Mineral Properties and Dietary Value of Raw and Processed Stinging Nettle (Urtica dioica L.)

Stinging nettle (Urtica dioica L.) has a long history of usage and is currently receiving attention as a source of fiber and alternative medicine. In many cultures, nettle is also eaten as a leafy vegetable. In this study, we focused on nettle yield (edible portion) and processing effects on nutritive and dietary properties. Actively growing shoots were harvested from field plots and leaves separated from stems. Leaf portions (200？g) were washed and processed by blanching (1？min at 96–98°C) or cooking (7？min at 98-99°C) with or without salt (5？g· ). Samples were cooled immediately after cooking and kept in frozen storage before analysis. Proximate composition, mineral, amino acid, and vitamin contents were determined, and nutritive value was estimated based on 100？g serving portions in a 2000 calorie diet. Results show that processed nettle can supply 90%–100% of vitamin A (including vitamin A as β-carotene) and is a good source of dietary calcium, iron, and protein. We recommend fresh or processed nettle as a high-protein, low-calorie source of essential nutrients, minerals, and vitamins particularly in vegetarian, diabetic, or other specialized diets. 1. Introduction Stinging nettle (Urtica dioica L.) has a long history as one among plants foraged from the wild and eaten as a vegetable [1, 2]. Although not fully domesticated, the species remains popular even in the current era for food and medicine as reported, for example, in Nepal [2] and Poland [3]. Despite U. dioica being recognized as an edible and highly nutritious vegetable, research attention has focused more on its value as a source of alternative medicine and fiber. Clinical trials have confirmed the effectiveness of nettle root and saw palmetto (Serenoa repens (Bart.) Small) fruit extracts in the treatment of benign prostatic hyperplasia [4]. Dried nettle leaf preparations are also known to alleviate symptoms associated with allergic rhinitis [5], and a technology for granulating lipophilic leaf extracts for medicine has been developed [6]. A recent report from ongoing work in Italy confirms the potential of U. dioica as a sustainable source of textile fiber [7]. There are a number of reports that address the role of U. dioica in human nutrition. Fatty acid and carotenoid content in leaf, stem, root, and seed samples have been measured [8], and the properties of phenolic compounds in leaves, stalks, and fibers have been reported [9]. Furthermore, the quality and safety [10] and microbiological properties [11] of sucuk, a Turkish dry-fermented sausage, incorporating dried U. dioica leaf have