Effect of the harvest season on phenolic composition and oenological parameters of grapes and wines cv. ‘Touriga Nacional’ (Vitis viniferaL.) produced under tropical semi-arid climate, in the state of Pernambuco, Brazil

Juliane Barreto De Oliveira,Ricardo Egipto,Jorge Manuel Ricardo-Da-Silva,Diana Lemos Faria,Olga Laureano,Giuliano Elias Pereira,Rogério De Castro,Daniel Fernandes Duarte

doi:10.1051/ctv/20183302145

Abstract

The northeastern region of São Francisco Valley is the third largest wine producer in Brazil, differentiated by the production of at least two harvests per year, generally in the first and second semesters, respectively. The productive cycle of the vine in the first semester is higher than in the second semester, mainly due to differences in temperature, with maximum and average temperatures of approximately 30 ºC and 26 ºC, respectively. Second semester is characterized by higher temperatures (summer season) and that promote a rapid maturation of the grapes. The objective of this work was to evaluate the phenolic composition, other oenological parameters and the sensorial profile of grapes and wines of cv. 'Touriga Nacional' (Vitis viniferaL.), characterizing grapes and wines from four harvest seasons, two of them referring to the first half of the year and two referring to the second half of the year, using a broad analytical approach. The experimental design consisted of three randomized blocks, with sixty plants marked in different lines and positions (twenty plants in each block at the beginning, middle and end of the vineyard). The results showed that there was a harvesting effect for some of the grape chemical compounds (monomeric anthocyanins, organic acids, condensed tannins and monomeric flavanols, for example) as well as in wines (calcium, monomeric anthocyanins, condensed tannins and monomeric flavanols). Regarding the sensorial profile of the wines, it was possible to observe that higher scores were attributed to floral aroma in wines from the first harvest (first half of the year). Fruity, spice and empyreumatic aromas were higher in wines from second harvest season (second half of the year). For other attributes, there was a tendency for higher variations between the period of study (2014 – 2017) than between the harvest seasons.

Highlights

Tropical viticulture is typical from regions where minimum temperatures are not low enough to induce the vine to dormancy
It is possible to verify high pH values in ‘Touriga Nacional’ grapes on both harvest seasons, a fact that may be related to the high potassium content found in soils in this region (Soares and Leão, 2009), which reflect the formation of acid salts at the expense of free acids
This study pointed out the effect of the harvest season on some chemical compounds of grapes from ‘Touriga Nacional’ cv. from a semi-arid region of northeastern Brazil

Summary

Introduction

Tropical viticulture is typical from regions where minimum temperatures are not low enough to induce the vine to dormancy. The vine grows continuously and with the use of appropriate technology is possible to obtain two or more harvests per year in the same vineyard. The main poles of tropical viticulture in Brazil are Submédio São Francisco Valley, northwest Paulista and north of Minas Gerais (mainly for table grapes). The term “Terroir” is diverse and involve several factors that influence the composition of the grapes and of the wines from a specific region. The environmental characteristics (climate and soil conditions) and cultural practices applied in the vineyards are important examples of these factors (Downey et al, 2006; Gutiérrez-Gamboa et al, 2017, GutiérrezGamboa and Moreno-Simunovic, 2018)

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Conclusion