EFFECTS OF DRYING TEMPERATURES ON DRYING KINETICS, PHYSICAL, FUNCTIONAL, NUTRITIONAL, AND ANTI NUTRITIONAL PROPERTIES OF AMARANTH SEEDS AND CHEMOMETRIC ANALYSIS

Abstract

The aim of this work was to study the drying kinetics of amaranth seeds at three different temperatures and its effects on physical, functional, nutritional and anti-nutritional properties. The amaranth seeds were collected from Kathmandu organics, a grocery store in Kathmandu, Nepal. Three different drying temperatures 40, 50 and 60 °C were selected for the drying of amaranth seeds in a cabinet dryer. When comparing the fresh with the samples of dried amaranth, it was observed that the drying operation led to reductions of 8.5% in proteins, 2.0% in ashes, 4% increase in crude fiber, and fat content was changed by approximately 3%. Amaranth seeds dried at 60 °C showed maximum retention of the phytochemical constituents and maximum reduction of anti-nutritional factors. In this study, moisture data of 40, 50, and 60°C were fitted to six drying models to provide an appropriate kinetic model and drying temperature for the drying process. The average value of coefficient of determination R2, χ2 and RMSE revealed values varied between 0.9724-0.9973, 0.0362-0.1567 and 0.0176-0.0533, respectively. The Midilli et al. model obtained the highest R2 and least χ2 and RMSE at all temperatures and better reflected the drying mechanism of amaranth seed and was determined to be the best fit for determining the proper drying temperature and drying kinetics for amaranth seeds. The effective diffusivity calculated using Fick’s diffusion equation varied from 1.1592 × 10-8 m2/s at 40 °C to 1.9716 × 10-8 m2/s at 60 °C. The activation energy and D0 for cabinet drying of amaranth seed at temperature from 40 to 60 °C were found to be 22.99 kJ/mol and 7.86 × 10-5 m2/s, respectively.