Ripening and storage conditions of Chétoui and Arbequina olives: Part I. Effect on olive oils volatiles profile.

The distinctive aroma of virgin olive oil is mainly attributed to its volatile profile including components responsible for positive attributes and others for sensory defects resulting from chemical oxidation and exogenous enzymes. For this reason, the evolution of volatile compounds from Chétoui and Arbequina virgin olive oils during olive ripening and storage (at 4 and 25 °C during 4 weeks) was investigated. The profile of volatile phenols during olive storage was also studied. Quantitative differences in the volatile compounds during olive storage at 4 and 25 °C according to olive cultivar was determined. Concerning the volatile phenols, the Arbequina olives were the most affected by high storage temperature, as the formation of these compounds, especially 4-ethyl and 4-vinyl derivatives of phenol and guaiacol were more noticeable in Arbequina oils extracted from stored fruits at 25 °C.

Ripening and storage conditions of Chétoui and Arbequina olives: Part II. Effect on olive endogenous enzymes and virgin olive oil secoiridoid profile determined by high resolution mass spectrometry.

Several factors affect virgin olive oil (VOO) phenolic profile. The aim of this study was to monitor olive hydrolytic (ß-glucosidase) and oxidative (peroxydase, POX, and polyphenoloxydase, PPO) enzymes during olive ripening and storage and to determine their capacity to shape VOO phenolic profile. To this end, olives from the cultivars Chétoui and Arbequina were stored at 4°C or 25°C for 4weeks and their enzymatic activities and oil phenolic profiles were compared to those of ripening olives. We observed different trends in enzymes activities according to cultivar and storage temperature. Secoiridoid compounds, determined by high resolution mass spectrometry (HRMS), and their deacetoxylated, oxygenated, and deacetoxy-oxygenated derivatives were identified and their contents differed between the cultivars according to olive ripening degree and storage conditions. These differences could be due to ß-glucosidase, POX and PPO activities changes during olive ripening and storage. Results also show that oxidised phenolic compounds could be a marker of VOO ''freshness".

Monitoring endogenous enzymes during olive fruit ripening and storage: correlation with virgin olive oil phenolic profiles.

The ability of olive endogenous enzymes ß-glucosidase, polyphenol oxidase (PPO) and peroxidase (POX), to determine the phenolic profile of virgin olive oil was investigated. Olives used for oil production were stored for one month at 20 °C and 4 °C and their phenolic content and enzymatic activities were compared to those of ripening olive fruits. Phenolic and volatile profiles of the corresponding oils were also analysed. Oils obtained from fruits stored at 4 °C show similar characteristics to that of freshly harvested fruits. However, the oils obtained from fruits stored at 20 °C presented the lowest phenolic content. Concerning the enzymatic activities, results show that the ß-glucosidase enzyme is the key enzyme responsible for the determination of virgin olive oil phenolic profile as the decrease in this enzyme activity after 3 weeks of storage at 20 °C was parallel to a dramatic decrease in the phenolic content of the oils.