The Infestation of Olive Fruits by Bactrocera oleae (Rossi) Modifies the Expression of Key Genes in the Biosynthesis of Volatile and Phenolic Compounds and Alters the Composition of Virgin Olive Oil.

Andrés Notario,Pilar Luaces,Rosario Sánchez,Carlos Sanz,Ana G Pérez

doi:10.3390/molecules27051650

Andrés Notario, Pilar Luaces + Show 3 more

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https://doi.org/10.3390/molecules27051650

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Abstract

Bactrocera oleae, the olive fruit fly, is one of the most important pests affecting the olive fruit, causing serious quantitative and qualitative damage to olive oil production. In this study, the changes induced by B. oleae infestation in the biosynthesis of volatile and phenolic compounds in olive (cvs. Picual, Manzanilla, and Hojiblanca) have been analyzed. Despite cultivar differences, the oils obtained from infested fruits showed a significant increase in the content of certain volatile compounds such as (E)-hex-2-enal, ethanol, ethyl acetate, and β-ocimene and a drastic decrease of the phenolic contents. The impact of those changes on the inferred quality of the oils has been studied. In parallel, the changes induced by the attack of the olive fly on the expression of some key genes in the biosynthesis of volatile and phenolic compounds, such as lipoxygenase, β-glucosidase, and polyphenol oxidase, have been analyzed. The strong induction of a new olive polyphenol oxidase gene (OePPO2) explains the reduction of phenolic content in the oils obtained from infested fruits and suggest the existence of a PPO-mediated oxidative defense system in olives.

Highlights

Academic Editor: Luca FortiVirgin olive oil (VOO) has an exceptional aroma and flavor that distinguishes it from other vegetable oils
We found that BO infestation caused very similar effects on the aroma and flavor properties of VOOs produced from Manzanilla, Picual, and Hojiblanca olive fruits
The oils obtained from infested olive fruits showed significant increases in the content of the main C6 volatile compounds formed through the LOX

Summary

Introduction

Virgin olive oil (VOO) has an exceptional aroma and flavor that distinguishes it from other vegetable oils The assessment of these two properties by means of a specific sensory analysis is an essential requirement for the commercial classification of virgin olive oils [1]. For this purpose, expert tasters evaluate the green and fruity aroma notes, typical of freshly extracted VOO, and the intensity of the bitter and pungent taste notes of the oils. Volatile and phenolic compounds are responsible for these aroma and taste notes [2,3] Both types of compounds are produced during the industrial oil extraction process as a consequence of the destruction of the cellular integrity of the olive fruit that triggers a number of biochemical reactions. It is important to point out that phenolic compounds determine the flavor of the VOO, since due to their antioxidant activity they contribute to its well-known health benefits and improve the oxidative stability of the oils by reducing lipid peroxidation [8,9]

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