Moderating impacts of water addition in must by the use of Accentuated Cut Edges (ACE) vinification for <i>Vitis vinifera</i> cv. Shiraz winemaking

Abstract

In a warming climate, high-quality wine production is challenging due to grapes having higher sugar concentration, with wines being produced with higher alcohol levels, which can negatively impact final wine quality. Australian regulations now permit water treatment of pre-fermentation musts, which can ameliorate these effects, but final wines often lack colour and flavour. Accentuated Cut Edges (ACE) can overcome these drawbacks. ACE mechanically breaks grape skins into small fragments and accelerates phenolic extraction during wine fermentation, yet we do not know to what extent by reference to different applied levels of ACE. Expanding on previous studies, we implement ACE at three grape skin fragmentation levels: 10-second ACE treatment (low), 20-second ACE treatment (moderate (mod)) and 40-second ACE treatment (high), into pre-fermentation 15.5 °Bé musts for Vitis vinifera cv. Shiraz, which is then diluted with water to 13.5 °Bé. For chemical compounds, reduced total phenolics (a.u.) in diluted to 13.5 °Bé (no ACE) treatment wine (53.00 a.u.) can be addressed by diluted to 13.5 °Bé high ACE treatment, restoring levels similar to 15.5 °Bé (non-diluted no ACE) treatment wine (54.33 a.u.). Total tannins (%) are restored to a similar level as 15.5 °Bé (non-diluted no ACE) treatment wine (1.19 %) by diluted to 13.5 °Bé high ACE treatment (1.20 %). Sensory analysis for naïve wine consumers shows that diluted to 13.5 °Bé moderate ACE treatment produces wine with the greatest preference for colour intensity and increased preference for odour intensity and dark fruit taste. Further, 13.5 °Bé high ACE treatment produces a wine with the greatest preference for hotness and vegetal smell and an increased preference for dark fruit taste. Both diluted to 13.5 °Bé high ACE and diluted to 13.5 °Bé mod ACE treatment wines demonstrate a statistically significant increase in purchase likelihood when compared to 15.5 °Bé (non-diluted no ACE) and diluted to 13.5 °Bé (no ACE) treatment wines. If and when water treatment of pre-fermentative musts winemaking approaches become more widely accepted globally, it is important that all winemakers are provided with additional mitigation strategies such as ACE, which can further address any consequential impacts on final wine quality outcomes.