Thursday, August 2, 2007

Ph

Here is a response to a question from fellow brewer/blogger Travis in Syracuse, NY. In my post about the Matrimony Ale, I talked about how the mash Ph was "bi-polar." I would take Litmus tests before and after additions of gypsum (Calcium Sulfate...calcium ions help to lower the mash Ph). Every time I'd add it, I'd get an acidic reading. Then after about 10 minutes, the litmus strip showed up red again...basic.

All-grain brewing requires one critical and initial step...the MASH. Its where all the grains are mixed with hot water, and allowed to rest at a given temperature for about an hour. During this "saccharification" period, enzymes in the malted barley grains become active and convert grain starches into food for yeast...fermentable sugars!

The mash can either be looked at simply, or more complex. In its simplest form, mixing hot water with grains will most likely result in a fermentable wort. How "fermentable" is the question.


In it's complexity, the mash is a sensitive thing. There are many variables contributing to the overall efficiency and activity of the grain's enzymes. The main variables are temperature, grain bill, acidity/mash Ph, and alkalinity.

I really like how John Palmer covers this topic in his book How to Brew.

Here in Chicago, I've noticed that my mashing come out fairly acidic. So their really isn't much I need to do to the water. When I dilute it with distilled water, in order to lower the Bicarbonates for certain styles, then the mash Ph will turn basic because the level of Calcium is also diluted. In this case I figure out how much Gypsum or Calcium Chloride to add in order to bring the Ph down/more acidic.

How much to add? It's not a matter of where the Ph will be. I look at the level of Sulfates or Chlorides that is more appropriate for a particular style. If I want more hop presence...more Gypsum. If I want more maltiness...more CaCl2.


Chicago Water Profile:
(Ca:34)(Mg:11)(Na:6)(SO4:25)(Cl:11)(HCO:106)
New York Water Profile:
(Ca:13)(Mg:4)(Na:11)(SO4:12)(Cl:21)(HCO:29)

In an Excel spreadsheet, I add to the base water (sometimes base is diluted w/ distilled) profile incremental additions of salts to get close to a profile that aids in the production of specific regional styles. A good gram scale helps in measuring salts on brew day, or simple measuring spoons will to just fine. Ever since I've been tinkering with salts and diluting with Distilled, I've noticed that the overall beer taste has gotten better...or at least more distinct.

Travis, if your water in Syracuse, NY is like the above example, you have a pretty darn good water profile. Fairly soft with low Bicarbonates...great starting point for all styles. You can definitely make some great pale lagers! If you are reading levels that are too basic, you will definitely need to add some Gypsum or Calcium Chloride (or combo) or acids/acid-malt to increase the level of Calcium Ions in the mix. Just try it, take litmus readings, and note any differences compared to a beer with more, less or no minerals with a similar malt bill.

Overall, I think its important to get into the habit of checking mash Ph every time you brew. Not so that it can be corrected in the moment, but it will provide good information when planning upcoming brews.

Calculating efficiency is kind-of complex. There are a lot of factors that play a role, and I'd say too many to narrow in on just one right away. Part of it is getting the gravity readings correct and pre&post boil volumes correct. As far as Ph litmus strip readings are concerned, it's important to take the reading at a cool/room temperature. Also, I'm under the impression that it takes a little while for the Ph of the mash to settle as well.

In the very end, if your iodine conversion test comes out positive, then sparge away! I have noticed that some conversions were much more "sticky" than others, but haven't recorded which ones. It's happened a number of times, and I'll take better notes next time it happens.

Not sure if I've helped any. But I think its worth getting into. Eventually we'll make sense of all this. In the mean time, the beer tastes great, and I'm not too worried.

4 comments:

Brian said...

Great stuff! This will be interesteing to wade into the topic of PH a bit more with my first all grain batch coming up.

Enjoyed reading it, thanks for the great info!
Brian

Travis said...

Ted,

Thanks for the post, that was just what I was looking for. I am going to print out that and the excellent (as always) Palmer bit. I figure before my next batch, I am going to go over everything and come up with a game plan.

That's good stuff, as always. Thanks a lot, I will keep you posed on how it goes.

Cheers! Be careful of the wind out your way.

Ted Danyluk said...

Thanks guys.

Its just a matter of time before the science side of AG brewing becomes interesting and applicable. I really didn't care much about it until I was dabbling into water salts for certain styles.

I use 2 litmus strips...the yellow strip and an orange one with a much greater range. I figure two strips are better than one, and they usually work well to give a more accurate figure.

Sometimes I stir the mash every 15-20 minutes, so I take a tablespoon out for Ph tests. About half way through I start checking for conversion. Conversion is fun to watch. It will show dark, and then after another 20 minutes it will show red. When its red you can start preparing for the sparge.

I still don't have a good way of recording it, so get into the practice of writing a good log. Why take readings if there's no record for the future...otherwise its just for instant gratification or disappointment.

Travis said...

Ted,

So I am getting ready to brew a Brown Ale. My understanding is that the best water profile to go for is the London water profile. This is what the plan is based on that:

My Water:

Name: Syracuse, New York
PH: 7.1

Calcium: 31.0
Magnesium: 11.0
Sodium: 17.5
Sulfate: 27.0
Chloride: 27.0
Bicarbonate: 0.0

I plan on treating this with 1/2 (2 grams) teaspoon of gypsum and 1 teaspoon (4 grams) of baking soda. That should (according to what I have) give me this:

PH: 7.1

Calcium: 55.8
Magnesium: 11.0
Sodium: 75.1
Sulfate: 86.2
Chloride: 27.0
Bicarbonate: 151.2

Does this sound right? Should I add these brew salts directly to the mash?

Thanks.

Travis