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The influence of semi-hard (C1), hard (C2), and soft whey cheese (C3) immersed in extra virgin olive oil (EVOO) on its oxidative and hydrolytic parameters, fatty acids, and phenolic composition during two months of simultaneous storage was investigated. Accelerated hydrolytic and oxidative degradation was noted in EVOO stored with the immersed cheese compared to control oil. Oxidation indicator (K232), myristic (C 14:0), and trans-oleic fatty acid (C18:1t) exceeded the prescribed limit for the EVOO category in oils stored with immersed C1 and C2, which indicated that standard analytical parameters are ineffective as tools to examine the declared quality and authenticity of such topping oils. The noted changes in fatty acid profile were primarily prescribed to the migration of fats. C1 and C2 influenced a comparable reduction in EVOO total identified phenolic content (−92.1% and −93.5%, respectively), despite having a different content of total proteins and moisture, whereas C3 influenced a slightly lower reduction (−85.0%). Besides the protein profile, other cheese compounds (e.g., moisture, carbohydrates) have been shown to have a considerable role in the development of the EVOO phenolic profile. Finally, compositional changes in EVOO used as a medium for cheese preservation are under significant influence of the cheese’s chemical composition.

The present study investigated the changes in extra virgin olive oil (EVOO) quality, health, and flavour properties during simulated domestic consumption conditions in which the EVOO bottles were reopened daily, thereby gradually increasing the headspace. Quality parameters, phenolic and volatile compounds, and sensory attributes of two monovarietal EVOOs, Istarska bjelica (IB) and Buža (B), have been evaluated every seven days for one month. After storage, the total phenolic content decreased by 12.3% and 17.6% in IB and B EVOOs, respectively, while the total concentration of volatile compounds decreased by approximately 19%. However, the results have shown that no enhanced degradation of phenolic and volatile compounds has been noted in EVOOs stored under consumption conditions compared to the ones stored unopened during the same period, implying that the degradation degree was predominantly attributed to oil aging. The principal component analysis emphasised peroxide value and sensory attributes as parameters that segregated EVOOs under consumption conditions from the fresh and unopened ones. Furthermore, the conditions in which EVOO was consumed in a recommended daily dosage (20 g) during one-month storage did not reduce its phenolic content under the levels required for the EFSA health claim application.

The purpose of this study was to evaluate the compositional changes (quality parameters, fatty acids, phenolic compounds, and antioxidant capacity) in extra virgin olive oil (EVOO) after cooking treatment in realistic domestic conditions (roasting at 180 °C/60 min) with the addition of typical Mediterranean vegetables (potato, carrot, onion, and mix of those vegetables in equal proportions). Heating increased oil oxidation parameters, while the addition of vegetables during roasting reduced the degree of oil secondary oxidation. EVOO fatty acids have shown strong resistance to heating regardless of the vegetable species added. The initial phenolic composition and radical-scavenging activity of EVOO were significantly altered after roasting resulting in a particular response, depending on the vegetable species used in the treatment. In the presence of vegetables, olive oil total identified phenolic content suffered a major loss, with only 28.27%, 22.00%, 19.87%, and 19.03% of the initial content being preserved after roasting with carrots, potato, onion, and mixed vegetables, respectively. A considerable correlation of both moisture content and pH of the vegetables and the evaluated parameters was found. Obtained results might contribute to understanding the fate and preservation of EVOO beneficial composition in the course of the real cooking conditions.