Oatmeal Not Converting

[North_of_60]

I've made several Oatmeal Stouts using grocery store oatmeal and never had a problem with hitting my projected OG. I spread the oatmeal out on a cookie sheet and roast it at 300 degrees for 15 minutes, add it to my mash and it's always been fine. I have read that all oatmeal is made by steaming the grains before rolling so they should mash when add with other malted grains.

Two beers ago I forgot it in the oven for 45 minutes and it got dark roasted. My OG was down exactly to what it would have been without the oatmeal. I had expected it to be low. The beer is drinkable but not great. I think the burnt oatmeal contributed to the not great.

I made another batch Friday using Quaker Old Fashioned Oatmeal. I have read on forums that some brewers just put the oatmeal in without roasting or preboiling so I thought I'd try that. No good, missed my OG by .011.

The only other difference is that I used Planet Pale Malt (Muntons), for my base malt on the last two.

Grain Bill:

10 lbs Base Malt
2 lbs Oatmeal
2 lbs Caramel 40
12 oz Chocolate Malt
8 oz Black Barley

I mashed for 90 minutes, started at 155 degrees was down to 153 after 90 minutes. I gave it an extra 30 minutes mash for the oatmeal.

Estimated OG 1.075
Actual OG 1.064
Estimated OG without Oatmeal 1.065

So, what is going on here?

 

[BigEd]

The "old fashioned" oatmeal unlike the run of the mill stuff is probably not gelatinizatized. That said oats have a fairly low gelatinization temp than many other grains, 60C/140F should do it. Maybe next time giving it a prior mini cereal mash and then going to main mash would help.

 

[bracconiere]

I have read that all oatmeal is made by steaming the grains before rolling so they should mash when add with other malted grains.

as far as i know the starch in oats gels at mash temps, just like barley & wheat...

i'd take at stab 'at a guess'...oats are gummy, maybe sparge effec? maybe a protein rest would help?

 

[CascadesBrewer]

The "old fashioned" oatmeal unlike the run of the mill stuff is probably not gelatinizatized.

Everything I read is that Quaker Old Fashioned Oats are almost the exact same thing you get at the homebrew shop and that Flaked Oats and Rolled Oats are names for the exact same thing. I did see one BYO article saying that Quaker Oats has a higher fat content than oats selected specific for brewing and can go rancid. All I can add is that I switched to using Quaker Old Fashioned Oats since it is cheaper and I have not seen any difference vs the oats I got at the homebrew shop.

So, what is going on here?

I am sure the roasted oatmeal would add that flavor. As far as gravity?? I could see where the roasted one may have impacted the starches and gravity points, but it is an area I don't know much about (Chocolate malt is very roasted and it adds gravity points). I cannot see where there would be a difference between lightly toasted and straight from the can. Even if your grain has a much lower diastatic power, it still should have plenty and you mashed for 90 mins.

 

[day_trippr]

fwiw, I have switched to using malted oats where I used to use flaked, and other than easier lautering (oats have husks! winning! ) have observed no change in gravity from the flaked recipes. I do have to use a tight grind, however - .025" gap on my old BC mill - and even so I have been running the oats through twice to make sure they're pretty well busted up...

Cheers!

 

[bracconiere]

fwiw, I have switched to using malted oats where I used to use flaked, and other than easier lautering (oats have husks! winning! ) have observed no change in gravity from the flaked recipes. I do have to use a tight grind, however - .025" gap on my old BC mill - and even so I have been running the oats through twice to make sure they're pretty well busted up...

Cheers!

my experience brewing 100% oat malt beer. their like 50% husk, and i milled at .018"

 

[day_trippr]

Saves on rice hulls!

 

[bracconiere]

Saves on rice hulls!

good tip for people that like wheat beers...

 

[day_trippr]

Wait - what?



Cheers!

 

[North_of_60]

Thanks for you replies. I first posted this in BIAB because that's the method I use, but the moderator moved it over here. I don't have to deal with rice hulls. But I do need to be concerned about dough balls and I am very careful to avoid them. I crush the grains at .025 and have had good results with that on many other beers.

