Olive fruit and leaves have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers. The present research was achieved on Tunisian olive flowers. It aimed at studying the effects of flower development on phenolic compounds and antioxidant activity. The extracts were analyzed using high performance liquid chromatography coupled to diode array detection (HPLC/DAD) and coupled to mass spectrometry (LC-MS/MS). The HPLC/DAD analysis indicated that oleuropein aglycon (from 1.158 to 3.746 g/kg), followed by hydroxytyrosol (from 0.168 to 1.581 g/kg) and oleoside (from 0.143 to 1.325 g/kg) were the predominant phenolics in olive flowers extracts during development stages. Twenty compounds have been identified, revealing the complex profile of olive flowers, composed, in order of abundance, by secoiridoids, phenolic alcohols, lignans, flavonoids and phenolic acids. Total phenolic contents increased from 2.455 to 8.541 g/kg Gallic acid equivalent per kg of fresh flowers during all steps of the flower development. A correlation between antioxidant activity and total phenolic contents was determined.

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Given the importance of olive oil as a food product worldwide and given the exposure of many productive olive orchards to many pollution sources, this work is a contribution to the clarification of atmospheric metal pollution effects on the quality of olive oil and its possible toxicity for human beings. This work is carried out on olive orchards (Olea europaea L., cv. Chemlali) situated in a polluted region close to a fertilizer factory and in a controlled, unpolluted area, managed with comparable cultivation techniques during two successive years (2015/2016 and 2016/2017). Pollution negatively affects the oxidative stability and nutritional value of olive oil, especially by decreasing the contents of antioxidant compounds and the fatty acid composition. Atmospheric metals are confirmed to have a negative effect on olive oil chemicals; oils show a disruption of their squalene, tocopherols, and triglyceride composition in comparison with control oils. Practical Applications: This study is carried out in two olive orchards (Olea europaea L., cv. Chemlali) located in a polluted area near a fertilizer factory and in a control unpolluted site, managed with similar cultivation techniques. The aim is to investigate the physiological and biochemical responses of polluted oils (PO), exposed to atmospheric metal contamination as compared to control oils (CO). The results of this study emanate from the accidental exposure to contamination sources, such as the direct contact of olives, with an elevated polluted environment that might be made more severe by gaseous air pollutants emitted by the factory. Then, air contamination avoidance from factories should be examined together with any possible probable methodologies to decrease plant tissue contamination. The SIAPE is the main pollution source in Sfax city. Vegetation developed around the city is continuously exposed to air pollution. Therefore, olive fruits are contaminated by the chemical pollution which affects the quality of olive oils.