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Analytical Approaches for the Quality and Food Safety assessment of Olive Oil: Volatile Organic Compounds profiles, Antioxidants and Phthalates content monitoring
Publication . Freitas, Flávia Sofia Salgado de; Silva, Marco; Cabrita, Maria João
In the plant kingdom, many fruits and seeds provide edible oils. However, olive oil,
often referred to as "liquid gold," is the most important and widely used in the Mediterranean
diet. Its nutritional value is considered to be twice that of cereals and ten times greater than
that of wine. It is estimated that approximately 3 million tons of olive oil are consumed worldwide every year.
This doctoral thesis focused on the study of olive oil, addressing three main themes
aimed at deepening the understanding of this food matrix, from its chemical composition to
the factors affecting its quality and safety.
The first theme investigated the evolution of volatile organic compounds throughout
the shelf life of olive oil, focusing on markers associated with positive attributes and sensory
defects. A robust method was developed using solid-phase microextraction in headspace
mode (HS-SPME), coupled with gas chromatography and mass spectrometry (GC/MS). This
method allowed the identification of significant variations in the levels of volatile organic compounds (VOCs), particularly those derived from the lipoxygenase (LOX) pathway, over time.
Principal component analysis (PCA) revealed a clear distinction between the volatile profiles of
extra virgin olive oils and deteriorated oils. The relationship between
E-2-hexenal and acetic
acid proved to be a potential indicator for predicting the sensory disqualification of olive oil
based on the evolution of volatile compounds during storage.
The second theme explored the potential of olive oil as a nutraceutical product, em-
phasizing the antioxidants hydroxytyrosol and tyrosol, both recognized for their health-promoting properties. A method was developed to efficiently extract these compounds from the
by-products of olive oil production. These compounds were concentrated and added to the
final olive oil, resulting in enriched olive oil and a concentrated antioxidant extract with functional applications.The third theme focused on the presence of plasticizers in olive oil, aiming to identify
and quantify phthalate esters. Through a critical review, various analytical methods used for
quantifying phthalates in olive oils and wines were evaluated, discussing analytical challenges
and mitigation strategies. Additionally, a study was conducted to monitor contamination by
plasticizers, including 23 phthalates and 9 phthalate substitutes, throughout the olive oil production and storage process. Using liquid-liquid extraction with hexane/methanol and analysis
by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS), with detection
limits ranging from 0.001 to 0.103 mg/kg, it was observed that plasticizer levels progressively
increased as olive oil went through production stages. The main sources of contamination were
identified, highlighting the importance of minimizing plastic use along the production line and
during storage. Diisononyl phthalate (DINP) was the most prevalent compound, found at concentrations exceeding the migration limits established by the European Union in some olive
oils.
The results presented in this thesis contribute to a deeper understanding of the quality,
safety, and functional potential of olive oil, offering practical solutions to optimize its production and preservation, as well as promoting its valorization as a high-value-added food product.
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Fundação para a Ciência e a Tecnologia
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OE
Número da atribuição
2020.08089.BD