PM ratio of base grains to adjunct

[shughes]

I am considering doing a Oatmeal stout PM and still researching the brewing process. I have one extract brew under my belt and numerous batches of wine/mead. I am taking a look at the PM approach and trying to figure out more on the mash process when using flaked oatmeal in mash. I have noticed pm kits with oatmeal usually have around half the oatmeal that all grain recipes use and have assumed its due to the need to have a certain amount of base grain to help the conversion process. I found this one BYO article getting close to my answer:

http://***********/component/resource/article/511-countertop-partial-mashing

Under the "Four pounds of grain" the author states that you can do 13oz of adjunct grain using 2 row and up to 19oz if using 6 row but does not state how those numbers are calculated. Is there a formula or general guideline of how much base grain is needed for a certain amount of adjunct? I would like to convert a AG Oatmeal stout recipe which uses around 1-1.5lbs of oatmeal.

 

[Bobby_M]

This should answer your question... eventually.

 

[Bob]

Under the "Four pounds of grain" the author states that you can do 13oz of adjunct grain using 2 row and up to 19oz if using 6 row but does not state how those numbers are calculated. Is there a formula or general guideline of how much base grain is needed for a certain amount of adjunct? I would like to convert a AG Oatmeal stout recipe which uses around 1-1.5lbs of oatmeal.

I don't know how they arrived at those numbers. Large breweries consistently use upwards of 50% unmalted adjunct - usually in the form of corn or rice - with six-row malted barley with no problems with conversion. Even two-row will convert an equal amount of unmalted adjunct, given good mashing techniques.

There's the problem in your specific case, IMO. I think you should have some mashing experience before you go adding two possibly negative variables (relatively large amounts of unmalted adjunct and hull-less grains). That's not to say you can't be successful with a mash consisting of, say, 3 pounds of 2-row and a pound of flaked oats. It's just saying it's bringing in variables a beginner might be ill-equipped to resolve.

Tell you what - avoid the issue entirely! Do what I do and use oat malt instead of flaked oats. You get all the flavor/mouthfeel/whatever benefits of flaked oats and avoid both variables, because it's malted and it's got hulls.

If your LHBS can't get Fawcett's Oat Malt for you, Northern Brewer has it in stock for mail-order. Just make sure your LHBS can reset their mill to get a good crush (the corn is smaller than barley or wheat).

Cheers!

Bob