The wine industry is currently facing a silent but constant challenge: climate change, which has altered the way wine is produced, as grapes exposed to higher temperatures ripen faster and concentrate more sugar than normal, resulting in high alcohol levels.
This phenomenon not only affects wine quality, but also causes commercial problems, since higher alcohol content means higher taxes for producers and a health issue that cannot be ignored. At the same time, other areas of the industry, such as pisco and bulk wines, face the opposite challenge, as they need to increase fermentation efficiency to achieve higher production levels.
For over a decade, Dr. Claudio Martínez, a researcher at the University of Santiago, Chile's Department of Food Science and Technology, has delved into this complex area. His initial work involved meticulously collecting and characterizing wild yeasts across diverse ecosystems in Chile and Latin America, seeking to unlock their natural diversity and fermentative potential. Now, the focus has shifted to the intricate process of crossbreeding these yeasts and, perhaps even more challenging, creating the necessary tools to identify their microscopic offspring.
"We learned how to cross two yeasts, how to identify their offspring, and how to work with large populations. We built up a base of knowledge that now allows us to approach this problem from a different angle. If we can get the yeast to do what we want it to do, that is, produce more or less alcohol, depending on what is required, then we will be solving the problem without altering the process or the quality of the wine," he explains.
The idea is simple: to develop new strains of Saccharomyces cerevisiae, the yeast species responsible for transforming sugar in must into alcohol, that are capable of producing different levels of alcohol, depending on the needs of the production process. To achieve this, wild strains must be crossed without using transgenic organisms, i.e., traditional genetic improvement, as has been used historically in plants and animals, but adapted to microorganisms.
"The alternative we came up with, which is classic in all types of organisms, is genetic improvement through crossbreeding, that is, crossbreeding and improving an organism in this way, which is the same as what is done with animals and plants and is actually the basis of the world's food supply. So, to put it simply, male and female yeast are crossed, and then natural selection takes place, or the most adapted are selected, so to speak, and they are crossed again with another stronger one," explains Usach academic Claudio Martínez.
Currently, the solutions available on the market to control the alcohol content of wine aim to correct the problem after fermentation. Some producers use expensive equipment to remove alcohol, which often alters other components of the wine. Others resort to diluting the must, a practice that affects quality and conflicts with international regulations.
A viable and sustainable solution
In this scenario, an alternative that acts at the beginning of the process, without artificially modifying the wine or intervening in later stages, appears to be a viable and sustainable solution. If successful, this line of research would improve the quality of Chilean wine, reduce costs associated with alcohol taxes, and eventually offer more affordable prices for consumers. In addition, it would lay the foundations for the development of a national yeast industry, a strategic input that is currently imported almost in its entirety.
“Hopefully this will also drive the development of new industries, such as yeast production, which I believe is strategic for the country. Having our own strains, developed with funding and support from the Chilean government, could become a real product that boosts the biotechnology industry, and the only way to do this is for projects like this to reach their destination.”
The project is expected to take four years to complete. In the first stage, the team will work on crossing different yeast strains to obtain new variants with different levels of alcohol production, which will be evaluated under conditions similar to those found in a winery. Next, the genetic material of the most promising strains will be analyzed to understand which genes are behind their behavior. Finally, these yeasts will be tested in pilot fermentations alongside collaborating vineyards, and the resulting wine will be evaluated by specialists.
"If, in a few years, I see these yeasts being used in Chile, generating employment, quality, and innovation, then I'll consider myself fulfilled as a researcher," Dr. Claudio Martínez concludes.