A study at Universitat Rovirai Virgili has found that a special type of yeast speeds up the wine-making process and improves the wine's sensory properties. There is growing interest in carbonated macerated wines. These young red wines have rich floral and fresh fruit aromas and are best enjoyed within their first year. The most famous of these is Beaujolais Nouveau from France. However, similar traditions exist in La Rioja and Catalonia, especially in the Montesan and Barbera Conca regions.
URV's research found that the quality of these wines could be improved by using an unconventional yeast that significantly improves the wine's sensory properties and speeds up the malolactic fermentation process. This effect has also been found in orange and rosé wines.
carbonic maceration process
Carbonic maceration is a winemaking technique that consists of three stages. In the first stage, the whole grapes are put into a vat filled with carbon dioxide to create an oxygen-free environment, allowing alcoholic fermentation to occur inside the grapes. Many aromas are released during the fermentation process, and the resulting wine has fruity aromas of bananas and red fruits. A few days later, in the second stage, the soaked grains are pressed to complete alcoholic fermentation. In the third and final stage, the lactic acid bacteria in the wine induce malolactic fermentation.
A research team in the Department of Biochemistry and Biotechnology at Oregon State University has studied for the first time the effects of the yeast Torulaspora delbrueckii on carbonated macerated wines, rosé wines and orange wines. "Previous studies have mainly focused on traditional white and red wines, but we also studied other less common brewing methods. In addition, we not only studied alcoholic fermentation, but also the entire process from start to finish," explains Candela Ruizde Villa, lead researcher on the project.
During the study, they inoculated yeast strains and observed their impact on sensory characteristics and the malolactic fermentation process. Malolactic fermentation occurs after alcoholic fermentation and reduces acidity and adds complexity, smoothness and stability.
The influence of Brubaker's yeast
After the first stage of inoculation with Torulaspora delbrueckii, the wines produced were impressive: Candela Ruiz de Villa adds: "The carbonated maceration wines inoculated with this yeast are much more intensely colored than those inoculated with spontaneous yeasts, because anthocyanins - the compounds that give red wines their color - are protected." The researchers also observed an increase in aromas from some aroma families, such as banana, which are the dominant aromas in these wines.
Improvements in wine sensory properties were not the only findings. The team also found that the yeast also reduces the overall time of the brewing process.
The results of this study are important because they show that the addition of this yeast during carbonic maceration can be a new way to improve the quality of wine, enrich its aromatic profile and improve its sensory properties. Nicolas Rozès, a participant in the study, explains: "This maceration process allows the production of high-quality wines and offers wine producers a potential tool to differentiate their products in a highly competitive market. The results also prove applicable to rosé and sparkling wines."
The research was carried out in semi-industrial trials in 10-litre water tanks, followed the following year in 1000-litre tanks at the URV's experimental farm Masdels Frares. The results are identical to those obtained in the laboratory. "This yeast is actually already on the market, but now the producers have information they did not have before and they can apply it immediately," concludes Cristina Reguant, a researcher involved in the project.
Compiled source: ScitechDaily