Dissolving gypsum.

I've been messing about with gypsum additions to emulate the beer I grew up with - Marston's Pedigree. With some success too, but I'm running into problems that could be putting me off trying further experiments.

At the moment I'm getting about 230ppm sulphate into my water in the form of gypsum, and another 70ppm as Epsom salts. This has a marked effect on the flavour (malt flavours, I don't really notice the reputed effects on hop bitterness). The flavour is instantly recognisable as Pedigree. I'm about at maximum for dissolving gypsum (only about 0.5g/L), it's quite a process, involving putting the gypsum in a litre of water (about 25g), using a stick blender on it for about 1 minute, settling for 2-3 minutes, returning the clear (-ish) portion back to the 60L of brewing water, recharging the flask with another litre, and repeating several times (5-6?) until the gypsum is mainly dissolved.

The problems are:

1: It's time consuming! Taking at least an hour (about 60L for sparging, but another 20 for mashing).

2: I'm getting about 230ppm sulphate dissolved, but Burton water is reputed to have 600-800ppm. About 1/4 can be attributed to Epsom Salt but that's easy to dissolve.

3: While the effect on the flavour is definitely going the right way, those effects are not as strong as the real thing (hardly surprising, I'm not getting so much gypsum dissolved).

4: THE BIG ONE! The flavour enhancement is temporary. From tapping the barrel (at this point only about two weeks from starting brew) there is only three weeks before the flavour effect evaporates. It then becomes an "average" beer. As my smallest brew length is 40L this means there is still an entire keg unbroached.

The beer is served with minimal carbonation (equivalent to 1-2psi), from hand pump and at about 14-5degrees. I am very aware that serving chilled and at high carbonation will kill such subtle effects.

SO... Has anyone got a tried and tested method for dissolving large quantities of gypsum? Some 1-2g/L? I understand that gypsum dissolves best at 40degrees (NOT boiling) and will try that next (I've been trying at 15-20degrees). Has anyone effectively dealt with similar problems with gypsum, especially the "only temporary" one?

Cheers

[Dennis King]

I only use small amounts that are split 50/50 in the mash and boil. The mash salts I add to the grain. With the boil I put some first runnings in a jug add the salts and stir like made for several mins. before adding to the boil.

Just because profiles are quoted with that level of sulphate in doesn't mean the brewers used it!!, Indeed I've seen books that suggest the maximum level that brewers used would have been about 350mg/l

In cold(20C),distilled, water gypsum will dissolve at a maximum of 2750mg/l, warming it doesn't help as it is less soluble in hot water . . . even 40C is going to have a detrimental effect.

I'll be quite frank, I treat the full volume of the water, the night before, and have no issues getting 350-400mg/l sulphate from gypsum . . . but, here is the rub, I have practically nothing in the water, if you have medium to high levels of calcium, or are using calcium chloride, as well, then you are going to have the devils own job to get it to dissolve, and trying to get it to happen in a small volume of liquor is making it even harder.

The way I've seen brewing salts used in a commercial setting is to mix them in with the grains when you mash in. That's the same thing that Murphys told me to do when I got my water report from them with their recommendations for brewing salt additions.

I don't treat my sparge water other than half a campden tablet, as all the salts are in the mash from the start.

Maybe AMS would work better for you if soluability is a problem and you're concerned about having no salts left in the mash at the sparge stage... http://www.murphyandson.co.uk/Datasheets/AMS.pdf

Before this thread runs off in a direction I wasn't planning...

I do not have a particular problem with pH at any stage, which I guess is down to adequate water treatment. I started this thread solely to figure out a good way of adding large amounts of gypsum so it can more directly influence the flavour of the beer; because gypsum will "taste" and modify the taste (and aroma, as in the famous Burton "snatch"). And perhaps figure out how to make those changes to flavour a lot less transient (at the moment I only get the desired flavour enhancements for about three weeks).

What I've gleaned so far is to attempt dissolving the gypsum first, before any attempt to dissolve the easier stuff (especially <other> calcium salts), and warm the water only very slightly before attempting to dissolve gypsum (between 25C and 40C, say 30C?).

(EDIT: 22/01 19:10 inserted "<other>" for clarity, in reaction to following post).

Gypsum is a calcium salt, calcium sulphate dihydrate, CaSO4. 2H2O.

Maybe my water is conducive, but it only takes a bit of stirring (manually, with a big spoon) to dissolve quite a lot of gypsum in the full volume of (tepid) mash water. Its a little stubborn certainly, but nothing hugely taxing. I usually add the gypsum before other salts mainly because it takes longer to dissolve; perhaps this order is a happy accident.

Personal preferences vary; I just like to dissolve my salts in clean liquor in order to visually check that they have dissolved properly, and its also easier to stir/mix to uniformity before the grain is introduced. But its not the only method.

Eric's point about not neglecting the sparge liquor (If I understood correctly) makes sense to me too, if the water is lacking. We know that pH is important in the sparge (as well as the mash) so salts diminishing too far during that stage would be detrimental. I'm also coming to the conclusion that decent calcium levels in all mash/sparge/boil stages is no bad thing.

Damn it, this forum doesn't change!
Nit picking to the Nth degree about Gypsum and Epsom...I despair.
Come on chaps, brewing is an art, not a science!

I await the flak
Jim

I'd say it's a balance of art AND science. You can take the arty approach and you'll eventually find your way by trial and error. Alternatively, you can fully understand the science behind things and use that to your advantage.

The 600 to 800 ppm sulfate reputed for Burton water is from local groundwater results. However, the local hydrology and aquifers led to significant dilution of those concentrations at the breweries. Sulfate-rich water permeates up through the local marl into the shallow sand and gravel aquifer. That shallow aquifer is directly connected to River Trent, whose waters are much less mineralized. When there is little groundwater withdrawal from the shallow aquifer, that water might have been as high as reputed. The preponderance of breweries in Burton meant that there was a lot of withdrawal at one time. Many of those breweries drilled wells directly into the deep aquifer below the marl to get more mineralized water, but they did have to dilute it with the shallow water to make it suitable for brewing.

600 to 800 ppm sulfate is not a goal you should seek in brewing, but I do suggest that you try adding an appropriate slug of gypsum to a glass of your beer to replicate that level. See if you like it. Most have found that it's not ideal.

Colin Kaminski (co-author of the Water book) told me that he brewed some pale ales at his brewery in Napa California with 600 ppm sulfate. He said he liked the beers, but most of his customers did not.

[GrowlingDog]