Olive (Olea europaea L. cv. Galega vulgar) seed oil: a first insight into the major lipid composition of a promising agro-industrial by-product at two ripeness stages

Abstract

Olive seeds are promising industrial by-products whose study acquires relevance both for valuing their biotechnological potential and for discriminating the origin and/or the edaphoclimatic conditions of olives. Herein, the fatty acid (FA) and triacylglycerol (TAG) profiles of total lipid extracts and neutral lipid fractions from olive seeds (Olea europaea L. cv. Galega vulgar), at two ripeness stages, were analysed by mass spectrometry (MS)-based approaches.

In both olive seeds (green and ripe), the predominant FA were C_18:1(n-9) (56%), C_18:2(n-6) (17%) and C_16:0 (18%). The seeds also contained the essential FA C_18:3(n-3) (0.11%). Ripeness led to a decrease of saturated FA and an increase of unsaturated FA. In total lipid extracts, major FA (C_18:1(n-9) and C_18:0) could distinguish green from ripe olives (p < 0.05). In neutral lipid fractions, besides major FA (C_18:1(n-9) and C_16:0), minor ones (C_14:0, C_18:3(n-3), C_20:0 and C_22:0) could distinguish ripeness stages (p < 0.05). The relative amount of nine TAG was significantly different between green and ripe olives (p < 0.05), of which six were minor TAG.

Olive seeds and their oil are a good source of n-9 monounsaturated FA, and n-6 and n-3 polyunsaturated FA, being n-3 higher in ripe olives. The ripeness stage can be distinguished by minor FA and minor TAG using MS.

Practical applications: Considering the high proportion of unsaturated and essential FA that make up olive seeds/olive seed oil, and knowing how these proportions shift according to olive ripeness, will allow different industries to explore several potential applications of these promising agro-industrial by-products. Besides, profiling the FA and TAG composition of olive seed oil by MS-based lipidomic approaches reveals that both the highest and the lowest abundant lipid molecules within these classes might be used as potential biochemical markers to discriminate these oils based on fruit ripeness stage.

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