In vitro tissue culture as a tool for Croatian grapevine germplasm management

Drought poses a challenge to future viticulture, exacerbated by climate change, which increases the frequency and severity of water shortages.

In the La Mancha wine region, grapevines are regularly exposed to drought and heat waves, while the necessary water resources to mitigate these effects are becoming increasingly scarce.

Champagne or sparkling wines elaborated through the same traditional method, which consists in two major yeast-fermented steps, typically hold about 10 to 12 g/L of dissolved CO2 after the second fermentation in a closed bottle. Hundreds of molecules and macromolecules originating from grape and yeast cohabit with dissolved CO2; they are essential compounds contributing to many organoleptic characteristics (effervescence, foam, aroma, taste, colour…). Indeed, the second alcoholic fermentation and the maturation on lees (which may last from 12 months up to several years) both induce various quantitative and qualitative changes in the wine through the action of yeast, as listed hereafter: development of aromas during aging on lees, release of nitrogen compounds during autolysis and release of macromolecules (polysaccharides, lipids, nucleic acids) in wine.

Tropical fruit aromas in wines are thought to be important to wine consumers, although there is little research to confirm this statement. With so many wine styles available, it has become important to understand the qualities that are desirable to consumers and how to achieve those qualities. Thiols and esters are compounds that have been found to cause tropical fruit aromas in chardonnay (ref). Fermentation temperature gradients and skin contact were found to increase these compounds using micro scale fermentations. This work aimed to scale up these fermentations/operations to determine if the desired tropical fruit aromas could still be achieved and if there is a perceivable difference in tropical fruit aromas, liking, and emotional response in the wines at the consumer level.

Sulphur dioxide (SO2) is a well-established preservative in the wine industry. Its ability to act in different stages of the process as an antioxidant and an antiseptic as main characteristics makes it versatile. However, the need for its reduction or even its replacement has been increasing by the regulatory authorities as well as by the final consumer. To understand the impact of SO2 during ageing on volatile organic compounds (VOCs) and amino acids (AAs) profiles, two white wines (one varietal and one blend) were aged under the same conditions, in the presence of different doses of SO2. After fermentation (t=0), 0, 30, 60, 90 and 120 mg/L of SO2 were applied, wines were kept over lees for 3 months (t=3), then were bottled after 3 (t=6) and 9 (t=12) months.