Estimate for oat mash pH?

[rhys333]

Hey everyone,

I'm brewing a oatmeal brown ale and I'm wondering how I plug oats into the water calculator. I may do a very light toast in the oven, but I'm guessing this won't bring it into the roast/toast malt pH range. If I categorize it as two-row base, would this be a reasonable estimate? Thanks in advance.

 

[MikeInMKE]

+1

Also, would be nice if you could select a BJCP style in Bruin Water, and get the target values.

I brewed an oatmeal stout last weekend, and for lack of any better options chose "Black Malty" which I fear was way too soft for an oatmeal stout.

 

[rhys333]

Does anyone have insight on this?

 

[SevenOaks]

I found this response to the same question from a general internet search:
https://www.homebrewersassociation.org/forum/index.php?topic=6696.0

So, it looks like they should be treated same as base malt.

 

[ajdelange]

Which base malt? Here are the properties of some base malts (and flaked barley). The first number is the DI mash pH (room temperature) and the second the buffering at DI mash pH

Weyermann Pils: 5.63/40.7
Weyermann Floor Pils: 5.85/31.3
Crisp Maris Otter: 5.69/ 46.6
Muntons Maris Otter: 5.84/46.1
Flaked Barley: 5.64/36.2

So looks as if you need to measure the DI water mash pH (easy enough to do) and WAG the buffering at 40 mEq/kg (the average).

 

[rhys333]

I found this response to the same question from a general internet search:
https://www.homebrewersassociation.org/forum/index.php?topic=6696.0

So, it looks like they should be treated same as base malt.

Cheers, I ended up stumbling across the same link last night. Am I right the posting is from the creator of Bru'n?

 

[SevenOaks]

Good question, ajdelange.

Where could one find this detail for more of the different grains than the calculators make use of?

 

[ajdelange]

Someone has to make the measurements. The only logical person to do that is the maltster as he's got his stuff in the lab for other measurements anyway. These data should, IMO, be part of every lot's analysis. It is impractical for anyone else to do this as he would be overwhelmed by the volume of lots and the amount of work required to characterize one malt.

 

[rhys333]

In the absence of solid data, what observations are people making with oats in the mash? I heard rumor of a measured pH 0.1-2 lower than estimated when categorizing oats as base malt. I'm unsure which base, though I assume US pale 2-Row. I'll don't have the links unfortunately but will post if i can dig them up.

If I had me a pH meter (I know, I need one) I might try doing a tiny mash in distilled water with the same proportions of base to oats.

 

[ajdelange]

If someone could get the DI mash pH then you could assume that the buffering is about 40 and given that one wouldn't use more than a fairly small percetage (?) of oats the error from not knowing the buffering exactly should be small. Now all you need is a program that lets you enter DI mash pH and buffering or at least one that tells you what assumptions are made for Pilsner malt, ale malt, Munich I etc so that you could choose the one that matches best.

 

[rhys333]

Well I thought I'd follow up on my original question regarding oat pH...

I bottled an oatmeal brown ale last night and unfortunately there's a nasty bitterness/astringency right out of the fermentor. I'm guessing the oats pushed the pH significantly higher than anticipated, extracting tannin from the grain. I used MO base with about 1lb C70, 0.45lb Chocolate (pale/reg mix), and 0.8 lb toasted rolled oats. I hedged my bets between EZ Water and Bru'n estimates, treating RO water moderately with CaCl2 plus a dash of baking soda.

I'll leave it conditioning for a few weeks, but I've seen this before and I might have a dumper here Darn my all-grain woes. Seems I can brew pale ales no problem with RO and salts, but the darker beers are proving troublesome.

 

[ajdelange]

If the oats were toasted I doubt they would raise the pH of the mash. I have no doubts that the bicarbonate would though. You can, in general, tolerate up to about 20% dark malts before any alkali is required. For years I railed here against the unnecessary addition of chalk to beer. Now I'm railing against the unnecessary addition of sodium bicarbonate.

If the problem was indeed tannin extraction from grain husks that will eventually complex and settle out.

 

[rhys333]

Thanks AJ. I rarely chill my bottles for any length of time due to limited fridge space, but I recently left 6 bottles chilling for a week with interesting results. The chill haze dropped out completely, taking all the nasty bitterness along with it. After ruling out other factors, I'm thinking tannin extraction due to high pH is the most likely cause.

I added the baking soda against my better judgement. I'm learning from trial and error that going with the lowest estimate in the EZ speadsheet seems to works best with my system. I wasn't aware I could add up to 20% dark malt before alkali is needed, but will keep this in mind going forward.

Austin.

 

[rhys333]

One last follow-up regarding the bitterness/astringency I've been experiencing with darker beers. After looking through my process I've identified one other possible (and highly likely) contributor. The bag of Fawcett chocolate malt my LHBS sold me is labeled at 550L. I did some research and Fawcett chocolate is supposed to be 325-400L! What I likely have here is black patent incorrectly labeled as chocolate.

 

[troxerX]

Good question, ajdelange.

Where could one find this detail for more of the different grains than the calculators make use of?

This link will probably answer your question, long read but worth it, one of the most informative and helpful I’ve seen when it comes to this subject..

https://braukaiser.com/wiki/index.php/Mash_pH_control

 

[Silver_Is_Money]

A 100% Malted Oat based Congress Mash (I.E., Mashed in DI water) has a mean pH of 5.9. (page 412, lower right)

A chart within the same source shows three varieties of malted Oats spanning 5.88 to 5.99 pH_DI. So 'perhaps' ~5.93 is a valid 'nominal'.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.2011.tb00487.x

A nominal 100% Oat Malt 'BC' (buffering capacity, as expressed in units of mEq/Kg_pH) is however unknown (by me at least). Just as for pH_DI, the Malted Oat 'BC' will not be the same as for Flaked Oat (which is not malted/sprouted).

 

[Silver_Is_Money]

I believe (subject to correction) that the general trend is for malted grains to exhibit lower pHDI and higher BC vs. the same grain when unmalted.

 

[troxerX]

I believe (subject to correction) that the general trend is for malted grains to exhibit lower pHDI and higher BC vs. the same grain when unmalted.

That’s what the data shows. Crystal malts are the most acidic as they are kilned when wet while roasted malts are not that acidic, opposite as most people will think, given they are kilned dry. That read I attached above explains that and shows distilled water mash pHs for different single malts and grist combos. Here is the link again.

https://braukaiser.com/wiki/index.php/Mash_pH_control

 

[VikeMan]

Crystal malts are the most acidic as they are kilned when wet while roasted malts are not that acidic, opposite as most people will think, given they are kilned dry.

Dark roasted malts tend to be more acidic than the light crystal malts and less acidic than the dark crystal malts. And/but "per lovibond" they are definitely less acidic. It's the main reason I dislike pH models based simply on color.

 

[troxerX]

Dark roasted malts tend to be more acidic than the light crystal malts and less acidic than the dark crystal malts. And/but "per lovibond" they are definitely less acidic. It's the main reason I dislike pH models based simply on color.

Exactly, you summarized it much better, what I meant was that just by being ‘roasted’ doesn’t mean that will be the “most” acidic as there will be crystals that are not closed to be roasted but still more acidic than roasted… if that will ever make sense!

 

[Silver_Is_Money]

Exactly, you summarized it much better, what I meant was that just by being ‘roasted’ doesn’t mean that will be the “most” acidic as there will be crystals that are not closed to be roasted but still more acidic than roasted… if that will ever make sense!

It clearly makes sense to model Caramel/Crystal malts separately.