Effect of drying methods on chemical composition and antioxidant activity of underutilized stinging nettle leaves

Stinging nettles provide low-cost quality nutrition for alleviating malnutrition. Previous research on stinging nettles focused mainly on the nutritional quality of fresh leaves. In this study, the effect of drying method on macronutrients, mineral content, ascorbic acid, β-carotene content and total phenols content and antioxidant activity were investigated. The contribution of fresh, oven dried or freeze dried stinging nettle leaves to the required daily value for the nutrients were also determined. Oven drying of nettle leaves resulted in a higher loss of β-carotene and ascorbic acid content compared to freeze drying. In contrast, the total phenols content and total antioxidant activity were higher in oven dried stinging nettle leaves compared to freeze dried leaves. Overall, freeze dried and oven dried nettle leaves can be considered as a rich source of Ca, Mg and vitamin A; a good source of vitamin C, Fe, and Mn; and a source for Mg and K. Stinging nettle leaves could potentially be used as a cheap natural source of antioxidants and for addressing micronutrient malnutrition.