Water Chemisty Primer question: Use acid malt if adding dark grains at vorlauf?

Hey all...

I've been having an astringent off flavor in some of my beers (especially the pale ones), and I'm going to start using RO water to see if my tap water is the problem.

I'm about to do my first batch using 100% RO water, and it's a porter. I know the primer says to skip the acid malt if using dark/roasted grains, HOWEVER I'm going to add the roasted malts at vorlauf (instead of the main mash) to get a mellower, less burnt character from them. My thought is that since I'm only mashing my base malt and some crystal (and thus won't get the acidification effects of the roasted grains), I should treat this like a pale beer and add 2-3% acid malt to the grist that will be mashed. Is this the "right" way to do it?

Thanks for your help!

 

I'd say so. Acid must be provided in order to lower mash pH into desired range. Ordinarily most if not all of this in a dark beer comes from the dark malts. If you do not use the dark malts until later then you must get this acid from somewhere else. i have never done this but many swear by it. My fear would be that if you got mash pH to the lower end of the desired range and then added more acid at vorlauf (in the form of dark malt) that you could push the pH too low so I'd use a little less that the recommended amount of sauermalz i.e closer to 2% than 3.

 

Thank you, sir! That's what I was hoping to hear!

 

I'm actually suggesting the opposite.

Most pale malts have a DI water pH around 5.7-5.8. With some crystal malt your pH should be around 5.6. For every 10 SRM you are getting from crystal malt the mash pH drops by about 0.15-0.2 pH units. So there is a good chance that your mash pH will be between 5.5 and 5.6, which is optimal for mashing (pH for best fermentability is 5.4-5.6 and pH for best extract yield is 5.55-5.75). One of the reasons why a lower mash pH target is recommended (5.3-5.4) is because sparging tends to raise pH and w/o aiming for a lower pH target, the kettle boil pH may end up being too high. But since you are adding dark grains at Vorlauf and you are using R/O water, the pH is actually expected to fall. Thus aiming for a slightly higher mash pH is fine.

In essence, you are brewing a Porter with low alkalinity water. I don't think you need any acid malt unless you want it for flavor.

Kai

 

What you really should do is is obtain a pH meter and check the pH of the mash making adjustment as required to subsequent brews of the same beer. The correlations between color and mash pH are tenuous at best and even were they tighter how do you know that the color of a congress wort made with malt from a package labeled 150L will be 150L? Does anyone know what the tolerance is? Is it 150 ± 0.2 L or is is 150 ± 30L or some other number. Beyond that there is appreciable variability in both DI mash pH and buffering capacities between different cultivars, batches and maltings for what is nominally the same grain. Thus it is hard to predict mash pH accurately and, even if you check it, control it precisely without making adjustments. But if you buy the same malts from the same source, treat your water the same way etc. the pH should be within reasonably tight bounds from brew to brew. That's why it is important to have records (IMO anyway) of pH in your log. Please note that I do not predict that the use of the Primer guidelines will give you any better mash pH predictions than any other method because they are subject to all the vagaries I mentioned above and don't even attempt to consider the effects of color beyond the very broad distinction between light and dark beers.

Optimal pH for extract and optimal pH for fermentability are fine concepts but you are shooting for neither. You are shooting for optimality of beer quality and quality is a broad term because there are various definitions of optimality ranging from best sales to most pleasing to your SO. Again, records are the key to finding what that pH is. If you have a batch that mashes in at 5.5 and think it's better, by whatever your optimality criterion may be, than the previous batch of beer you brewed that came in at 5.6 then shoot for closer to 5.5 in the future. In my own brewing I found that hitting that sweet spot was like turning on the lights. The beers went from good to great (by my optimality criterion which is that I and my guests like it).

Obviously the driving force behind the Primer is simplicity and it should get you in the ballpark. I won't say you need sauermalz and I won't say you shouldn't be mindful of what Kai is saying but I do think the chances are good that you will get some improvement from the use of a bit of it. I don't think flavor (other than the 'brighter flavors' that arise through pH control) is going to be a factor. Sauermalz does contribute flavors but they are very nuanced in delicate lagers. I doubt you'll notice them at all in a Porter.

 

I think this is exactly what I'll do. If I'm going to start working with my water chemistry, I should do it right. That means taking measurements instead of making estimates. Now I just need to find a reliable and accurate pH meter that won't cost an arm and a leg.

As it happens, I ended up changing my plans at the last minute and brewed an IPA instead of the porter (using the primer's recommendation for British beers). Once I get my pH meter, I think I'll do a small stove-top mini-mash experiment on the effects on mash/sparge pH of adding dark grain @ vorlauf.

Thanks again to both of you for the feedback.

 

Here is done advice I have on buying pH meters for brewing: http://braukaiser.com/wiki/index.php?title=PH_Meter_Buying_Guide

In the interim, I think you should be fine either way. The differences of pH we ate taking about here are not going to ruin your beer.

Kai