Sourvisiae® Ale Yeast (Lallemand)

Sourvisiae® Ale Yeast (Lallemand)

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Sourvisiae® is a bioengineered ale yeast strain (Saccharomyces cerevisiae) capable of producing lactic acid during fermentation to provide brewers with an easy, reproducible, and mono-culture product for sour-style beer production.

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, the main compound that gives sour beers their flavor. Sourvisiae® allows the brewer to ferment and sour the beer in one simple step, reducing cross-contamination risks, lowering costs, cutting total process time, and allowing brewers to obtain a consistent product. 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 flavor compounds associated with Brettanomyces, Lachancea, or Lactic Acid Bacteria, providing a cleaner and more reproducible souring process, with much shorter fermentation times.

Microbiological Properties
Classified as a bioengineered Saccharomyces cerevisiae, a top-fermenting yeast. Finished product is released to the market only after passing a rigorous series of tests. *According to the ASBC and EBC methods of analysis.

Typical Analysis of Sourvisiae® Yeast:

  • Percent solids 93% – 96%
  • Living Yeast Cells ≥  5 x 10 9 per gram of dry yeast
  • Wild Yeast < 1 per 10 6 yeast cells
  • Bacteria < 1 per 10 6 yeast cells

Brewing Properties
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.

Flavor and Aroma
Tangy, sour, slightly fruity



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I like cheating.
James Rea on Jan 23, 2023
I like cheating.
James Rea on Jan 23, 2023

5.0 / 5.0
2 Reviews
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Rated 5 out of 5
Wow this yeast is awesome. I smiled when I took my first sip of the sour I made using this yeast.
January 19, 2023
1 month ago
Rated 5 out of 5
Amazing, no more kettle sours for me
I’m a professional brewer in Torrance, California. This new yeast strain is an amazing feat of bio engineering. I hate to share the secret, but another brewery told me about it and so I’ve been sharing how well it works. I’m on my third sour, already. ferments quickly, and cleanly sours quickly, is not affected by bittering hops in the kettle. Clears up great when cold crashed. The only downside is you can’t reuse it but it’s such a timesaver. It’s worth buying a new pack for each batch I do a seven barrel batch with one 500 g pack.
October 27, 2022