Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut

Nuts are high in fat but have a fatty acid profile that may be beneficial in relation to risk of coronary heart disease. Nuts also contain other potentially cardioprotective constituents including phytosterols, tocopherols and squalene. In the present study, the total oil content, peroxide value, composition of fatty acids, tocopherols, phytosterols and squalene content were determined in the oil extracted from freshly ground walnuts, almonds, peanuts, hazelnuts and the macadamia nut. The total oil content of the nuts ranged from 37.9 to 59.2%, while the peroxide values ranged from 0.19 to 0.43 meq O₂/kg oil. The main monounsaturated fatty acid was oleic acid (C18:1) with substantial levels of palmitoleic acid (C16:1) present in the macadamia nut. The main polyunsaturated fatty acids present were linoleic acid (C18:2) and linolenic acid (C18:3). α-Tocopherol was the most prevalent tocopherol except in walnuts. The levels of squalene detected ranged from 9.4 to 186.4 μg/g. β-Sitosterol was the most abundant sterol, ranging in concentration from 991.2 to 2071.7 μ g/g oil. Campesterol and stigmasterol were also present in significant concentrations. Our data indicate that all five nuts are a good source of monounsaturated fatty acid, tocopherols, squalene and phytosterols.