Kornsteiner, M., K.H. Wagner, I. Elmadfa, 2006. Tocopherols and total phenolics in 10 different nut types. Food Chemistry. 98:381-87.
The study was conducted to assess the content of tocopherols (α-, β-, γ- and δ-) and carotenoids (α- and β-carotene, zeaxanthin, lutein, cryptoxanthin and lycopene) in the unsaponifiable matter as well as the amount of total phenols of 10 different types of nuts. Tocopherols and carotenoids were analyzed with HPLC, total phenols photometrically. The mean value of α-tocopherol equivalents ranged from non-detectable (macadamias) to 33.1 mg/100 g extracted oil (hazelnuts). Among all nuts, almonds and hazelnuts had the highest mean α-tocopherol content (24.2 and 31.4 mg/100 g extracted oil, respectively). β- and γ-tocopherols were prevalent in Brazil nuts, cashews, peanuts, pecans, pines, pistachios and walnuts. Mean values oscillated between 5.1 (cashews) and 29.3 (pistachios). Traces of δ-tocopherol (<4 mg/100 g extracted oil) were analyzed in cashews, hazelnuts, peanuts, pecans, pines, pistachios and walnuts. There were no carotenoids detected in the tested nuts with the exception of pistachios. The mean content of total phenolics varied between 32 mg gallic acid equivalents/100 g (pines) and 1625 mg (walnuts). The results show the eterogenic amounts of antioxidants in nuts, which emphasizes the recommendation of a mixed nuts intake.