Image by Fermentis.

With Fermentis recently launching SafSour™ LB 1, their second dried bacteria into the market globally, we had a chat with Olivier Caille, Technical Manager for Fermentis, for a deep dive into this strain world and the new possibilities it brings to brewers.

Firstly, what drove the research and planning to bring SafSour™ LB 1 into the Fermentis range?

Olivier: Fermentis was searching for a way to achieve an equilibrium between the lactic and acetic acid notes produced by Lactic Acid Bacteria (LAB). A heterofermentative lactic acid bacteria could achieve this goal and a Levilactobacillus brevis was selected from among the Lesaffre collection specifically for that purpose.

What factors led Fermentis to be researching this equilibrium of acid production in LAB?

Olivier: Previously, Fermentis had launched Lactiplantibacillus plantarum SafSour™ LP 652, a homofermentative Lactic Acid Bacteria (LAB). This bacterium primarily converts glucose into lactic acid. To complement the SafSour™ range, Fermentis has specifically selected Levilactobacillus brevis, a heterofermentative lactic acid bacterium which converts glucose not only into lactic acid, but also has pathways to produce ethanol and acetic acid.

By introducing SafSour™ LB 1, we empower brewers to choose the acidity perception they want to develop in their sour beers, allowing them to achieve more flavour through the presence of both the lactic, and acetic acids at subsequent yeast fermentation stages.

Given the volume of breweries adopting kettle souring techniques to expand the diversity of their range, the Fermentis team have seized a great opportunity to support brewers’ creativity by introducing this new bacterium. A common perception of kettle soured beers produced with homofermentative LAB is the lack of acidic complexity developed. With only Lactic Acid contributing to tartness on the palate, the flavour profile can be hard to differentiate from beer to beer. The launch of SafSour™ LB 1 gives brewers’ the tools to have greater influence on this acidic character, creating avenues for their beers to stand out in the market.

Selecting the right bacteria to meet brewers’ evolving needs was no small accomplishment, with the Lesaffre collection boasting in excess of 10,000 unique yeast and bacteria. Which poses the question, what drove this particular heterofermentative strain to stand out and be selected amongst others analyzed?

Olivier: The advantages seen from testing with SafSour™ LB 1 stretched further than introducing acetic acid for improved complexity in kettle-soured beers. As with all styles, it is the balance of these organoleptic components that is essential. SafSour™ LB 1 promotes a desirable balance between the lactic and acetic notes, that enhances palate weight rather than confusing it. Further to that point, its equilibrium can be influenced by controlling the oxygen quantity into the wort prior to or during lactic fermentation. The more oxygen content in the wort, the more acetic acid production is enhanced.

Another option to homofermentative LAB, is that Levilactobacillus brevis SafSour™ LB 1 reveals a neutral aromatic profile, respecting the aromatic signature of the yeast used in the main alcoholic fermentation.

The collective benefits outlined amount to providing the brewer with more control mechanisms to refine their sour beers. With the improved acidic complexity being reason enough to warrant interest in trialing this new bacterium, the capacity to increase the aromatic profile of the primary fermentation yeast is an equally strong point of difference for the brewer.

Many brewers utilizing homofermentative LAB have a flexible approach to strain selection for the subsequent yeast fermentation, essentially due to the limited impact similar yeast strains can have on the organoleptic attributes. An example would be the selection of a var. diastaticus yeast that is positive for phenolic off flavour (POF+) such as SafAle™ BE 134, to create a dry sour with very low residual sugar. In such a combination, the final beer will display very little, if any, noticeable phenolic characteristics. It leads to a curiosity to understand the mechanisms that enable SafSour™ LB 1 to respect the subsequent yeast flavour expression where homofermentative LAB may not.

Olivier: Metabolically, Lactiplantibacillus plantarum SafSour™ LP652 consumes ferulic and p-coumaric acids contained in the wort. These compounds are precursors required for the subsequent POF+ strain to produce specific phenols, thus preventing it from producing its associated spicy aromatic notes when absent. The selected yeast characteristics are further masked and/or transformed by the citrus, tropical and peach notes that SafSour™ LP 652 produces during the lactic fermentation phase. It is a matter of the combination.

In contrast, Levilactobacillus brevis SafSour™ LB 1 does not consume the ferulic and p-coumaric acids, thus allowing the phenolic pathways from POF+ strains to stay active. It is also more aromatically neutral during the lactic fermentation, allowing the organoleptic profile of the subsequent yeast strain to express itself in the final beer.

With 15 Active Dried Yeast strains in the Fermentis SafYeast™ range dedicated to beer, the creative pathways for producing kettle-soured beers unfold quickly when pairing with SafSour™ LB 1.

Is there any further advice you can offer brewers looking to innovate, explore and create with either of the Fermentis SafSour™ strains?

Olivier: The SafSour™ range empowers brewers with a simple technique to produce sour beer through the kettle-souring process. Each strain will deliver consistency of flavour, and predictability in process for brewers.

Lactiplantibacillus plantarum SafSour™ LP 652 is suited to fruit driven sour beer styles, with accentuated citrus and stone fruit organoleptic influence, carried by a clean and linear Lactic acidity.

Levilactobacillus brevis SafSour™ LB 1 is recommended to produce any balanced kettle sour beer styles that demand complexity and finesse, such as a Gose or Berliner Weisse.

With the pace of exploration and creativity in brewing showing no signs of slowing, would it be safe to assume that there are more bacteria in planning to join the SafSour™ range in the near future?

Olivier: Bacteria constitute a very large and diverse source of microorganisms that can play an important role in beer diversification. It is an exciting area of exploration and innovation. Fermentis will certainly be a leading innovator in this category.

The opportunities to discover new tastes and pleasures are undoubtedly at all our fingertips with the introduction of SafSour™ LB 1. For further information on kettle souring techniques in general, visit our technical article or reach out to your local distributor and let SafSour™ LB 1 assist your creative endeavours.