Struck flint aroma in Chardonnay wines: what causes it and how much is too much?

Champagne wines are produced via a two-step process: the first is an initial alcoholic fermentation of grape must that produces a still base wine, followed by a second fermentation in bottle – the prise de mousse – that produces the effervescence. This appellation produces non-vintage sparkling wines composed of still base wines assembled from different vintages, varieties, and regions. These base wines, or “reserve wines,” are typically conserved on their fine lies and used to compensate for quality variance between vintages (1). Continuously blending small amounts of these reserve wines into newer ones also facilitates preserving the producer’s “house style.”

Pilzwiderstandsfähige (PIWI) are disease resistant Vitis vinifera interspecific hybrid varieties that are receiving increasing attention for ability to ripen in cool climates and their resistance to grapevine fungal diseases. Wines produced from these varieties have not been characterized, especially regarding their macromolecular composition. This study characterised and quantified colloid-forming molecules (proteins, polysaccharides and phenolics) of red PIWI wines produced in the UK. METHODS: In 2019 6 wines were made from the PIWI varieties Rondo, Cabernet Jura, Cabernet Cortis, Cabernet Noir, Regent and Cabertin grown at the Plumpton Rock Lodge Vineyard in Sussex (UK) and harvested at similar level of maturity (TSS, pH and TA). All juice was chaptalized to the same potential alcohol of 12%. Small scale winemaking (1L) was performed in quadruplicate using Bodum® coffee plungers to manage maceration [1]. Residual sugar content, pH, and titratable acidity were monitored during fermentation. For finished wines, the protein and polysaccharide content was measured by HPLC-SEC [2], while the total phenolic content was assessed using the Folin-Ciocalteau method [3]. The protein profile of the wines was further investigated by SDS-PAGE [4]. RESULTS: Fermentations (n=24) were all carried out to completion within 8 days.

Currently, to consistently ensure the maintenance of a wine-style while benefiting from the utmost rigor made possible by the winemaking process, the composition of the wine blend is made using sensory control. This is performed after the wine is made with no real possibility of deterministic intervention.

Climate change and rising temperatures present a substantial challenge to viticulture, intensifying summer heat stress and accelerating berry ripening.

Forest fires in the vicinity of vineyards have significantly increased in the last decade and are a concern for grapegrowers and winemakers in many wine producing countries. The fires cause smoke drift throughout vineyards which cannot be avoided and may result in the production of wines described as ‘smoke tainted’. Such wines are characterized by undesirable sensory characters described as ‘smoky’, ‘burnt’, ‘ash’ aromas and flavours, and also may cause a lingering, unpleasant ashy aftertaste [1; 2].