Questions (italicized) by a patron of the GotMead forum, and Answers by our Head of R&D, Chris Herr

A Q&A On Making Sour Meads

I am curious about making a sour mead. I jumped in this weekend and pitched some Lactobacillus Brevis (WLP 672) into a very low gravity honey must (about 1.050) with the intention of adding this to a mead with the same starting gravity fermented with Safale US-05.

1. I assumed that the l Brevis batch needs to be sealed from oxygen from the minute I pitch the yeast? Is that in fact correct? I aerated the must. Was that in fact a mistake?

CH: First I'd like to state that our knowledge and protocol for creating sour meads is constantly evolving. 

Our current protocol is to pitch the lactobacillus with the yeast, Safale 05, using the SNA and degassing schedule we do for our normal meads. Doing this we've produced a brightly tart mead. We've slated further experiments trying to refine this, looking at pitch rate for the lacto and pitch timing (start of fermentation vs 1/2 sugar break). The major pitfall so far has been PH. Our last experiment stalled out at 6 Brix with a PH of 2.8. Our next experiments will include PH buffering at the start of fermentation.

To answer this first question, Lactobacillus is anaerobic and doesn't require oxygen, but there are plenty of things fermented with lacto using an open air process. Keeping it sealed would be prudent to preventing an infection of another bacteria or yeast. 

We've yet to have an issue after aerating the must, you should be fine. 

2. Will the l Brevis batch continue to become more sour even after all the sugars have been fermented?

CH: My understanding is lactobacillus only metabolizes sugar, so once that has run out it shouldn't get any more sour. We've found with some of our sours that as they age they mellow out, the sourness giving way to the honey.

3. I am assuming that the l Brevis will eat the fructose and glucose in the honey. Am I wrong?

CH: Yes. I've been told it prefers glucose, but it should eat both.

4. I normally feed my meads nutrients. Does the l Brevis have the same kind of need?

CH: I asked our yeast wrangler, Dr. Pfau, and was told lactobacillus has similar nutrient requirements to yeast.

5. How long can I expect that fermentation to run?

CH: Our regular fermentations run three to four weeks, our sours take at least a couple of weeks longer. Your SG is about half ours, so it should be quicker. I don't know how long an all lacto ferment would take.

6. Is my idea of blending the two batches a sensible one or would it have made more sense to pitch both the 05 and the l Brevis at the same time into the same fermenter? (My thought is to see if a better mix is 1:1 OR 2:1 OR 1:2 etc)

CH: We've used blending before to good effect, and it's a common practice for aged sour beers. If it gives you the results you're after it's a perfectly sensible choice. We pitch both together because it's a much easier process for us to scale. 

Let us know how it turns out. If you attempt our protocol we'd love to know how it worked for you. If you have any more questions don't hesitate to send them our way.

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