Better, Faster, Foggier: Foggy London Improvements

When it comes to our goals of continuously improving the quality of our products and services, nothing is more valuable than customer feedback. This past summer, we noticed that some of our customers were unhappy with the performance of one of our most popular products, Foggy London Ale. Of course this didn’t sit well with us, so we set out to understand the problem and create an improvement.

From July until October of 2021 we dug deep into this problem. With our customers' help and insight, we were able to narrow our focus and we think we have made some significant improvements to the performance of this yeast.

What did we do? We did what we do best: listen to a problem and scientifically test possible solutions. We did research to compare Foggy London Ale to some competitor products to understand the problem, and tested some process tweaks to improve its performance. We learned a heck of a lot about this yeast along the way.

Are the strains different?

An easy answer would be "they're different strains". However, a wide range of evidence including genetic profiling, colony morphology (unique for this strain type), and microscope morphology (also fairly unique for this strain type) support Foggy London Ale and competitor strain(s) with similar names being very similar genetically. You may know these as “Juice”, “London 3”, “London Fog”, etc.

Characteristic “chain-forming” morphology of this yeast strain.

Results from Customer Feedback

We reached out to affected breweries and collected a lot of data to understand the problem. The correlation we found for poor Foggy performance was a high rate of calcium chloride in the wort. It was a surprise to us to hear how much calcium chloride was being used in some breweries - up to 0.25g/L, which would equate to 250 g in a 10 hectolitre commercial batch, or 5g in a 20L homebrew batch.

We knew we couldn't necessarily fix this or tell people to use less since calcium chloride is commonly used in large quantities to "soften" the profile of hazy IPAs. One brewer even described it to us as a “cheat code” for softer, juicier beers. This is because a higher ratio of chloride to sulfates in the brewing water is thought to reduce the hop bitterness, and calcium chloride addition is the most common way for brewers to pump up the chloride content of their wort. So we investigated to see if we could reproduce the issue in-house.

Do Calcium and Magnesium Levels Impact Performance?

We had a theory that the huge amounts of calcium chloride might throw the ratio between calcium and magnesium out of whack. Yeast cells benefit from both cations. Calcium is helpful for flocculation, while magnesium is helpful for growth and ethanol tolerance. Too much calcium could make it harder for the cells to take up magnesium, which might result in slower or stalled ferments.

We performed lab scale fermentations (400 mL) with pale ale wort containing no calcium chloride (0 g/L CaCl2), low calcium chloride (0.06 g/L CaCl2), medium calcium chloride (0.125 g/L CaCl2), high calcium chloride (0.25 g/L CaCl2) and high calcium with magnesium supplementation (0.25 g/L CaCl2 + 0.10 g/L MgSO4).

The wort was pitched at a rate of 12 million cells/ml (OG of the wort was 1.0530, approximately 13 degrees Plato) and incubated at 25ºC. Gravity readings were taken daily over a period of 7 days. Cells were taken directly from yeast pouches - no pre-growth.

In this experiment, we saw that medium-to-high amounts of calcium chloride slowed down Foggy's fermentation. Fermentation is faster at a low calcium concentration (0.06 g/L) which appeared to be the optimal calcium concentration for Foggy. Also, even though high amounts of calcium slowed down fermentation, supplementing the wort with magnesium at this high calcium concentration speeds up the fermentation. This supported our hypothesis that Foggy in its original state might be sensitive to the calcium: magnesium ratio.

We also included a competitor product in this experiment. It fermented faster than Foggy at medium and high calcium concentrations.

Since the competitor product responded quite differently to calcium and magnesium than Foggy, we thought it would be good to look at the propagation medium itself, namely the main ingredient: water.

Water is always top of mind for us here in Guelph, since our water is... unique, to say the least. It's very hard with high amounts of both calcium and magnesium already present.

Does propagation water source have any effect on the performance of Foggy?

We did some lab-scale fermentations with Foggy and a competitor strain which had been propagated in yeast media made with RO water or Guelph tap water. We wanted to find out if the high amount of calcium and magnesium present in tap water had an effect on Foggy which affected its fermentation performance downstream. For comparison, we included the competitor strain in these experiments to determine if the competitor strain was indeed a better strain than Foggy or if our propagation method negatively impacted Foggy.

For the fermentation, we pitched both strains at a rate of 12 million cells per mL in pale ale wort (OG=1.053) supplemented with no calcium chloride (0 g/L) or a high amount of calcium chloride (0.25 g/L).

The source of water used to prepare media for propagation has no effect on subsequent fermentation by Foggy and the competitor product. The graphs above show that the fermentation rate is pretty much similar when the strains are propagated in yeast media made with RO water or yeast media made with tap (Guelph) water. If anything, the tap water had a slight advantage over RO.

This data told us that the water wasn't the culprit. It must be some other ingredient. The ingredients used by each yeast lab to grow their yeast are slightly different. However the basic approach is fairly similar: a malt source, an additional nutrient source (yeast extract usually), hops, and some minerals for nutrient and pH buffering.

We were already tinkering with the yeast extract since our regular supplier was subject to frequent supply chain shortages (the story of 2021). Beyond water, yeast extract is also a major source of ions for yeast propagation, including both calcium and magnesium, and since we saw an impact of ion concentration on the performance of Foggy in our “original” propagation medium, we thought it would be a good idea to experiment with different yeast extract.

Different Yeast Extract

We grew Foggy in yeast media made with either the old yeast extract or the new one, and did lab-scale fermentations like before.

Eureka! When we swapped out the old yeast extract for a new product, magic happened: Foggy's performance dramatically improved. This improvement was consistent in a scale-up trial of Foggy grown in media prepared on our full-scale system, with the full-scale production batch grown with the new yeast extract and pitched into wort fermenting from 1.043 down to 1.028 in 24 hours, and 1.010 in 48 hours.

Finally, we obtained a fresh pitch of the competitor strain and compared Foggy grown on our main system to the competitor. Now, Foggy propagated with the new media formulation outperforms the competitor strain in most conditions including high calcium!

So while we still think it’s a good idea to watch the calcium to magnesium ratio, we are confident we have made Foggy London Ale ferments better and easier for brewers.


At Escarpment Labs we always take customer feedback seriously. We love hearing success stories, but learning about disappointments really helps us focus and continuously improve our products and services.

Thanks to feedback from our customers, as of mid-October 2021, all Foggy is being propagated with the new yeast extract (batch 21474 and onward). We are confident this change will improve Foggy London Ale performance for everyone. And if it doesn't - we want to hear from you and are committed to continuously improving our products based on your feedback.

Here is some feedback from one brewer who had problems in late 2020 and tried a recent batch of Foggy:

🌕 We are on the 4th generation of usage, we've fermented 6 beers with it so far. The short answer is the performance has been excellent.

Trials are ongoing comparing the sensory traits of Foggy London Ale and competitor strains. The focus of this post is on fermentation performance but we will report on sensory performance in 2022.

Credit where credit is due: all experiments presented were performed by Eugene Fletcher. Shelby Stein provided critical support for testing the changes in new malt lots. Suggestion to investigate calcium chloride additions was from Luisa Muhleisen. We’ve got a smart team of yeast nerds over here!

Additional note: The lab-scale tests are performed with different batches of wort produced on a homebrew system, so sometimes there is experiment-to-experiment variation in fermentability.

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