CODA · Classification of Olive Oils and Detection of Adulteration

Final Activity Report Summary - CODA (Classification of Olive Oils and Detection of Adulteration)

The European Union (EU) created protected designation of origin system to encourage diverse agricultural production, to protect product names from misuse and imitation and to help consumers by giving them information concerning the specific characteristics of the product. With increasing demand to olive oil, special types of olive oils generally produced from olives coming from certain regions (monovarietal) have been appeared on the market. Determining compositional differences between olive oils produced from various varieties of olives and from different growing locations is the first step towards establishing geographical indication status. For many olive producing regions in EU olive and olive oil is the main source of employment and economic activity. Turkey produces about 1.2 million tons of olive on years and 250 thousand Turkish families work for olive and olive oil production. Turkey has been known as one of the earliest cultivation area for olive and there are important indigenous varieties growing in various parts of the country. In this project, characterisation of Turkish monovarietal extra-virgin olive oils obtained from various varieties of olives (Ayvalik, Gemlik, Memecik, Erkence, Nizip and Domat) growing in different locations of Aegean coastal region of Turkey in two harvest years was performed by routine chemical analysis (free fatty acid value, peroxide value, total phenol content and colour) and fatty acid, phenol and mid-infrared spectral profile. Same analyses were also performed for commercial olive oils obtained from north and south Aegean coastal regions. Data obtained from characterisation studies was used in the classification of olive oils with respect to olive variety, growing location and harvest year. Multivariate statistical data analysis techniques such as principal component analysis and partial least square analysis were used to evaluate the analysis results. These types of studies are important to determine the factors affecting the olive oil composition as well as geographical indication regulations. It was determined that olive variety, growing location and harvest year have significant effect on olive oil composition and fatty acid composition is very effective in classification of olive oils with respect to these parameters. In addition, a correlation was tried to be established between standard chemical analysis results and mid-infrared spectral data. It was found that free fatty acid value and major fatty acids of olive oils could be accurately predicted with mid-infrared spectroscopy at the same time without any sample preparation step. Another objective of the project was to detect the adulteration of olive oils with various adulterants using quick mid-infrared spectroscopy incorporation with chemometric techniques. This spectroscopic technique was very effective in determining monovarieatal olive oil mixing as well as adulteration with single (hazelnut, cottonseed and rapeseed oils) and binary mixtures (cotton-sunflower oils) of edible oils at low levels. Detection limit for mixture of two monovarietal olive oils was 5-10 % depending on olive variety. With mid-infrared spectroscopy, presence of hazelnut, cottonseed, rapeseed and corn-sunflower oils in olive oil could be determined at 15, 5, 5 and 5 % levels, respectively. All the goals established at the start of the project were completed successfully. This project funded by International Reintegration Grant was quite helpful for researcher's integration to host institute. A needed infra-structure was set up to continue her scientific career. Two post-graduate students worked in the project. Findings of the study resulted in scientific publications and scientific meetings attended were great value to exchange views with other scientists and follow the progress in her area.

Data: CORDIS, © European Union