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I recently moved and my water here is quite soft with a very low pH. As such, I've taken to adding many of my brewing salts in the brew kettle and only using salts in the mash to balance the pH.

However, with a very low pH in the water to begin with, brewing a very dark beer means I'm going to leave as much calcium out of the mash as possible (because calcium lowers the pH). I do add some because I raise the pH with a combination of Sodium Bicarbonate and Calcium Carbonate.

I know calcium is vital for efficiency and is supposed to help stablize alpha-amylase, so I was wondering what ppm I should be after with Calcium in the mash to ensure the best efficiency and alpha-amylase stability.

My guess is 50 ppm, but I'm hoping someone out there has a legit answer. Thanks!

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I think you're on the mark. a minimum of 50ppm is considered beneficial, while some water sources have in excess of 250ppm with no problems, such as Burton (295ppm) and Vienna (250ppm) water. But since you want to reduce the amount of pH reduction, your plan to add only 50ppm in the mash and put the rest in the boil is a good one.

Calcium plays a role in many areas - the mash, in sparge water and in the boil, and in the fermentor, so as long as some of your calcium gets to reach all these areas, then I think you're ok.

Beer Brewing, The Art and Science, lists beer styles ranging from 50-200 ppm in calcium. It also describes how calcium is used from the mash through to packaging:

Of the ions required for brewing, calcium is by far the most important. This is because of the acidifying effect that calcium has on the wort. [...] A combination of the presence of calcium ions and the decrease in pH has a number of effects on the brewing process:

  • The lower pH improves ß-amylase activity and thus wort fermentability and extract. The optimum pH for ß-amylase activity is about 4·7. Wort produced from liquor containing no calcium has a pH in the order of 5·8 - 6·0, compared to values in the range of 5·3 - 5·5 for worts produced from treated brewing liquor. The activity of the ß-amylase then is greatly enhanced by the addition of calcium, this enzyme increasing the production of maltose from Amylose, and thus making worts more fermentable.

  • Calcium has a beneficial effect on the precipitation of wort proteins, both during mashing and during the boil.

Protein-H + Ca2+ (r) Protein-Ca ¯ + 2H+

The hydrogen ions released further reduce the pH which encourages further precipitation of proteins.

Proteins are also degraded, that is converted to simpler substances by proteolytic enzymes called proteases. These are found in the malt, and have optimum activity at pH values of about 4·5 - 5·0. The reduction in pH then caused by the presence of calcium encourages proteolysis, further reducing protein levels and increasing wort Free Amino Nitrogen levels (FAN).

FAN compounds are utilised by the yeast during fermentation for the manufacture of amino acids, and an increase in FAN levels in the wort improves the health and vigour of the yeast.

High protein levels in beers also have negative effects, making beer more difficult to fine and encouraging formation of hazes, in particular chill hazes. Product shelf life can also be adversely affected.

  • Calcium ions protect the enzyme a-amylase from inhibition by heat.

a-amylase is an endo enzyme, cleaving the internal 1,4 glucosidic links of amylopectin resulting in a rapid reduction in wort viscosity. The optimum temperature range for

a-amylase activity is 65°C - 68°C, but the enzyme is rapidly destroyed at these temperatures. Calcium stabilises a-amylase to 70 - 75°C.

It can be seen then that the presence of calcium has positive effects on the activity of a-amylase, ß-amylase and Proteases, some of the most important enzymes in the brewing process.

  • The drop in pH encouraged by Calcium ions in the mash and copper helps afford the wort and subsequent beer produced a greater resistance to microbiological infection.

  • The reduced pH of the sparge liquor reduces extraction of undesirable silicates, tannins and polyphenols from the mash bed. The extraction of such materials is encouraged by alkaline sparge liquor. These materials are very undesirable, contributing to harsh flavours, hazes in the finished beer and decreased beer stability.

  • Calcium precipitates oxalates as insoluble calcium oxalate.

This again occurs in both the mash tun and the copper. If oxalates are not removed they can cause hazes in finished beers and also contribute to the formation of beerstone in FV's, CT's and casks. Oxalates are also thought to promote gushing in certain beers, although this is not generally a problem to the micro brewer.

Your low water pH probably means few dissolved solids, particularly (bi)carbonates, which is a great starting point for brewing, as you are now in control over much of the water chemistry, compared to folks with water pH in the 7-8 range with larger amounts of dissolved solids, which can make brewing pale beers tricky.

As well as the points you mention, Calcium is also good for long term colloidal stability, which helps reduce permanent haze.

EDIT: Confirmation of 50ppm

For the best results, your brewing water should have less than 50 ppm carbonates and around 50–75 ppm calcium ions. BYO, american pilsner profile

See

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Great answer, thank you. It's been an adjustment moving to this water supply but I'm finally getting a handle on it. –  Hop the Mad Alchemist Feb 1 '12 at 15:07
    
You're welcome - if you like the answer, please click on the large green check mark to mark this as your accepted answer. –  mdma Feb 8 '12 at 16:37
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Recent research by water engineer Martin Bru'ngard (author of the killer Bru'nwater spreadsheet)is leading to the conclusion that less calcium is needed than previously thought. His preliminary findings are that 50 ppm of Ca is generally enough for ales, and lager yeast may perform better with as little as 20 ppm. Too much Ca can lead to cloudy beers. His findings at this point are preliminary, but point to some interesting information.

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