Harnessing the Unique Powers of Non-Saccharomyces Yeasts
Last updated: 6/2021
Applies to: Winemakers who are interested in using non-Saccharomyces yeasts. Learn how they can be of use in winemaking even without being able to finish fermentation. See end of article for a guide on selecting non-Saccharomyces yeasts from our portfolio.
WHAT ARE NON-SACC YEASTS?
The term non-Saccharomyces (or non-Sacc) is a colloquial term that is used to refer to the yeast associated with the pre- and early fermentation stages of winemaking that are not of the genus Saccharomyces. These yeast encompass approximately 20 genera and over 700 species. This diverse group of yeast has long been recognized for their contributions to wine aroma, flavor and mouthfeel; however, their behavior is largely unpredictable. Thus, active dried strains of non-Saccharomyces yeasts have been developed to harness their positive attributes.
Today, the non-Sacc yeasts available include strains of Torulaspora delbrueckii, Metschnikowia pulcherrima, Metschnikowia fructicola and Lachancea thermotolerans. Non-Sacc yeasts often work in different ways than traditional Saccharomyces strains. These organisms are either non-fermentative or mildly fermentative and do not have the ability to complete alcoholic fermentation.
Non-Sacc yeasts can enhance aromas and mouthfeel and modulate acid composition allowing you to drive a specific wine style. Non-Sacc yeasts can also act as antimicrobial and antioxidant agents. Their actions are different from traditional winemaking tools like SO2, however during the pre-fermentative stages these yeasts can be more effective than SO2.
NON-SACC SPECIES FOR WINEMAKING
Metschnikowia species can protect from microbial spoilage (bioprotectant)
Adaptation is the key to survival. Organisms with successful adaptation strategies are more likely to survive than others. LEVEL² INITIA™ and GAIA are different species of Metschnikowia that can inhibit indigenous microflora. This allows them to survive in the challenging juice/must environment. However, their adaptation and survival mechanisms differ. Indigenous yeast require oxygen. INITIA, is a specific strain of Metschnikowiapulcherrima that very quickly scavenges oxygen leaving the juice depleted. INITIA in part survives due to its ability to outcompete indigenous microflora for oxygen. GAIA, a specific strain of Metschnikowia fructicola suppresses indigenous organisms via a phenomenon called microbial crowding. By using INITIA in white or rosé juice, or GAIA in red must, these bioprotectants suppress volatile acidity-causing yeast and bacteria.
M. pulcherrima and Torulaspora delbrueckii enhance volume and aromatic complexity
LEVEL2 FLAVIA™ and LEVEL2 BIODIVA™ are strains of Metschnikowia pulcherrima and Torulaspora delbrueckii, respectively. These organisms have interesting enzymatic abilities that S. cerevisiae does not. Inoculated into the fermentation vessel, FLAVIA can release bound varietal compounds like thiols and terpenes whereas BIODIVA produces esters. This means that wines are more complex with enhanced tropical, citrus, fruity and spicy aromas. These specific strains of non-Sacc can also impact mouthfeel due to release of mannoproteins (FLAVIA) or polyols like arabinol (BIODIVA). BIODIVA and other Torulaspora delbrueckii strains can initiate fermentation, therefore, they should not be used as a bioprotectant.
Lachancea thermotolerans can modulate acid composition
LEVEL2 LAKTIA™ is a strain of Lachancea thermotolerans that can produce lactic acid and other minor metabolites from glucose. This production of lactic acid can have an impact on pH and titratable acidity. Depending on the level of lactic acid produced (2->9g/L) LAKTIA can be used to enhance complexity or give an interesting blending component for wines lacking freshness.
SELECTING NON-SACC YEAST FOR SUCCESS
While they require a bit of extra care, the non-Saccharomyces yeasts in our portfolio are powerful tools to enhance wine quality and allow the winemaker to achieve their desired wine style. Be sure to keep in mind the following when working with Non-Sacc yeasts:
- To ensure a complete alcoholic fermentation, a Saccharomyces strain should be added, and the YAN adjusted accordingly. This is because non-Sacc yeast have a very low tolerance to ethanol and CO2, therefore their activity and viability drops once alcohol reaches approximately 5% v/v.
- Always be sure to consult strain-specific instructions when using a non-Saccharomyces yeast for two reasons:
- Non-Sacc yeasts need to be rehydrated differently from Saccharomyces yeasts.
- The timing of your secondary Saccharomyces inoculation will depend on the Non-Saccharomyces strain you have selected.