Performing sequential harvests based on berry sugar accumulation (mg/berry) to obtain specific wine sensory profiles

Guillaume Antalick,John W Blackman,Alain Deloire,Katja Šuklje,Leigh M Schmidtke

doi:10.20870/oeno-one.2021.55.2.4527

Guillaume Antalick, John W Blackman + Show 3 more

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https://doi.org/10.20870/oeno-one.2021.55.2.4527

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Abstract

This study aimed to investigate the possible existence of reproducible aromatic red wine styles, focusing on fresh fruit aromas and mature fruit aromas (i.e., with dark, jammy fruit characteristics) and taking into account both vintage and vineyard.The study was performed on Australian Shiraz and Cabernet‑Sauvignon from three different meso-climate areas and two consecutive vintages. Sequential harvests were carried out based on the plateau of the physiological indicator berry sugar accumulation (mg/berry) in order to obtain fresh fruit and mature fruit wine sensory profiles. There was a predictable aromatic sequence during grape ripening at each of these two distinct maturity stages regardless of grape genotype (variety) and environment (vineyard and vintage). The post-plateau period of berry sugar accumulation was found to be crucial for the evolution of wine aromatic profiles. During this period, wine aromatic and phenolic maturity were uncoupled from technological maturity (i.e., berry sugar concentration). Dimethyl sulfide was found to be the most relevant wine aromatic marker for differentiating the fresh fruit and mature fruit stages irrespective of the variety. Specific cultivar markers with potential sensory contribution were also identified; for example, (Z)‐3‐hexenol, a possible contributor to the aromatic freshness of Shiraz wines from the fresh fruit stage. The evolution of terpenoids appeared to be separate from the dynamics of berry ripening post plateau of fruit sugar accumulation. On the other hand, ester composition was significantly altered during the same ripening period in Shiraz and Cabernet‑Sauvignon wines with a marked grape genotype effect. The results showed that yeast metabolism was also affected by berry ripening evolution from the plateau of berry sugar accumulation onwards.

Highlights

One of the most important and difficult tasks for a viticulturist or winemaker is predicting/assessing harvest dates that will ensure the production of wines with preferred styles
Differences were observed between vineyards and vintages in terms of the dates when the berry population reached the plateau of sugar accumulation; this reflects the variations in berry ripening dynamics and the asynchrony of berry development (Shahood et al, 2015) linked to climatic conditions, viticultural practices and varieties
Shahood et al (2020) recently proposed a model of berry ripening based on measurements carried out on thousands of individual berries, whereby the plateau of berry sugar accumulation was reached at 1M sugar (18 °Brix), and further sugar concentration increases were due to berry water loss only

Summary

Introduction

One of the most important and difficult tasks for a viticulturist or winemaker is predicting/assessing harvest dates that will ensure the production of wines with preferred styles. The decision to harvest grapes for wine production can be determined by measuring grape berry sugar concentration as total soluble solids and expressed as °Brix (technological maturity). While berry tasting is relevant, it is highly subjective as the perception of flavours depends on the taster’s personal ability, experience and training (Rabot et al, 2017). It would be useful for growers and winemakers to be able to objectively predict wine aromatic profile evolution during ripening by measuring simple physiological grape parameters, such as berry sugar accumulation which is dependent on vineyard growing conditions (soil × climate × cultural practices)

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