Many years have passed by since Dom Perignon had invited his brothers to taste the stars, yet we continue to taste them.
The method Dom Perignon was using to make sparkling wine then is still valid today, and it’s called traditional method, also known as “Champenoise method”. It’s a method that requires a lot of labor and effort. All the steps for making still wine are done including alcoholic fermentation. This still wine is used as a “base” for the sparkling wine. Then comes the second alcoholic fermentation that creates the bubbles. This is made in the actual bottle in which the sparkling wine will be sold. After this process, the bottles are left to age at least nine to twelve months, in most cases for years. What gives the uniqueness of the traditional method sparkling wines is this process of fermentation in bottle and aging. Along with the bubbles, tertiary aromas are also formed as the wine is in contact with lees – the deposits of dead or residual yeast.
So much responsibility is under the shoulders of the yeasts during sparkling winemaking. First of all, they need to perform inside of the bottles and consume all the sugars to produce alcohol and bubbles, but they also change the organoleptic characteristics such as texture and aromas. Therefore, for sparkling winemaking, we need to choose a suitable yeast that will be successful in fermentation and enhance the aromas.
There are many different commercial yeasts available for winemakers to choose from. Saccharomyces cerevisiae is the most common yeast in enology. So common that it’s called “conventional yeast” for winemaking. However, there are more and more researchers and winemakers believing the conventional yeast brings “uniformity” to wines, causing producing wines with similar aromatic profiles. Therefore, a lot of studies are being done to discover “non-conventional” yeasts.
Non-Saccharomyces yeasts are a group of these non-conventional yeasts. For my thesis project in Universidad Politecnica de Madrid, I decided to work with two of these Non-Saccharomyces yeasts for sparkling winemaking. The idea was to use these non-conventional yeasts for the second fermentation in a bottle and see if there will be any difference in their chemical and organoleptic characteristics.
We used two base wines, white wine from Airen and red wine from Tempranillo, and three different yeasts to perform second fermentation in bottle – two non-Saccharomyces yeasts Schizosaccharomyces pombe and Saccharomycodes ludwigii, and Saccharomyces cerevisiae as control. After making all steps of the traditional method in laboratory conditions, we aged them on lees for five months.
After the aging process, we had organized a tasting with a panel of eleven experienced tasters to evaluate the samples and observe the differences in the defined parameters. We also conducted some chemical analyses to compare their analytical characteristics. The results were very positive.
First of all, we did have a difference in between the samples, especially for the attributes of color intensity, volatile compounds and acidity.
In the sparkling wines produced with different yeasts, different volatile compound profiles were detected. This means the wines had different aromas such as fruity, yeasty or buttery aromas. Although we found many organoleptic differences among the yeasts, the panel didn’t perceive differences in their total quality parameter. This shows a positive side of using non-conventional yeasts in traditional sparkling method – you can obtain a different aroma profile, without decreasing the overall quality.
We also found differences in the color parameter especially important in red and rosé sparkling wines. This was not surprising, as the yeasts can impact on the anthocyanin content of the wines. It was the case in our study. One of the yeasts we used, Schizosaccharomyces pombe, showed a significantly darker color due to high anthocyanin content and it was also preferred by the tasting panel.
Nowadays the quality and style of the sparkling wines are getting more influential in the competitive wine market. So, it’s more than needed to find the different ways to improve and differentiate this product. Using non-conventional yeasts is one of them. This is how we can keep updated with scientific knowledge, answer the demands of the market, and produce sparkling wine to satisfy the customers.
All images © 2016 by Wines of Nesli. All rights reserved.
Update November 2017: The paper we published about this study can be found in here.