Influence of Drying Process on the Functional Properties of Some Plants

Four green leafy vegetables of Apiaceae family, celery (Garveolens var. Dulce Apium), coriander (Coriander sativum), dill (Anethum garveolens), and parsley (Crispum petroselinum) were used to assess the effect of different drying methods on the antioxidant capacity. The edible parts of these plants were dried in air, convective oven and microwave oven, extracted with methanol. Moisture, total phenols, carotenoids, chlorophyll content and antioxidant capacity were determined in fresh as well as in the dried samples. Fresh plants were characterized with the highest contents of all tested parameters followed by air dried then oven dried and finally microwave dried herbs. Moisture content ranged from 83.40 to 88.32% in fresh parsley and coriander, respectively. Dried samples with different methods showed moisture content between 5.88in dill and 7.49% in coriander. The highest antioxidant capacity was recorded in fresh coriander (80.44%). Total phenol content of tested plants ranged from 0.38 mg gallic acid/g in microwave dried dill to 1.3 mg gallic acid /g in fresh celery. Total carotenoids content was highly affected with the drying process recording the lowest values in microwave dried dill, coriander and celery (13.1, 14.0 and 14.3mg/kg, respectively). The highest loss of chlorophylls was found in microwave dried coriander (87.5%) compared to the fresh state. The results indicated that air drying at room temperature is the most efficient drying method followed by oven drying at 70°C when conserving the beneficial bioactive components was considered. Keywords: Antioxidants; drying; medicinal plants; pigment