Extraction kinetics of saponins from quinoa seed (Chenopodium quinoa Willd)

Quinoa has higher protein content (11-16% m/m) and better amino acid profile than cereals and represents a valuable resource for healthy nutrition. The aim of this work was to study the saponins extraction kinetics during washing of soaked quinoa. The experimental curves of saponins content as a function of time was measured at water temperatures of 20, 40, 60, and 70ºC. A spectrophotometric method was proposed to determine total saponins content, while an unsteady state diffusional model was applied to this extraction problem, assuming strict internal control to the mass transfer rate. As a first analysis, the complete analytical solution for constant diffusion coefficient (Deff) using the initial radius (R0) provided an accurate predicted curve at each temperature. The diffusion coefficients (around 10−10 m2s-1), were correlated with temperature using an Arrhenius-type relationship to obtain an activation energy Ea  of 16.9 kJ mol-1.  The preliminary values of Ea and preexponential factor (D0) thus obtained were used as initial values of a second, more robust fitting where the whole dataset of saponins concentrations as a function of time for all temperatures. The Arrhenius equation was directly inserted into the diffusional solution. The following parameters were obtained: Ea= 17.2 kJ mol-1 and, D0= 3.232×107 m2 s-1, respectively with an overall r2=0.985. Saponins content agreed well with experimental values. As the equation is capable of predicting saponin extraction times for various operating conditions, it can be used within equipment design schemes

Caracterización física y obtención de parámetros de fluidización de germen de trigo

El germen de trigo es el embrión del grano de trigo, presenta un elevado contenido de tocoferoles y proteínas y ácidos grasos y proteínas de alta calidad. A su vez, contiene enzimas con elevada actividad que limitan su periodo de aptitud a unos pocos días. El objetivo del presente trabajo fue caracterizar físicamente las partículas de germen de trigo para determinar los parámetros de diseño para un proceso de fluidificación térmica con aire. Los ejes principales de las partículas fueron determinados mediante análisis de imágenes y sus dimensiones y parámetros geométricos fueron calculados. La densidad de lecho fijo y la porosidad del lecho fueron determinadas. Los estudios fluido-dinámicos nos permitieron determinar los coeficientes, laminar (277,46±17,48) y turbulento (7,79±0,69) de la ecuación de Ergun y la velocidad de mínima fluidificación (0,35±0,02 m/s).Wheat germ is the embryo of de wheat seed, it contains a high tocopherol and protein content, and high quality proteins and fatty acids. Also, wheat germ has a considerable enzymatic activity that limits its shelf life. The aims of the study were to physically characterize wheat germ particles to determine their design parameters of thermal fluidization process with air. The principal axes of the particle were measured by image analysis, and their dimensions and geometric parameters were calculated. The fixed bed density and the void fraction were measured. The fluid-dynamic studies allowed us to determine laminar (277.46±17.48) and turbulent (7.79±0.69) coefficients of the Ergun equation and the minimum fluidization velocity (0.35±0.02 m/s).Centro de Investigación y Desarrollo en Criotecnología de Alimento