Effect of air drying temperature on the phenolics and antioxidant activity of Xuan-Mugua fruit

Xuan-Mugua is a Chinese traditional fruit and is mainly preserved by air drying. To explore the effect of temperature on the drying property and quality of the fruits, they were sliced and dried at 60-90 °C. The results indicated that the drying time shortened from 150 to 80 min with the increasing temperature and the minimal time was found at 90 °C. The total phenolic content and antioxidant activity generally decreased by 5.09-18.27% at higher temperature (90 °C) and their maximums respectively appeared at 60 and 80 °C. Compared with the medium temperatures (60 and 70°C), the phenolic profiles changed obviously at higher temperatures (80 and 90 °C), and a transformation of chlorogenic acid was detected; besides, with the increasing temperature, the main phenolics including catechin and chlorogenic acid respectively decreased by 29.3% and 18.4%. Taking the above findings together, 70 °C should be the proper temperature to dry Xuan-Mugua fruits.