Chi-square < 0.001). PRACTICAL APPLICATIONS: Quinoa (Chenopodium quinoa Willd.) is mainly cultivated in Argentina, Bolivia, Chile, Colombia, Ecuador and Peru. Today, it has aroused great technological and commercial interest for both human and animal feeding because of the presence of high-protein content and a balanced amino-acid spectrum with significant lysine and methionine contents. In addition, it does not contain gluten, being an alternative food for celiac patients. In the last few years, it has shown to have an antioxidant activity like other cereals and pseudocereals (buckwheat, rice, soybean, amaranth, among others), playing an important role as functional and nutraceutical food. The main utility of this study is the application of dehydration as an alternative for the preservation of this pseudocereal, applying different empirical models and the diffusional model, which can be considered a base for the estimation of the drying time and the optimization of the drying process.
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