I've been wanting to brew gluten-free and all grain for a while. My initial experiments trying to malt millet and use it as a base malt were a bit discouraging, yielding starchy breakfast porridge rather than sweet wort. Then I came across some posts on the Aussie Homebrew forum about using enzymes to mash unmalted grain. I've done one initial test mash that is promising, so here's how my thinking is developing about this, and what I hope to try next...
First the enzymes. You need two, the first is Alpha Amylase, and the second is Gluco-amylase (aka alpha-glucosidase). These are sold by a few online distributers:
- Mile Hi Distilling
has them in 1 lb amounts sold as BA-100 and GA-100
also sells both of these, they seem to be the same as Mile Hi's, and you can get them in 1lb or 2oz amounts. homebrew4less.com also redistributes these same enzymes from brewhaus.com
How to best use these enzymes?
Package instructions say the following:
Amylase Enzyme is for converting starch into complex sugars and is most active around 152-158F
Gluco-amylase Enzyme is for converting complex sugars into glucose that yeast can eat and should be added at room temperature.
I don't think this is the complete story. Info from bevenovo.com (which may or may not be the same product) suggests there is more to it:
- working range is pH 5.5 - 8 up to 230F
- optimal range is pH 6 - 6.5 at 194F-212F
- Ca (calcium) concentration at 50-70 ppm is optimal
- working range is pH 3.0 - 5.5 at 104-140F
- optimal range is pH 4 - 4.5 at 136-140F
So after pouring through the Mash chemistry chapter of Palmer's How-to-Brew, here's my proposed mash schedule
1. Crush raw, unmalted grain (corona type mill works better than roller mill with most gluten-free grains, which are smaller than barley) and mash in fairly thick so you can add water to cool mash later
2. Beta-glucanase rest at 112F for 20-30 min (helps break down "gumminess")
3. Protein rest at 122F for 15-20 min
4. Add alpha-amylase enzyme (0.4-0.8g per lb of grain)
5. Raise mash temp high enough to gelatinize grain (167-180F) and hold for 10-15 min
6. Cool mash to 156F and hold for 30 min to activate alpha-amylase enzyme (may be able to skip this step if enzyme is really working well at higher temps, according to bevenovo information)
7. Cool mash to 138F
8. Add Gluco-amylase enzyme (0.5-1g per lb of grain) and hold 138F for 30 min to activate gluco-amylase enzyme
8. Mash out at 168F and lauter as normal; you will probably want to add rice hulls, depending on your crush and if your grain had any husks.
There's a document out there by Andrew Lavery that details a similar gluten-free mash schedule, if you search around on the Aussie Homebrew forums. His process is for malted grain and does not use added enzymes, but has you decant the top liquid off the mash to preserve the enzymes before boiling the mash, and then adding the decanted liquid back in after you've brought the mash temp back down below 160F.
Anyone want to try this with me? Here we go...