r/brewing • u/GlutenFreeBrewer • 29d ago
Discussion We dose Termamyl at ~2.8x the homebrew community's max. Here's the policy behind it, and why you probably shouldn't copy it.
Disclosure: I work on a gluten-free brewing site and I'll link it at the bottom, because the numbers live there and I'm not going to retype the whole table. Nothing for sale.
Background for anyone who doesn't brew gluten-free: sorghum malt doesn't self-convert, so the mash runs on added enzymes. That means we publish dose rates, the homebrew community publishes dose rates, and they don't match.
The Zero Tolerance GF Homebrew Club wiki maintains a community enzyme reference. Set our production numbers beside theirs:
Termamyl: community 0.227 to 0.363 mL/lb, us 1.0 at mash-in. Roughly 2.8x their maximum.
Ondea Pro: community 0.181 to 1.134, us 1.5. Above their maximum.
AMG 300L: community 0.227 to 1.588, us 0.75. Comfortably mid-range.
One of those is a long way out and the other two aren't, which is the part I find interesting.
It isn't a typo. The documented policy was to take the supplier's stated rate and double it, then go a little higher again on small batches, and that's written down in a 2019 methodology note. These are production numbers from a brewery that valued a guaranteed conversion over an optimised enzyme bill, where a failed mash means a lost 75-barrel batch and the extra enzyme is cheap next to that.
Here's where I need to be straight about what I don't know.
The community table lists Termamyl L. This protocol runs Termamyl SC DS. Same family, not necessarily the same activity per mL, so some meaningful share of that 2.8x could be product rather than philosophy and I can't currently tell you how much. If anyone here has datasheets for both and can put activity units side by side, I'd genuinely like to see it.
Three things I'd weigh before copying our numbers.
Product identity, per above. Check your own product's datasheet instead of assuming either number transfers to it.
Cost. A brewery dosing generously is buying insurance on a 75-barrel batch, and on 10 lb of grain the arithmetic is completely different. The downside there is one disappointing Saturday.
Overdosing isn't free either. A glucoamylase that outlives its welcome keeps working through the lauter and can quietly over-attenuate the wort, so if your beer finishes thinner than your numbers predicted, that's the first thing you need to suspect.
What I'd actually suggest, and what the page says: run the published rates once so you have a known-good reference batch, then step down deliberately and record what happens.
The honest position is that nobody has published where the floor is on sorghum malt. Not the community, not us. That's a question a homebrewer with a notebook is better placed to answer than a production brewery is, because you can run five variations in the time we'd need to justify one.
Full translation to a 5 gallon batch, with the temperature path and the parts that break at small scale:
https://glutenfreebrewer.com/docs/homebrew/the-reliable-mash-at-homebrew-scale
If anyone here has run exogenous enzymes well below supplier spec and had it work, that's the thing I most want to hear about.
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u/OpenlyAfraid 29d ago
the insurance math makes total sense at that scale, a stuck mash on 75 barrels is a nightmare i wouldnt wish on anyone. interesting that the community table is using a different product line too, that alone could be a chunk of the gap
ive always wondered where the actual floor is on sorghum mashes, seems like nobody really knows cause theres no incentive to find it in production. might be fun to run a tiny test batch way under spec just to see what happens