Quality and nutritional properties of hazelnut (Corylus avellana L.) oil and defatted flours

The aim of this study was the characterization of some samples of partially - defatted hazelnut (Corylus avellana L.) flours and the cold-pressed hazelnut oils. The partially-defatted hazelnut flours (from un-roasted and roasted seeds) showed interesting nutritional properties, particularly concerning branched amino acid composition (1.67, 2.45 and 1.31 g/100 g, for valine, leucine and isoleucine respectively, high roasted flour, fresh weight). Glutamic acid was the main amino acid recovered both in un-roasted and roasted flours. The trend of acidification and peroxidation of flours during the shelf life (evaluated up to 6 months) showed that these products are quite stable if stored at room temperature (25°C) in the dark. The oil composition confirmed a strong impact of roasting practice on the vitamins fraction; alfa-tocopherol content showed a decrease of 19.5% after roasting. We suggest improving the use of hazelnut-related products, because of their significant nutritional properties. Moreover, we highlight that roasting practices can decrease the content of some bioactive nutritional compounds, like tocopherols.