Experiment tying some threads together

[system]

And, back to the very beginning, I’d still like to know just how much calcium BTB chelates.

Okay.

First, my opinion:

I see no theoretical or empirical evidence that gallotannins chelate non-metallic cations any appreciable amount. In fact, I haven’t seen anything that says it does at all. That is not a slag on Martin or his experience, just merely my observation.

With that said, here is the development of this topic in retrospect as I see it:

It seems to have started here:

https://www.homebrewersassociation.org/forum/index.php?topic=31388.msg408921#msg408921

where Martin says the following:

@mabrungard

Brewtan B is a gallotannin that does chelate cations from water. As frequently mentioned in research, Brewtan B does remove iron and copper cations from the water, which helps avoid Fenton reactions. However, calcium and magnesium are also cations that succumb to the gallotannin’s effects. You can expect a small reduction in concentrations of these ions with Brewtan B usage.

@mabrungard

EDIT I’m also guessing if we needed to be aware of any effect on Ca, the makers of BTB would put it in the technical information they put out. I find nothing.

The makers have not, but there are other sources of gallotannin. I don’t recall where I saw it, but there is a journal article somewhere that told of calcium drop with gallotannin use. I recall that the level was in the 10 to 20 ppm range. Not enough to really be concerned with. In addition, yeast do not need ANY calcium in the water for them to function well enough. The only concern would be a slowing in the flocculation and clearing of the beer.

Also, we have it said here, although i think this is just piggybacking off the previous assertion:

https://www.homebrewersassociation.org/forum/index.php?topic=31213.msg406205#msg406205

@mabrungard

Gallotannins are known to chelate any free divalent metals in the wort, including Ca and Mg. I’ve seen research articles that showed something like 20 ppm Ca reduction. I suppose that we should be considering this effect when using gallotannin products.

Now for an assumption: I think Martin may have read the same De Rouck, Et al. piece that we have tossed arround the past 24 hours, in which they say the following:

http://www.lowoxygenbrewing.com/wp-content/uploads/2017/02/Officiele_tekst_voor_Brewing_Science.pdf

“All beers were brewed with 9.56 kg of dry coarse (two-roller) milled pilsner malt (Bavaria Malt, The Netherlands) and 36 litre of reverse osmosis water with addition of 40 ppm Ca2+ for the reference beer and 60 ppm Ca2+ for the beer stabilised with gallotannins. It proved important to add extra calcium at mashing-in in order to compensate for the expected chelating effect of gallotannins [28].”

So my inquisitive spirit led me to search out the reference made:

[quote]…chelating effect of gallotannins [28][/i][/b]."

[/quote]

(On the Mechanisms of Adsorbent Interactions with Haze-Active Protiens and Polyphenols)

and I reached out to Karl Siebert, Professor Emeritus in the Food Science Program at Cornell and former Director of Research at Stroh, who wrote the referenced article:

https://drive.google.com/open?id=0B8F3C1boHghNZl9PVEtwR0kzY0NtQTNfSHFlS1Zvb3pNcXBn

Professor Siebert did not remember any reference to calcium chelation, nor did I read anywhere in the paper about it, so my opinion would be:

1.) Either De Rouck, Et al. misinterpreted or erroneously referenced Siebert;

OR

2.) They meant to reference something else.

I looked deeper into the references and did not see one that had any mention of calcium chelation.

So my assertion is that if calcium chelation from gallotannins use is actually valid, it is going to be negligible and not as severe as the 20 ppm quoted in the De Rouck paper, i.e. I wouldn’t concern myself with it.

EDIT: Of course, as Bryan pointed out before, there needn’t be any guess work here. Prepare two test mashes, one with gallotannins and one without, while holding Ca constant, and send them for analysis.