Potential application of indigenous Pichia kluyveri for enhanced wine aroma quality

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.

Occurrence of freezing temperatures in early spring when grapevine shoots are developing is termed late frost in viticulture. Young green tissues are very sensible to temperatures below zero and damages often lead to important yield and quality losses such as the case in Europe in 2017. An indirect method to avoid late frost damage in vineyards consist in delaying the budburst. Previous research reported similar effects by applying vegetal oil on dormant buds. Here, we tested the application of rapeseed vegetal oil during late winter to delay the budburst on two V.vinifera cultivars of interest in Austria, Grüner Veltliner (GV) and Zweigelt (ZW).

The aging potential of Burgundy chardonnay wines is considered as quality indicator. However, some of them exhibit higher oxidative sensitivity and premature oxidative aging symptoms, which are potentially induced by no-enzymatic oxidation such as Fenton-type reaction (Danilewicz, 2003). This chemical mechanism involves the action of transition metal, native phenolic compounds and oxygen which promote the generation of highly reactive oxygen species (ROS) such as hydroxyl radicals (OH) or 1-hydroxyethyl radicals (1-HER) from oxidation of ethanol. Such mechanism is involved in the radical oxidation occurring during bottle aging. According to Elias et al.,(2009a), the 1-HER is the most abundant radical in forced oxidation treated wines. Consequently, understanding its evolution kinetic in dry white wines is of great importance.

he final concentration of phenolic compounds in the wines is usually lower than what might be expected given the phenolic concentration measured in grapes

Within a research project for simulating the nitrogen turnover in vineyard soils and the nitrogen uptake by the grape vine, a previously developed plant growth model (Nendel and Kersebaum 2004) had to be evaluated. A dataset was obtained from a monitoring experiment at three vineyard sites with different soil types, conducted in the years 2003 and 2004.