Using ethanol as pretreatment for improving drying of germinated quinoa grains

Abstract

The present work aimed to evaluate the effect of ethanol pretreatment on the drying kinetics of germinated quinoa grains and on its enzymatic activity. For that, quinoa grains were germinated for 12 and 24 h and then soaked for 30 and 60 s in ethanol (99% v/v) before drying. Afterward, they were dried in a convective air oven at 50 °C and 0.2 m/s of air velocity. In addition, desorption isotherms and enzymatic activity were evaluated. Further, the drying kinetics was fitted using Page and Fick models and desorption isotherms were fitted to GAB model. As main results, using ethanol as pretreatment increased the drying's initial velocity of ungerminated and germinated grains, reducing the drying time if the final moisture goal is between 10 and 15 %w.b. However, this improvement was not different comparing the immersion time in ethanol (30 s and 60 s). On the other hand, the isotherm behavior was not statistically different comparing ungerminated and germinated grains. Nevertheless, germinated grains by 12 h and pretreated with ethanol for 30 s increased the monolayer moisture up to 76%. Regarding enzymatic activity, germinated grains for 12 h showed the highest enzymatic activity. However, the use of ethanol caused its reduction.