Preserving Bioactive Compounds in Wheat Germ Through Drying: a Kinetic Study

Abstract

In this study, wheat germ was dried at three different temperatures (80 degrees C, 90 degrees C, and 100 degrees C) using an oven. The drying characteristics of the samples were analyzed, and the experimental data were fitted to five different thin-layer drying models: Logarithmic, Lewis, Henderson and Pabis, Page, and Modified Page. Among these models, the Page and Modified Page models provided the best fit, yielding the highest R2 values and the lowest RMSE and chi 2 values. The overall drying process occurred in the falling rate period in all experiments. Bioactive compound degradation was also assessed during drying process. Lutein content decreased by 37.24-49.22%, total phenolic content decreased by 41.41-43.67%, and total antioxidant activity decreased by 31.25-45.70%. The degradation kinetics of lutein content, total phenolic content, and total antioxidant activity were evaluated, yielding activation energy values of 34.03, 61.89, and 63.55 kJ/mol, respectively. Lutein degradation followed a second-order kinetic model, changes in total phenolic content adhered to a zero-order kinetic model, and total antioxidant activity followed a first-order kinetic model. Considering the Q10 values, it was determined that the effect of increasing the temperature from 80 degrees C to 90 degrees C was less significant than the effect of increasing the temperature from 90 degrees C to 100 degrees C on all bioactive components.