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Author Topic: Mash ph  (Read 1565 times)

Offline trapae

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Mash ph
« on: May 29, 2014, 04:59:53 pm »
So this is kind of a continuation of my prior thin mash question. I ended up mashing in about 3 quarts per pound of grain.  When I took a pH of the mash it was about 6.1. I added some gypsum, but it didn't help. I went ahead and did the mash for one hour.  After the mash the pH was still around 6.1.  I  got the appropriate pre-boil volume after mash and batch sparge.  I was worried that the conversion would be poor due to pH however I got very close to both my pre-and post boil gravity.  So I'm wondering if everything will be okay or if I am going to have some funky off flavors from the pH.  Any opinions?
By the way, the reason for the thin mass is because the recipe calls for 2 pounds of honey in the last five minutes.

Thanks
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Offline mabrungard

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Re: Mash ph
« Reply #1 on: May 29, 2014, 05:49:59 pm »
Yes, you found out the hard way.

This problem can be summarized by considering that a quantity of malt has a quantity of 'acidity' and it has the ability to neutralize a quantity of alkalinity. The balance of quantity of acidity to the quantity of alkalinity is what drives pH.

Malt has a unit acidity that can be expressed in terms of acidity per kilogram of malt. Since you probably include only a certain amount of grain to reach a desired wort gravity, you can see that you just multiply that acidity per kilogram unit acidity by the total mass of the grist and you end up with a quantity of acidity.

In the case of water, alkalinity is expressed in units of mg/Liter or ppm. To figure out the quantity of alkalinity, you need to multiply that mg/L alkalinity value by the numbers of liters of water in your mash. As you will immediately recognize, the more water you add to a fixed quantity of malt means that you will end up with a larger quantity of alkalinity. That larger quantity of alkalinity ends up overwhelming the fixed amount of acidity and the pH rises. So in this case, the extra thin mash made the pH worse than it would have been with a thicker mash. In fact, a brewer MIGHT be able to achieve a better (lower) pH if they mash thicker.

At a pH of 6.1, the wort probably was impacted by tannins and silicates that were extracted from the grain and into the wort. That is not desirable.

In most cases, even when using low alkalinity water like RO or distilled water, a brewer HAS TO add some form of extra acid to pale grists in order to keep the mash pH low. For example, regular 2-row pale malt mashed with distilled water will produce a mash pH of about 5.7 to 5.8.  That is too high for brewing. That external acid is a necessary fact of brewing. Get used to and familiar with using the various forms of acidification to reduce pH into desirable ranges. I suggest that anyone interested in understanding these factors more thoroughly, please visit the Water Knowledge page of the Bru'n Water website. 

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Offline trapae

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Re: Mash ph
« Reply #2 on: May 29, 2014, 06:04:43 pm »
Is it even worth fermenting the wort?
I am a great believer in luck, and I find the harder I work, the more I have of it.

Offline erockrph

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Re: Mash ph
« Reply #3 on: May 29, 2014, 06:32:25 pm »
Is it even worth fermenting the wort?

If you're into sours this would probably be a decent wort to pitch some sour dregs into. Otherwise, it probably won't be the best beer, but if you have a packet of dry yeast to spare and don't need the fermenter space, then there's no real reason not to try it. You've gone this far, might as well let treat it like an experiment and learn what happens.
Eric B.

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Offline trapae

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Re: Mash ph
« Reply #4 on: May 29, 2014, 07:54:34 pm »
Down the drain.  I tasted the wort and it was astringent and mouth puckering.  Oh we'll, won't do that again.
Thanks for the help.
I am a great believer in luck, and I find the harder I work, the more I have of it.