Chemical Changes Occur in Extra-Virgin Olive Oil during Fruits Ripeness of Zalmati Cultivar Planted in Warm Desert Climate

Abstract

The evaluation of the impact of olive ripening degree on the stability of extra virgin olive oils not only by determining the oxidative stability index, the 1-diphenyl-2-picrylhydrazyl (DPPH) radical test, but also by studying the variation of their sensory profiles, plays a key role in the assessment of the overall olive oil quality. To this end, Zalmati extra virgin olive oils samples were taken at three harvest dates relating to three ripening stages. The obtained results revealed that several analytical parameters, namely free fatty acids, peroxide index, K₂₃₂ and K₂₇₀, augment during repining. Besides, a substantial reduction was noticed for the monounsaturated fatty acid, chlorophyll, and carotenoids in oils produced at the advanced ripening stage. Principal component analysis (PCA) was employed to the data of the analytical analysis to delve into their capacity for discerning the oil quality consistently with the harvesting period of the Zalmati olives. Familiar plots have indicated that different olive oils are categorized in diverse harvest period groups, each of which could be obviously recognized.

graphical abstract