Dutch processed cocoa powder raised kettle ph very high

[Colbizle]

I brewed a chocolate milk stout last night and on flameout I mixed in a pound of lactose and 8oz of Dutch processed cocoa. Before adding the cocoa and lactose to the whirlpool, I checked the wort ph and gravity to make sure I didn't need to boil any further and that I hit my original gravity before cutting the flame. The ph was about 5.2 and the gravity was where it need to be. I cut the flame and added the powders. I took another sample after racking from the kettle to the Fermentor and found my ph has now rose to 5.65! So I added lactic acid until I got it down to 5.35.

So my question, was it the lactose or the Alkine washed cocoa that rose the ph? And is there anything I can do in the future to prevent this rise?

Just curious as it was an interesting event.

Cheers!

 

[ajdelange]

So my question, was it the lactose or the Alkine washed cocoa ...

If that's a misspelling of Alkaline washed I think we have a clue

 

[Colbizle]

If that's a misspelling of Alkaline washed I think we have a clue

Ya thanks aj, I meant "alkaline". So my question is, if I use this cocoa powder again I'll just have to accept having to Acidify the wort to accommodate the rise in ph. Is there any negative impact of doing this? Raising and then acidifying the wort pre-fermentation?

 

[ajdelange]

Ya thanks aj, I meant "alkaline". So my question is, if I use this cocoa powder again I'll just have to accept having to Acidify the wort to accommodate the rise in ph.

Yes. I'd suggest you predetermine how alkaline the cocoa is. Suspend a gram of it in water, measure the pH and titrate to 5.2 with lactic or whatever you fancy. Add that amount of acid scaled by the number of grams added next time you do this beer.

Is there any negative impact of doing this? Raising and then acidifying the wort pre-fermentation?

Well presumably the manufacturer alkaline washed this stuff for some reason. Does cocoa need high pH for some reason? Don't know but what I am thinking of is that acidified alkaline washed cocoa may not be at all what you were hoping for. I guess you could test the 'neutralized' cocoa you experiment with.

As for the beer itself it's the same story as with any other source of alkalinity. If you have to neutralize a mEq you will be adding a mEq of the anion of whatever acid (lactic) you use.

 

[GuldTuborg]

Dutched Cocoa, being washed with potassium carbonate (usually to around neutral pH, I think), is definitely a likely source of pH change in your case. I'd kinda be surprised if 8oz of cocoa raised your pH that much, but I'm no expert on these matters. Cocoa itself is fairly acidic (in the low 5.Xs I think), so it might take a fair amount of Kcarb to bring it back up to neutral. I also haven't a clue what the pH of straight lactose is.

Sorry that's not terribly helpful, but I wanted to at least support your suspicion that the cocoa played a role in this. Next time I'd just get some other form of cocoa, i.e., not Dutched.

 

[Colbizle]

Yes. I'd suggest you predetermine how alkaline the cocoa is. Suspend a gram of it in water, measure the pH and titrate to 5.2 with lactic or whatever you fancy. Add that amount of acid scaled by the number of grams added next time you do this beer.

Well presumably the manufacturer alkaline washed this stuff for some reason. Does cocoa need high pH for some reason? Don't know but what I am thinking of is that acidified alkaline washed cocoa may not be at all what you were hoping for. I guess you could test the 'neutralized' cocoa you experiment with.

As for the beer itself it's the same story as with any other source of alkalinity. If you have to neutralize a mEq you will be adding a mEq of the anion of whatever acid (lactic) you use.

Perfect, this was the exact info I was looking for. Thank you AJ.

 

[ajdelange]

I also haven't a clue what the pH of straight lactose is.

It's not the pH that matters but rather the acidity. I found this in a set of test standards for USP lactose:

"Acidity or alkalinity— Dissolve 6g by heating in 25mLof carbon dioxide-free water,cool,and add 0.3mLof phenolphthalein TS:the solution is colorless,and not more than 0.4mLof 0.1Nsodium hydroxide is required to produce a red color."

This means the P-acidity is less than 0.04*1000/6 = 6.67 mEq/kg. A typical malt might have P acidity of 100 or so.

 

[GuldTuborg]

It's not the pH that matters but rather the acidity. I found this in a set of test standards for USP lactose:

Yes, of course you're correct. I wasn't thinking it through fully. Was just thinking if the pH was close to the finished beer, or lower, we could easily rule this out as a culprit. But, even that might not be true in all cases.