Looking for freshness in a warming world

Trends are shifting, and the wine industry is evolving in response. Not long ago, the intensity of wine was often used to define its quality. Today, winemakers and consumers place greater value on suppleness, balance, and especially freshness. Yet, as global temperatures rise, preserving freshness in wine is becoming increasingly difficult. In this context, wine yeasts are emerging as important tools to help meet the challenge.

Different yeasts, different wines

While transforming the sugars in the must into ethanol and carbon dioxide, yeasts produce a wide variety of compounds that influence the wine’s profile, including glycerol, organic acids, higher alcohols, esters, sulphur compounds, and polysaccharides, among others. The production of all these compounds varies according to the yeast strains. Some yeast strains can improve a wine’s sensory profile by reducing alcohol and/or increasing acidity.

To demonstrate this, a trial was conducted in September 2023 in the south of France. Syrah grapes were homogenised and placed into identical fermenters, with all winemaking conditions kept the same except for one variable: the yeast strain used for alcoholic fermentation.

Two ‘fresh’ modalities, ZYMAFLORE™ KLIMA and ZYMAFLORE™ KLIMA + ZYMAFLORE™ OMEGA^LT, were compared to a ‘classic’ control yeast, Saccharomyces cerevisiae. ZYMAFLORE™ KLIMA* (20 g/hL) was rehydrated with 20 g/hL SUPERSTART™ ROUGE. ZYMAFLORE™ OMEGA^LT (20 g/hL) and ZYMAFLORE™ KLIMA** (10/hL) were each rehydrated with 10 g/hL SUPERSTART™ ROUGE. All fermenters were inoculated for malolactic fermentation (MLF) with LACTOENOS™ BERRY Direct 24 hours after yeast inoculation. The analytical results are presented in Table 1.

Tabel 1: Analytical parameters of finished dry wines

ZYMAFLORE™ KLIMA for fresh and aromatic wines

In comparison, ZYMAFLORE™ KLIMA produced 0.3% less alcohol, with a decrease in pH of 0.2 units and an increase in titratable acidity (TA) of 1.7 g/L.  This is related to the metabolic ability of ZYMAFLORE™ KLIMA to produce malic acid from sugars during alcoholic fermentation, increasing post-MLF lactic acid. As a result, wine vinified with ZYMAFLORE™ KLIMA contains 0.5 g/L more lactic acid (corresponding to a difference of 0.75 g/L of malic acid before MLF). This wine also has a remarkably low volatile acidity, half that of the control.

ZYMAFLORE™ KLIMA and ZYMAFLORE™ OMEGA^LT : A Formidable Duo

Can we push the freshness even further? Absolutely! This becomes possible by combining the effects of ZYMAFLORE™ KLIMA and ZYMAFLORE™ OMEGA^LT. Used in co-inoculation or sequential inoculation with S. cerevisiae, ZYMAFLORE™ OMEGA^LT is a strain of Lachancea thermotolerans capable of transforming part of the sugars into L-lactic acid. Thus, the co-inoculation of the yeasts ZYMAFLORE™ KLIMA and ZYMAFLORE™ OMEGA^LT generated 0.8 g/L of additional lactic acid compared to the wine vinified with ZYMAFLORE™ KLIMA alone, resulting in even greater alcohol loss and acidification while preserving low VA production.

Impressive analytical differences, but what about the taste?

To answer this question, a large panel of 27 wine experts tasted the samples blind using the TASTEL WEB software. Unsurprisingly, the control wine had a muted aromatic intensity, with little fruit and freshness, but generous volume (Figure 1). On the other hand, the wine vinified with ZYMAFLORE™ KLIMA impressed with its bright fruitiness and freshness. The combination of ZYMAFLORE™ OMEGA^LT and ZYMAFLORE™ KLIMA was perceived as the most acidic but appreciated for its mouthfeel and pleasant, fruity expression.   

Figure 1: Average scores from 27 tasters

Want to make up your own mind? Don’t hesitate to test these fresh and fruity solutions on your grapes to give them exceptional freshness!