Impact of Clonal Variability on Phenolics and Radical Scavenging Activity of Grapes and Wines: A Study on the Recently Developed Merlot and Cabernet Franc Clones (Vitis vinifera L.).

Milica Pantelić,Sonja Jović,Dragana Dabić Zagorac,Maja Natić,Jelena Popović Djordjević,Dragan Vujović,Uroš Gašić,François Blachier

doi:10.1371/journal.pone.0163823

Abstract

In this study, grapes and corresponding wines of Merlot /No 022, 025 and 029/ and Cabernet Franc /No 02, 010 and 012/ clones (recently developed) were evaluated regarding the total phenolic content, total anthocyanin content, and radical scavenging activity, aiming to better understand their quality and market potential. The nineteen individual polyphenols were quantified in studied grape samples using UHPLC coupled to a triple-quadrupole mass spectrometer. The mother grapes and wines were used as the relevant standards. In the grape, studied characteristics were monitored at three stages of berry development: green berry, véraison and mature berry. The mature grape of clones presented high values of total phenolics (3.81–10.89 g gallic acid equivalent kg-1 frozen weight), anthocyanin content (359.00–1668.18 mg malvidin-3-O-glucoside kg-1 frozen weight) and the radical scavenging activity (41.37–80.48 mmol trolox equivalent kg-1 frozen weight) depending on the clone. Grapes and wines of Merlot No 025 and Cabernet Franc No 010 stood out with the highest values of all three parameters. Generally, the high correlation was observed between TPC and RSA values for green berries and mature grapes, as well as for wine samples. The most abundant phenolics in both Merlot and Cabernet Franc grapes were gallic acid, p-hydroxybenzoic acid, ferulic acid, catechin, epicatechin, gallocatechin gallate, catechin gallate, and rutin. Catechin, epicatechin, epigallocatechin, and catechin gallate, typical for the ripe grape of Merlot and Cabernet Franc clones, showed significant correlation with RSA values. Concentrations of individual polyphenols varied depending on the sample being studied and berry development stages. Merlot No 025 and Cabernet Franc No 010 grapes showed particularly interesting attributes for the production of high quality wines.

Highlights

Grapevine (Vitis vinifera L.) is considered as the most important fruit crop in the world
Regarding the chemical composition of both Merlot and Cabernet Franc mature grapes our study revealed that the most abundant phenolics were gallic acid, phydroxybenzoic acid, ferulic acid, epigallocatehin, catechin, epicatechin, gallocatechin gallate, catechin gallate, and rutin
The first report on the phenolic profile of grape of Merlot and Cabernet Franc clones developed in Serbia, revealed significant differences between the grapes of standards and corresponding clones in respect to content of total polyphenols, anthocyanins, and radical scavenging activity

Summary

Introduction

Grapevine (Vitis vinifera L.) is considered as the most important fruit crop in the world. The grapes represent a significant component of the human diet and wine industry because of their richness in phenolics These compounds are secondary metabolites responsible for distinct functions in plants regarding the protection against biotic and abiotic environmental stress [2]. Among them anthocyanins isolated from the red grape berries (Vitis vinifera L.) have the simplest chemical structure of all the anthocyanins found in higher plants [4]. Their content in grapes is associated with some genetic factors (cultivar, clone), environmental and viticulture practices (light exposure, temperature, irrigation and nitrogen availability) [5]. The interest in wine phenolics is still increasing because of their antioxidant and free radical-scavenging properties, supported by the positive effects on cardiovascular diseases, cancer, diabetes, and others [8]

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