Chemometric discrimination of Turkish olive oils by variety and region using PCA and comparison of classification viabil
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ORIGINAL PAPER
Chemometric discrimination of Turkish olive oils by variety and region using PCA and comparison of classification viability of SIMCA and PLS‑DA Onur Özdikicierler1 Received: 27 May 2020 / Revised: 9 September 2020 / Accepted: 13 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Virgin olive oil samples of eight varieties from four regions (North Aegean, South Aegean, Mediterranean, and Southeastern) of Turkey were discriminated using fatty acid and sterol composition. Principle component analysis represented a separation of South Aegean olive oils from the rest of the sample groups, that mainly depend on Stigmasterol, β-sitosterol, Δ5,24-Stigmastadienol, Δ7-Avenasterol, C17:0, and C17:1 variables. Except few overlaps, North Aegean samples were also discriminated with Mediterranean and Southeastern samples. The varietal separation was not interpretable by itself but since all samples from South Aegean region were Memecik variety, regional separation has become clearer. Soft independent modeling of class analogy shows good separation between North and South Aegean samples with only a few exceptions. The number of misestimated samples was high at Mediterranean and Southeastern models on Coomans’ plots because of high variance within each group. Partial least squares discrimination analysis was more successful than Soft independent modeling of class analogy. The prediction capabilities of South Aegean and North Aegean models were better than others. Root mean squared error of prediction and goodness of prediction were 0.092 and 0.961 for South Aegean, 0.182, and 0.853 for North Aegean, respectively. Unlikely to soft independent modeling of class analogy, Southeastern and Mediterranean samples were not rejected but remained as “uncertain” on partial least squares discrimination analysis with the help of its algorithm. Keywords Olive oil · Sterol composition · Fatty acid composition · PCA · SIMCA · PLS-DA
Introduction Olive oil has been an emblematic product for the producing countries and has gained an increasing worldwide reputation due to its sensorial and nutritional properties last few years. Because the growth of olive fruit is highly climatedependent, most of the olive and olive oil production in the world is carried out by countries that have a coast to the Mediterranean Sea. Over the past few decades, public awareness of olive oil authenticity has increased because of its vulnerability to economically motivated adulteration and/or mislabeling which has great importance not only for olive oil producers, retailers, and consumers but also for lawmakers * Onur Özdikicierler [email protected] 1
Food Engineering Department, Faculty of Engineering, Ege University, Bornova, İzmir, Turkey
and regulators. To meet the demands and the quality expectations of consumers, producers focus on highlighting the authentic properties of the product such as variety and geographical origin of olive oil [1]. As the value of the olive oils with specific features incr
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