Effect of Drying Methods on the Antioxidant Capacity and Bioactive and Phenolic Constituents in the Aerial Parts of Marjoram (Origanum majorana L.) Grown Naturally in the Taurus Mountains in the Mediterranean Region

This research revealed the effect of drying processes on the bioactive properties of marjoram leaves. The total carotenoid content in marjoram leaves ranged between 60.96 µg/g (fresh) and 189.78 µg/g (oven-dried), whereas the total flavonoid content ranged between 949.33 mg CE/100 g (control) and 16,958.59 mg CE/100 g (oven-dried). The total phenolic amounts in marjoram leaves were between 259.17 mg GAE/100 g (fresh) and 1264.17 mg GAE/100 g (oven-dried), while the antioxidant activity values were between 45.23% (fresh) and 77.29% (oven-dried). The 1,2-dihydroxybenzene and (+)-catechin amounts in marjoram leaves were between 19.54 (microwave-dried) and 165.26 (oven-dried) to 20.97 (fresh) and 46.99 mg/100 g (oven-dried), respectively. The kaempferol content in the marjoram plant was specified between 11.45 mg/100 g (fresh) and 43.05 mg/100 g (oven-dried). In general, the quantities of phenolic constituents in the marjoram leaves dried in both drying systems increased compared with fresh samples (except 1,2-dihydroxybenzene, p-coumaric acid, and resveratrol in the microwave-dried samples).