| Abstrakt: |
In this study, the effect of hot oven drying condition (drying temperature and time) on weight loss, total phenolic compounds and antioxidant properties of mint leaf was investigated and optimized by response surface methodology . The results showed that with increasing drying time and temperature, weight loss and total phenolic compounds of mint leaves increased and drying time had more effect on changes of these two parameters compared to drying temperature. Total phenolic compounds of samples increased with increasing drying time, but with increasing drying temperature at the beginning of the process, the amount of total phenolic compounds of samples increased. The DPPH radical scavenging activity of the samples decreased by increasing the drying time (up to 176 min) and then increased with increasing the drying time. The results showed that applying drying temperatures up to 50 °C increased DPPH scavenging activity and higher drying temperatures resulted in a decrease in DPPH scavenging activity of the samples. Increasing the drying time and temperature reduced the antioxidant capacity and ferric reducing power (FRAP) of the samples, which the slope of the changes in the FRAP and antioxidant capacity of the samples with the changes in drying time is more severe than the drying temperature changes . The best conditions for hot oven drying of mint leaves are using drying temprature of 59.91 °C for 52 minutes and by applying the optimal conditions, the amount of weight loss, total phenolic compounds, and DPPH scavenging percentage of produced dry mint were 69.98%, 6.90 mg/gram of dry weight, 89.68% respectively and the desirability of this optimal condition was 0.746. The results of optimal conditions validation in real conditions are very similar to the results related to the predicted optimal conditions by response surface methodology [ABSTRACT FROM AUTHOR] |
