Sourvisiae is a bioengineered (GMO) strain of Saccharomyces cerevisiae capable of producing lactic acid in addition to alcohol during fermentation, for the simple and straightforward production of sour beers at home.

Sourvisiae contains a single genetic modification, a lactate dehydrogenase gene from a food microorganism, which enables the yeast to produce high levels of lactic acid when used as a pure culture, or lower levels when blended with another brewing yeast strain.

Sourvisiae allows the brewer to ferment and sour the beer in one simple step, reducing cross-contamination risks, lowering costs and cutting total process time. The brewing process is conducted without any modifications; Sourvisiae is pitched just like conventional yeast and ferments in a normal fermentation time. Sourvisiae does not produce other flavour compounds associated with Brettanomyces, Lachancea, or Lactic Acid Bacteria, providing a cleaner and more consistent and reproducible souring process.

Sourvisiae® is safe, non-hazardous and Generally Recognized as Safe (GRAS) by the US Food and Drug Administration.

In Lallemand’s standard conditions, wort at 20°c (68°F), Sourvisiae® yeast exhibits:

• Vigorous fermentation that can be completed in 5 days
• Medium to High Attenuation and Medium to High Flocculation
• Highly acidic and slightly fruity flavor and aroma
• The optimal temperature range for Sourvisiae® yeast when producing traditional styles is 15°C (59°F) to 22°C (72°F).

Fermentation rate, fermentation time and degree of attenuation are dependent on inoculation density, yeast handling, fermentation temperature and nutritional quality of the wort.

Attenuation may appear lower due to the formation of lactic acid. Production of lactic acid does not result in a loss of CO2. When sugar is consumed to produce lactic acid, there is no change in density. Therefore, the amount of residual sugar in the finished beer is lower than the final density would imply.

This yeast produces a very acidic beer, with final beer pHs in the range of 3.0 and lactic acid in the range of 8 – 15g/L. Vigorous fermentation can be completed within 5 days.

The resulting flavor and aroma profile of the beer is a slightly fruity acidic beer. Because of the resulting low pH and highly acidic conditions, we do not recommend re-pitching this yeast.