UNRAVELING THE CHEMICAL MECHANISM OF MND FORMATION IN RED WINE DURING BOTTLE AGING : IDENTIFICATION OF A NEW GLUCOSYLATED HYDROXYKETONE PRO-PRECURSOR

This study aimed to determine mineral composition in red wine obtained from cv. Teran (Vitis vinifera L.), autochtonous Croatian grape variety. Six different vinification treatments, including the control treatment (7-day standard maceration), were performed to study the effects of: 48-hour pre-fermentative mash cooling (8 °C) followed by prolonged post-fermentative maceration of 13 days (C15), 28 days (C30), and saignée technique (juice runoff) proceeded with prolonged post-fermentative maceration of 13 days (CS15); and effect of 48-hour heating (50 °C) followed by prolonged post-fermentative maceration of 13 days (H15) and 28 days (H30) on macro- and microelements in wine.

Smoke impacts on wines are becoming a worldwide problem; the size and severity of wildfires increasing due to influences from changing climates.¹ For over a century, wines have been known to have a unique issue of absorbing chemical compounds derived from wildfire smoke wherein the flavor of the subsequent wine becomes ashy, rubbery, campfire-like, and smoky.² The economic impacts of a smoke-impacted wine can last for years depending on the grape varietal, costing Oregon and Washington states in the United States over a billion dollars from the 2020 wildfires, as an example.³ While years of research have indicated elevated concentrations of smoke-related compounds, such as guaiacol and syringol, in wines after smoke events, unfortunately, replicating the sensory experience using smoke-associated phenols has not had much success.⁴

Nowadays, the rapid growth of vineyards with organic practices and the use of copper as the only fun-gicide against downy mildew raises again the question of the effect of copper on varietal thiols in wine, especially 3-sulfanylhexan-1-ol (3SH) and its acetate (3SHA). A few decades ago, several works indicated that the use of copper in the vineyard had a negative effect on the content of varietal thiols in Sauvignon blanc wines [1, 2]. However, these studies only considered the concentration of the reduced form (RSH) of varietal thiols, without quantifying the oxidised ones. For this purpose, we proposed to monitor both reduced and oxidised forms of varietal thiols in wine under copper stress during alcoholic fermentation to have a more complete picture of the biological and chemical mechanisms.

Biodynamic agriculture, founded in 1924 by Rudolph Steiner, is a form of organic agriculture. Through a holistic approach, biodynamic agriculture seeks to preserve the diversity of agriculture and the existing interactions between the mineral world and the different components of the organic world. Biodynamic grape production involves the use of composts, herbal teas and mineral preparations such as 500, 501 and CBMT.
Several scientific studies have provided evidence on the effects of biodynamic farming on the soil, the plant and the wine. Numerous empirical opinions of wine growers support the existence of differences brought by such a management.

Lugana wines are made from Turbiana grapes. In recent times, many white and rosé wines are bottled and stored in flint glass bottles because of commercial appeal. However, this practice could worsen the aroma profile of the wine, especially as regards the development of volatile sulfur compounds (VSCs). This study aims to investigate the consequences of exposure to light in flint bottles on VSCs profile of Lugana wines fermented with two different yeasts and with different post-fermentation residual nitrogen.