I’ve avoided malting oats after reading in the “Homebrewers Garden” by Fisher and Fisher that germinating oats attract “butryfying bacteria” and that the butanol isomers that these bacteria can produce are poisonous as are the microbes themselves. But I still can’t find any other sources of information to back up this claim, and please correct me if I’m wrong here but I don’t think butryfying is even a word. If you have any information on this subject please let me know, you could be saving my life! What does give me some cause for concern is Ergot which is found most often in rye and oats, but ergot is easy to spot in whole grains because it’s black and looks like a mouse turd. It’s impossible to spot once it’s ground up though.
I recently picked up a 40 lb bag of oats at a feed store for $13. It was surprisingly clean, much cleaner than any feed barley I’ve bought. I only rinsed it twice and that seemed sufficient. What I soon discovered with oats is that they absorb water much faster than barley. I discovered this by actually overshooting my target moisture content twice!
I started by finding out the initial moisture content by drying out a ground 1 ounce sample in the oven at 225F for 3 hours. The initial moisture content was 12%. I also tested the germination rate between some damp paper towel and I got a 95% germination rate which was pretty awesome. For the first batch I made mathematical errors while weighing it and I ended up steeping it for too long. It reached 47% which I malted anyway but I got a surprisingly low germination rate at 62% The malt was very wet for a long time during germination, the surface of the grains just wouldn’t dry out like barley does. So I did another batch and after only two steeps at 8 hrs with an 8 hour rest in between, it was still too high at 44%. The germination rate improved to 72% So why not try again. It turns out you can reach 40% with just one steep at 11 hours and my germination rate improved yet again to 81.5% which is ok, not great, but I’ll take it. Makes me wonder what say 36-38% would produce. The added advantage to steeping just once is less risk of mould forming. This third batch did not have any visible mould by the end of germination whereas the other two had some ( not a lot, I picked out most of them). The oats had an unpleasant smell throughout the process and it should be noted that it was present even before germination, and before any visible mould forming. When oat husks are wet they smell exactly like green corn husks and it’s quite strong too, so much that I almost chucked all three batches. This green corn husk smell is very similar to and can be mistaken for a musty odour – like a mouldy wet basement. Having that show up in my beer well, that’s kind of a deal breaker. It also made me kind of paranoid to think that I could be ingesting something poisonous. I’m not sure why I got such a high germination rate without steeping in the test sample compared to the steeped batches. Perhaps oats do better with spraying water during germination instead of steeping.
I ended up making a lager malt since I planned to make a lager out of these oats using the second and third batches of malt. It’s not something I’ve seen before and I thought it would be a good way to really find out the flavour characteristics of oats. What I soon discovered is that people don’t make oat lager for a very good reason, it’s gross. I added some lightly toasted oat malt to the recipe and those tasted great. It made me think that perhaps dark beer made with a Vienna oat malt as a base would be able to mask the corn husk flavour. I’ll try this next.
After primary fermentation the corn husk flavour was still there but decreasing slightly. I threw in some Citra hops in an attempt to mask some of the flavour and it kind of worked. Needless to say this beer is not what I expected at all so I’m not quite sold on it yet. It’s an acquired taste, but if someone gave me this beer and said that it’s made using the ancient Mayan technique of filtering through green corn husks I would say ” WOW, this beer is AMAZING, you can actually taste the corn husks!” But there is no ancient Mayan technique, so I can’t even lie about it. The first thing you notice is the Citra hops, which are always nice, then for me, the husk flavour starts at the back of my throat – I know gross -perhaps due to the tannins? not pleasant. Once it rears it’s ugly head the husk flavour kind of takes over or this could be just a mental thing – as in, I can’t get away from tasting it when I really don’t want to. But like I said before, if you can embrace the husk flavour (perhaps you also like eating grass) then this beer is fantastic!
- 11 lbs. Oat malt
- .5 lbs Oat biscuit malt
- 5 oz acid malt (store bought)
- 1 oz Goldings (5%) 60 min
- 1 oz. Goldings 15 min
- 1 oz. Centennial (10%) 5 min
- 1 oz Mandarina Bavaria last minute
- 1 oz Citra last minute
- 2-3 oz (can’t remember) Citra dry hopped 7 days
Mashed in at 105F at 1.0 qt/lb and added direct heat to 130F for 20 min. Then added an infusion of 1 gal. to get to 145F at 1.42qt/lb for about 30 min. I then decocted a gallon to get to 154 for another hour and a half.
Original gravity was 1.050 Final gravity was 1.0064 for 5.5% abv.