Determination of Sterol and Fatty Acid Compositions, Oxidative Stability, and Nutritional Value of Six Walnut (Juglans regiaL.) Cultivars Grown in Portugal
Six cultivars (Franquette, Marbot, Mayette, Mellanaise, Lara, and Parisienne) of walnuts (Juglans regia L.) were collected during the 2001 crop, from Bragança, Portugal. Chemical composition,
including moisture, total oil content, crude protein, ash, carbohydrates, and nutritional value, was
evaluated. Fat was the predominant component, ranging from 62.3 to 66.5%. Total oil was extracted
and analyzed for fatty acids, sterols, oxidative stability, and peroxide value. Fatty acids and sterols
were determined by gas-liquid chromatography coupled to a flame ionization detector. Eighteen
fatty acids were quantified. Polyunsaturated fatty acids and, in particular, linoleic acid were
predominant. â-Sitosterol, ¢5-avenasterol, and campesterol were the major sterols found. Differences
were observed among the studied cultivars, especially in peroxide values and in the sterol profile.