Lipid profile of nuts and oilseeds

Total fat and fatty acids profile are important factors for the nutritional evaluation of nuts and oilseeds. In the last years, several studies have reported the importance of consumption nuts and oilseeds to promote health benefits, especially those related with cardiovascular diseases. This is due to its high content of fat, which is mainly composed of unsaturated fatty acids. The overall objective of this study was to compare the total fat content and fatty acids profile of seven types of nuts and five types of oilseeds. Thereby, samples were randomly collected at supermarkets and herbal shops from Lisbon region, and three composite samples were prepared, in order to provide accurate data that covers all the possible variations among samples. For the lipid profile of oilseeds and nuts, either accredited methods or methods for which the laboratory has shown a successful participation in Proficiency testing schemes were used. Total fat determination was performed with an acid hydrolysis method followed by extraction using a Soxhlet apparatus with petroleum ether, as the extraction solvent (AOAC 948.15, 2000). Preparation of FA methyl esters was carried out by a combined method of methylation and transesterification. Chromatographic analysis was performed with a gas chromatograph equipped with a mass spectrophotometer detector. A HP-88, fused silica capillary column (100 m x 0.25 mm i.d., 0.25 mm) was used for FA determination. Samples were analyzed in triplicate. The applied GC-MS method allows separation and identification of more than fifty FA, including some trans-FA and ω3 or ω6 FA. Total fat content ranged between 39.8 ± 1.15 and 66.6 ± 0.11 g/100 g of edible portion, for brown flaxseeds and Brazil chestnuts, respectively. Linoleic acid was the major fatty acid found in sunflower seeds and walnuts. Sesame seeds, pumpkin seeds, roasted peanuts and salted peanuts have similar quantities of oleic and linoleic acid. For brown and golden flaxseeds, the major fatty acid was linolenic acid (18.3 ± 1.99 and 21.8 ± 1.03 g/100 g of edible portion, respectively). Cashew, peeled almonds and salted pistachio have similar fatty acids profile with oleic acid being the major fatty acid. Nuts and oilseeds are rich sources of fat, specially unsaturated fatty acids which are related with several health benefits, namely cardiovascular diseases. In Portugal, circulatory system diseases still remain the leading cause of death. Therefore, increasing the consumption of nuts and oilseeds in Portugal is extremely required. With this study we intend to provide accurate data on nuts and seeds lipid profile to enhance its consumption based on its nutritional quality and related health benefits. Further studies will be carried out with respect to phytosterols composition, carotenoids and liposoluble vitamins.