SEM characterization of olive (Olea europaea L.) fruit epicuticular waxes and epicarp

• All olive cvs. shown only epicuticular waxes arranged in crystalloid structures.
• Ultrastructure of epicuticular waxes plays an important role during fermentation.
• Shape and thickness of epicarp play an important role in table olive processings.
• Epicarp thickness decreases during ripening of fruits.
• SEM individualized features of epicarp and epicuticular waxes useful to processings.

Fruit cuticle micromorphology of several cultivars of Olea europaea L. was described with the aim to individualize features of the epicarp and epicuticular waxes useful to technological processings. All olive cvs. analyzed in this paper showed only epicuticular waxes arranged in crystalloid structures (granules, platelets, plates and rodlets). The epicarp aspects examined in this work were: the entire thickness of epicarp from surface to the base of epidermal cell, the height of the epidermal cell, the thickness of the cuticular flange that is wedged between epidermal cells and the thickness of the cuticular membrane, the continuous layer on the top of the epidermal cell. The cuticular membrane was the most important parameter, being the only barrier up the epidermal cells. Gentile di Chieti and Dritta cvs. had the thickest cuticular membrane (17.04 and 16.05 μm for green olives, respectively), Castiglionese, Carboncella and Kalamata cvs. had a medium cuticular membrane while the cuticular membrane of Intosso cv. was very thin (8.46 μm for green olives). The epicarp thickness decreased during ripening of fruits in all examined cultivars. Multivariate approaches were also used to identify similarities and differences between cultivars.

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