Nutritional quality of extra virgin olive oil determined by the application of a new functional matematic index

Abstract

The extra virgin olive oil is very important in the Mediterranean diet. From the nutritional point of view, the high energy content and an optimal ratio between saturated and unsaturated fatty acids, together with the presence of minor compounds such as phenols and tocopherols and the related antioxidant capacity, confer to this product a high healthy value.The extra-virgin oil’s nutritional properties depend on the pedoclimatic conditions, cultivar and the production process. In the last years many studies have been performed to remark and describe the safety and nutritional quality of the extra-virgin olive oils but it is difficult to compare different parameters representative of oil’s nutritional quality and to establish which of them is more important to define the nutritional value of an oil. In 2007, Finotti and colleagues developed a Functional Mathematic Index (FMI) in order to quantify the nutritional quality of extra virgin olive oil. This index is important because it is able to convert a concept as the quality into a numeric quantity. The FMI takes into account different nutritional,antioxidant and chemical parameters representative of oil properties.These parameters, suitably processed with the FMI Workbench free software, provide a unique value indicated as global quality index (IGQ). We have calculated both the global FMI and the local FMIs. Aim of this study is to compare the nutritional properties of extra virgin olive oils from different olive varieties, Biancolilla and Oglialora grown in Sicily, by the functional mathematic index. Samples of extra-virgin olive oils from two different cultivar (Biancolilla, Oglialora) and processed by different extraction methods (continuous cycle and hydraulic press) have been analyzed. The drupes are grown in the same climatic conditions. The parameters analyzed to calculate the FMI have been divided in three groups which are related to chemical, nutritional, technologic properties of oil. The results of the analyses were processed by the software and the IGQ and LQ of each oil sample have been compared in order to define which of them had the better nutritional properties. The analyses allow to classify all oil samples as extra-virgin olive oils. All parameters are within the limits of the Italian (E.U.) law. No difference among two cultivars about acidity, peroxide number and fatty acids profile was found. The lipofilic antioxidant capacity was higher in Biancolilla variety than in Oglialora with both extractive methods,sample oils extracted with continuous method have shown a lower of 16% content of tocopherols for both variety.The FMI of all oil samples varies from 0.27 to 0.34, therefore they satisfy the necessary conditions to be considered high quality extra-virgin oil; Nonetheless, the cultivar Biancolilla has shown a global index better than the Oglialora. From the study of local FMI we observed that the nutritional quality of oils extracted by continuous cycle is penalized in the total polyphenols and lipofilic antioxidant capacity parameters. The FMI allows to detect that the Biancolilla variety is better than Oglialora and then to underline which parameter can be modified in order to increase the nutritional quality of the oil analyzed.