Effect of mash pH on final product

[WilliamstonBrew]

Over the summer I brewed my first couple of all-grain batches. The efficiency was not great, so on the second batch I just used more grain. I got pH test strips for that second one, too, to try and isolate the problem. The pH was high, over 7.5, and only came down slightly during the mashing process.

The final product was, shall we say, not great. It wasn't infected, just tasted like cardboard and was too.... ick! Hard to explain. Bitter, and not in a hoppy way. Musty maybe? I actually had to dump out some bottles I couldn't stand it. I have 4 bottles still in the closet, I am not brave enough to open them but I'll test the theory that time can help. They're about 5 months in the bottle.

Which would have affected the outcome more:

1) pH out of range
or
2) the fact that I used three different base malts? (don't even remember what they were so no use asking)

 

[XXguy]

Did you do a starch conversion test with iodine?

7.5 is real high for a mash pH, what's the normal pH of your water? I'm going to assume you're using tap water. You probably need to do some testing to determine what kind of water you're actually mashing with.

You're probably going to need to learn about building your own water, or at least diluting with distilled water to get a decent profile. Probably best if you do some reading on water at howtobrew.com
http://www.howtobrew.com/section3/chapter15.html

Without the right pH, you're not going to get the good enzyme activity you need to break down the starch and properly convert to sugars.

 

[WilliamstonBrew]

I didn't do an iodine test, instead I used my refractometer to test the mash every so often. I was basically 6 points off my target OG for the recipe, which I consider to be a pretty big error. Temps were not the factor, I used a digital probe thermometer and kept it within perfect range for conversion.

I was in fact using tap water. The normal pH is around 7-8.

I am a bit lazy (which, for all grain brewing, basically means I don't do it often!) so would it be easier to use one of those pH stabilizer packets? My LHBS doesn't have the beer ones, just a 4.5pH one... for wine I think... would that be too low?

 

[XXguy]

"normal" pH for tap water is around 7-8... and that would normally give you a good pH in the range of mid 5's for mashing. If your mash reading was 7.5.... either your water is well above 8 to start with, or your test strips were FUBAR'd. From what you described in the taste of your beer, I'd guess your mash pH was really high and you had lots of unconverted starch in your wort.

Read the link above. Just adding stabilizers and additives without knowing the kind of water you have probably isn't going to fix the problem, and might cause you some other grief. Better to test & know, than to poke and hope.

 

[TimWeber]

Did you let your sample cool before using the pH strips? Most of them are to be used at ambient temperature. a pH of 7.5 after the grains were added does not sound right to me. When I check after mashing it, if I don't add brewing salts, I have a pH around 5.8. Remeber pH is on a logarithmic scale, a difference between 5.4 and 7.5 is huge.

Carboard is usually oxidation.

That weird bitterness may be due to your tap water. We usually balance with gypsum when making a hoppy beer. Get a local water report and take a look at How to Brew by Ray Daniels.

 

[WilliamstonBrew]

Excellent, I will read up and educate myself further and do the science. Thanks for all the quick input, guys!

 

[AiredAle]

What kind of tap water are you using? Well water or surface water. Typicall well water is more alkaline than surface water. The pH of the water is irrelevant. The alkalinity of the water is paramount. If you have highly alkaline water, that is water with a lot of bicarbonate present, and you are making a light colored beer, you will have problems with the mash pH. The buffering ability of the bicarbonate will overpower the ability of the mash to drop the pH to the desired 5.2-5.5 range. You will need to treat high alkalinity water to reduce it. There are lots of ways to do this. There are lots of threads on this forum that will help you sort out your water issues. Go to the brewing science pages here and start reading. Also, the John Palmer book, "How to Brew" is very helpful at walking you through the arcane and complex world of brewing water.

Also, without looking it up, the temperature differential in pH measurements is in the range of 0.3 or so pH units for the pH and temperatures you are talking about. So, if you measure at 70 F and you get a number of 5.5, that number will be 5.2 at 155 F.