Chemical composition changes in four green olive cultivars during spontaneous fermentation

- Sugars and phenolics contents in fermentation brines depend on the olive cultivar.
- The daily decrease of the phenolic content in olives rates varied from 2% to 6%.
- The phenolics overall reduction ranged from 40 to 63% depending on the cultivar.
- Hydroxytyrosol was the main simple phenolic compound identified in all brines.
- Brines of Moroccan and Languedoc Picholine showed the highest antioxidant activity.

Changes in some physico-chemical characteristics (pH and free acidity) and chemical composition (sugars, total phenolic and flavonoid contents) of four olive cultivars during spontaneous fermentation in brine were investigated. The cultivars were typical of the Moroccan market: “Moroccan Picholine”, “Languedoc Picholine”, “Ascolana” and “Sevillana”. The physico-chemical changes of olives and brines during fermentation process were monitored. A similar pattern of pH was noticed for the “Moroccan Picholine”, “Languedoc Picholine” and “Ascolana” cultivars with a final pH ranging between 4.4 and 4.6. The profile of free acidity measured throughout fermentation period in brines was in agreement with the pH trend. The concentration of sugars, total phenolic and flavonoids contents in olives flesh and brines during fermentation is reported. The loss of flavonoids, sugars and total phenolic contents in the olive flesh by the end of fermentation process was up to 60%, 63% and 79% in “Languedoc Picholine”, “Sevillana” and “Moroccan Picholine”, respectively. The main phenols identified and quantified in the different brines at the end of brining process were hydroxytyrosol, tyrosol, (+)-catechin and quercetine. The highest total phenolic content and antioxidant activity were obtained in Moroccan Picholine brine after 71 days of fermentation.