Moisture diffusivity in quinoa (Chenopodium quinoa Willd.) seeds: Effect of air temperature and initial moisture content of seeds

The moisture diffusivity in quinoa (Chenopodium quinoa Willd.) seeds were evaluated as a function of the air drying temperature and the initial moisture content of seeds obtaining values between 2.53 × 10−12 m2/s (30 °C, 12.87% d.b.) and 7.67 × 10−11 m2/s (90 °C, 23.44% d.b.). From a statistical analysis based on a factorial experiment, moisture diffusivity showed higher dependence with drying air temperature than with the initial moisture content at P < 0.01.A model based on an Arrhenius-type equation, temperature-dependence was proposed to estimate the activation energy in quinoa seeds. An average value of 37.97 kJ/mol (standard deviation 3.9 kJ/mol) was obtained for the range of temperature evaluated.Linear correlations between moisture diffusivity and the inverse of the absolute temperature was obtained for all the initial moisture contents evaluated, with regression coefficients above 0.94 (significant at P < 0.05).ANOVA test reported a significant interaction at P < 0.05 for both temperature and initial moisture content on moisture diffusivity. Based on these results, a linear relationship initial moisture content-dependence was proposed for the pre-exponential Arrhenius factor. A good agreement was found for the equation proposed (D = (B · M0 + C) · exp(−Ea/RT)) obtaining a correlation coefficient of 0.97 (significant at P < 0.05).