I'm stumped. I've use the Planet Pale Malt for a blonde and an amber and hit my OG within a point or two. But, my last two Oatmeal Stouts I have missed by .011 almost exactly the same as the Oatmeal contributes.

 

[bracconiere]

Wait - what?



Cheers!

my heads spinning, today there was someone, that had bad effec, someone with an off flavor in a wheat beer extract, and this thread about oats....

sorry they just blended together... just thought, if you use some oat malt, in a wheat beer, you'd get better effec....but the wheat beer was extract, and the one about bad effec didn't use wheat....

 

[MuntonsJasonC]

I've made several Oatmeal Stouts using grocery store oatmeal and never had a problem with hitting my projected OG. I spread the oatmeal out on a cookie sheet and roast it at 300 degrees for 15 minutes, add it to my mash and it's always been fine. I have read that all oatmeal is made by steaming the grains before rolling so they should mash when add with other malted grains.

Two beers ago I forgot it in the oven for 45 minutes and it got dark roasted. My OG was down exactly to what it would have been without the oatmeal. I had expected it to be low. The beer is drinkable but not great. I think the burnt oatmeal contributed to the not great.

I made another batch Friday using Quaker Old Fashioned Oatmeal. I have read on forums that some brewers just put the oatmeal in without roasting or preboiling so I thought I'd try that. No good, missed my OG by .011.

The only other difference is that I used Planet Pale Malt (Muntons), for my base malt on the last two.

Grain Bill:

10 lbs Base Malt
2 lbs Oatmeal
2 lbs Caramel 40
12 oz Chocolate Malt
8 oz Black Barley

I mashed for 90 minutes, started at 155 degrees was down to 153 after 90 minutes. I gave it an extra 30 minutes mash for the oatmeal.

Estimated OG 1.075
Actual OG 1.064
Estimated OG without Oatmeal 1.065

So, what is going on here?

Our Pale Malts are designed for all-malt grists, or grists with small amounts of adjuncts. Planet Pale has an estimated Diastatic Power of around 50 deg L, so the DP of your grist is 41.2 which is close to the minimum DP of 40 for a mash to convert itself. Since you're mashing a bit high temperature wise, you're getting more alpha amalyse which isn't helping convert the unmalted oats.

There are a few ways you can go:

• Adjust your mash temps to get more beta amalyse. I'd actually suggest a step mash here to ensure full conversion, like 144F for 20 mins, then 156 for 40 mins. There's a prominent Irish craft brewer that uses a step mash to convert the flaked barley in their stout.
• Replace some or all of your oatmeal with malt. Oat Malt is more widely available now than ever. Last spring I replaced half of my flaked barley in my Extra Stout with wheat malt which worked great.
• Replace 1lb of the Planet Pale base malt with a higher enzyme base malt like a Lager Malt or a North American 2-row.

 

[North_of_60]

Our Pale Malts are designed for all-malt grists, or grists with small amounts of adjuncts. Planet Pale has an estimated Diastatic Power of around 50 deg L, so the DP of your grist is 41.2 which is close to the minimum DP of 40 for a mash to convert itself. Since you're mashing a bit high temperature wise, you're getting more alpha amalyse which isn't helping convert the unmalted oats.

There are a few ways you can go:

• Adjust your mash temps to get more beta amalyse. I'd actually suggest a step mash here to ensure full conversion, like 144F for 20 mins, then 156 for 40 mins. There's a prominent Irish craft brewer that uses a step mash to convert the flaked barley in their stout.
• Replace some or all of your oatmeal with malt. Oat Malt is more widely available now than ever. Last spring I replaced half of my flaked barley in my Extra Stout with wheat malt which worked great.
• Replace 1lb of the Planet Pale base malt with a higher enzyme base malt like a Lager Malt or a North American 2-row.

Thank you for clearing that up for me. I had not considered the DP of Planet Pale when I designed the recipe. It makes sense now.

Al