Single Malt Oat Whiskey

[still_stirrin]

...Do you think I could get away with adding the rolled oats in the beginning, let the malt enzymes convert them and skip the enzyme additions? Would this risk a gooey mash / stuck sparge?

If you run the rolled oats through the steps (temperature rests), it should reduce the glucans. So, I would definitely mash it all at once. And at the ratio you’re using, it won’t stick on you in the lauter tun. But it will be a little thinner when transferring to the fermenter...but I doubt that will be a problem, because that is your goal here.

You do still do an iodine check for starch conversion, don’t you?
ss

[Twisted Brick]

This got me very interested in an all grain oat wash. I just got a grainfather and am considering the following mash schedule for 4.5 kg of malted oats:

113 F - 45 C - beta glucanase rest for 45 min
129 F - 53,9 C - protease rest for 1 h
151 F - 66 C - 1 h
185 F - 85 C - add 1kg rolled oats + alfa amylase enzyme 1 h (instructions on my AA enzyme asks for optimal temp between 80C-90C)
135 F - 57 C - check pH < 5.5 + Gluco-amylase enzyme + 1h

I add the rolled oats for bump in ABV and do it seperately here with enzymes to get as complete a conversion as possible.

Do you think I could get away with adding the rolled oats in the beginning, let the malt enzymes convert them and skip the enzyme additions? Would this risk a gooey mash / stuck sparge?

From what I've read the rests are critical for raw oats and not needed (actually detrimental) with oat malt. Is this process for 4.5kg of malted oats?

[thecroweater]

Oat berries are a darn site easier to work with than rolled oats. Mashing rolled oats is only for the brave of heart and thick of brain. You just about want to steam mash it if using a significant amount of rolled oats as it turns to a dern thick porridge.

[Taxy]

Many thanks for your swift input.

@SS Wasn't planning to do an iodine check as I read that it doesn't work reliably with oats. Doesn't hurt to try, though.

@TB Yes, I just milled 4,5kg of malted oats (Fawcett). So you think I would be better off with a single infusion mash? At 66C (151F)?
Afterwards I could add the 1kg rolled oats and do the enzyme schedule.

@Crow You have been an inspiration for me to try oats and the oats/sugarhead I made, left me wanting more. In the oats/sugarhead recipe I converted 1,5 kg with my Polish enzymes (you'll find the link on HD search) I got a pretty good result: thin and sweet and relatively easy to sieve out after fermentation.
I could always convert the rolled oats separately as I did for the oats/sugarhead but then I loose perhaps the extra benefit of my Polish enzymes converting the remaining starches in the oat malts.

[thecroweater]

Look don't let me put you off, it is very doable but the challenges are very real. You could add more water for a lower gravity or work with a very thick mash that will thin down during the mashing. The last time I did one like this I did a full step and rest mash including one at I think 45"c which really did seem to thin things out from the get go. I'm a little under the weather (smashed as a western suburbs phone box) so I hope I am thinking straight to say that is a glucanase rest and the next is a proteinase rest say at 20 min each. That's if using malt, added enzymes will surely help as oat malt DP seems to vary a fair bit, Fawcett may have DP for theirs but homecmalted is anyone's guess from really good to sub par.

[Twisted Brick]

@TB Yes, I just milled 4,5kg of malted oats (Fawcett). So you think I would be better off with a single infusion mash? At 66C (151F)?
Afterwards I could add the 1kg rolled oats and do the enzyme schedule.

I temporarily lost function of my Mac, so I don't have access to all of my notes and cannot accurately cite the source (ADI?) where I read that rests are for raw grains only. There are any number of homebrew sites that recommend the same thing.

So without the supporting documentation, I can only offer you a fairly recent analysis of malted vs non-malted oats here. What's nice about this analysis is that it discusses mash characteristics of malted oats when raw oats are added, and the effects of enzymes on wort viscosity and yield under a given rest scheme.

Without direct experience like thecroweater, I would test your recipe two ways:

1) conduct a single infusion mash with the oat malt and step mash your raw oats separately on the stove top. This allows you to manipulate the water level/viscosity of the stovetop mash, hopefully making it more manageable

2) Step mash it all together

Looking forward to seeing your results.

[Taxy]

I did the mash yesterday, so I was too late to read about TB's suggested experiment.

Mash steps:
- added 4,5 kg oat malt to 18l water of 66°C - 1 hour
- heated mash to 85°C
- added 1kg rolled oats and AA enzyme - 1 hour
- cooled to 56°C, ph was 5.4 so ok for amyloglucanase enzyme - 1 hour
- sparged with about 8l of water.

When I added the rolled oats, the mash did turn quite thick but it quickly thinned out with the AA enzyme. The water cycling in the Grainfather never got stuck. Also the sparging went well. I guess the 4,5kg of (husked) malted oats made the mash loose enough for the 1kg of rolled oats. The wash tasted very sweet, almost like honey.

I was disappointed though with the SG. When the wash cooled to 25°C, I only had an SG of 1.034 (25 liters - 5,5kg of grains in total). I had hoped for a higher conversion because I first used the natural malt enzymes and then the extra enzymes (which worked well in a recent mashing).

Possible causes:
- Oat doesn't contain that much starch? I know there is less than in barley but I do not really know how much less.
- The rests had to be longer?
- I noticed that the oat malt husks are different from barley malt. When I milled them with my two-roller mill, the husks didn't crack while the inside kernels had been broken up well. Perhaps I should have cut the oat malts with a bladed mixer instead of milling them?

[Twisted Brick]

I did the mash yesterday, so I was too late to read about TB's suggested experiment.

Mash steps:
- added 4,5 kg oat malt to 18l water of 66°C - 1 hour
- heated mash to 85°C
- added 1kg rolled oats and AA enzyme - 1 hour
- cooled to 56°C, ph was 5.4 so ok for amyloglucanase enzyme - 1 hour
- sparged with about 8l of water.

When I added the rolled oats, the mash did turn quite thick but it quickly thinned out with the AA enzyme. The water cycling in the Grainfather never got stuck. Also the sparging went well. I guess the 4,5kg of (husked) malted oats made the mash loose enough for the 1kg of rolled oats. The wash tasted very sweet, almost like honey.

I was disappointed though with the SG. When the wash cooled to 25°C, I only had an SG of 1.034 (25 liters - 5,5kg of grains in total). I had hoped for a higher conversion because I first used the natural malt enzymes and then the extra enzymes (which worked well in a recent mashing).

Possible causes:
- Oat doesn't contain that much starch? I know there is less than in barley but I do not really know how much less.
- The rests had to be longer?
- I noticed that the oat malt husks are different from barley malt. When I milled them with my two-roller mill, the husks didn't crack while the inside kernels had been broken up well. Perhaps I should have cut the oat malts with a bladed mixer instead of milling them?

There's a a chart of yield (PPG) by grain type on the parent site here.

I just found this. The study is 7 years old and some of the results are interesting:

1) malt extract yield from malted oats is 62% vs 83% for barley. Under ideal mash conditions, the extract yield test for malted oats raised to 76%.

2) the study tested fermentability of malted oat wort over 8 different mashing regimes, concluding that a rest at 62C (143F) promoted the highest degree of fermentation.

3) mashing in at 35C (95F) was advantageous by 'pre-gelatenizing' enzymes that are then readily available when they get into optimum conversion range.

4) the test revealed that mashing by slowly raising mash temperature throughout the range (35C, 45C and 62C) did not convert as fully as the mashes that had distinct rest (temperature hold) periods.

So..... according to this study, malted oats benefit from rests, contrary to what the beer guys are saying.