New yeasts to improve wine acidity

Climate change, particularly global warming, is having profound effects on various industries worldwide. The wine industry, too, is experiencing shifts. The alteration in acidity levels of wines, a critical aspect that determines their taste, texture, and longevity, is a rising concern for winemakers. Recent research from the University of California in Davis illuminates the genetic factors that might provide a solution.

Exploring the Saccharomyces cerevisiae Yeast

Saccharomyces cerevisiae, an essential yeast in the alcoholic fermentation process, is pivotal in wine-making. The study, published in the renowned journal "Nature," adopted a quantitative genetic approach to pinpoint genes within this yeast species that influence its acidifying properties.

It was observed that the metabolism of malic acid—a widespread organic molecule found in various fruits, including grapes—is influenced by the genetic activity of this yeast. Specific identified genes exhibited allelic variations that could lead to increased production or consumption of malic acid. This, in turn, directly impacts the final pH of the wine. Even a difference of 0.5 pH units can greatly alter a wine's organoleptic characteristics, affecting everything from its flavor to its conservation capability.

To grasp the genuine impact of these yeast strains on wine, comprehensive studies were conducted on various grape musts. These evaluations included routine phenotypic characterization, fermentation kinetics, basic enological analyses, and advanced techniques like targeted NMR metabolomics and untargeted LC-MS. The insights gathered presented a detailed account of the behavior and attributes of this yeast strain group.

The Vital Role of Acidity in Wine

Acidity is a cornerstone of wine's essence. It influences its taste, texture, and stability. A balanced acidity renders wine refreshing and long-lasting. While tartaric acid, followed by malic acid, are primarily responsible for wine's acidity, it's essential to note that tartaric acid breaks down over time, whereas malic acid remains stable throughout the wine's shelf life.

Global Warming's Impact on Wine's Acid Levels

The escalating average global temperatures due to global warming are tampering with the carbon cycle. This interference is leading to a noticeable reduction in wine's acidity levels. Malic acid, being a byproduct of carbon dioxide metabolism, gets affected when plants produce less carbon dioxide due to increased temperatures, thereby diminishing the malic acid content in grapes.

Traditional Techniques for Acidity Control

Winemakers have traditionally used methods such as malic acid addition or malolactic fermentation to manage wine acidity. While malic acid addition is an efficient method, it can modify the wine's flavor. Malolactic fermentation, on the other hand, is a natural process that transforms malic acid into the milder lactic acid, often aiding in balancing the wine.

Looking Ahead: The Potential of New Yeast Strains

These novel yeast strains might offer an alternative to conventional acidity control techniques. However, more research is required to gauge their efficiency and safety. Scientists are in the process of developing yeast strains that can produce or consume malic acid in more controlled amounts, which could aid producers in crafting wines with more consistent and precise acidity levels.