Efecto de la variedad y de la humedad de cosecha en la temperatura de transición vítrea de variedades uruguayas de arroz

Abstract

The glass transition temperature (Tg) of a material is the range of temperatures where the transition between a glassy and a rubbery state occurs, producing changes that are reflected in its physicochemical properties. The objective of this research is to determine the glass transition curves (Tg vs. grain moisture content) of three Uruguayan rice varieties and assess whether there are significant differences among them. The influence of the harvest moisture content (HMC) is also evaluated. To do this, each rice sample is dried for different periods of time to obtain grain moisture contents (GMC) in a range between 10% and 22% (on a wet basis). The Tg is then measured by differential scanning calorimetry (DSC). The results are compared by applying ANOVA and the Tukey test. It was observed that the Tg increases as GMC decreases for the three varieties studied. The glass transition curves show that there are significant differences among the three varieties in the range of GMC going from 12% to 16%. The HMC did not affect the Tg in the range studied. The results obtained can be applied to optimize the rice drying process, minimizing the formation of fissures.