Why not sodium bisulphate?

[Swarbs]

hey all,
I have a Question on why I can’t find any info on using sodium bisulphate to lower the PH in mash water. I can find articles on food preparation and wine making and even pool water adjustment (not food grade) but nothing on beer brewing. I have read that it can be used as a preservative does this effect the yeast even with the small amounts needed to lower PH from 7.8 - 5.2. Any info would be much appreciated before I give it a test run

 

[ajdelange]

I have a Question on why I can’t find any info on using sodium bisulphate to lower the PH in mash water.

Are you sure you mean bisulfate and not bisulfite?

The former is rarely used in brewing because it is just sulfuric acid with half the available protons per mole. If you want pH reduction and can tolerate sulfate then most brewers would use sulfuric acid and get twice as much acidity per mmol of introduced sulfate.

OTOH bisulFITE and metabisulFITE are frequently used to remove chlorine and chloramine from water.

Reassure me that you mean bisulFATE and I'll post more on how it can be used.

 

[Swarbs]

Hi ajdelange,

It was defiantly bisulphate, I have attached a pic of the pool water container that made me curious. I was told it was taste less, odour less and a less aggressive acid than citric as a food grade product.

 

[ESBrewer]

I think adding phosphoric acid will be simpler in most cases cause you will get the low pH value without sodium, which is usually an unwanted addition (although some beers could benefit from a small sodium addition). In addition, CaSO4 can give the sulphate AND lower the pH during the mash without the unwanted sodium. It also brings calcium up which is often useful for the yeast, precipitation etc. And if you have already hit a certain water profile and then need to adjust mash pH (during the mash process) you typically want to keep additional ions in minimum so phosphoric acid would be more effective and suitable than sodium bisulphate, that has weaker effect on pH and adds sodium, too.

 

[dmtaylor]

I think adding phosphoric acid will be simpler in most cases cause you will get the low pH value without sodium, which is usually an unwanted addition (although some beers could benefit from a small sodium addition). In addition, CaSO4 can give the sulphate AND lower the pH during the mash without the unwanted sodium. It also brings calcium up which is often useful for the yeast, precipitation etc. And if you have already hit a certain water profile and then need to adjust mash pH (during the mash process) you typically want to keep additional ions in minimum so phosphoric acid would be more effective and suitable than sodium bisulphate, that has weaker effect on pH and adds sodium, too.

I agree with this. You can use sodium bisulphate.... but I might reserve its use for gose or a style where high sodium is expected. Then taste to see if you need to reduce sodium chloride (table salt) addition accordingly.

 

[ajdelange]

OK then. Sodium bisulfate is sort of "once used" sulfuric acid. When you add sulfuric acid to a mixture at mash pH it gives uo 2 protons:

H2SO4 ---> 2H+ + SO4--

With sodium bisulfate one has already been given up and replaced by sodium so the reaction is

NaHSO4 ---> H+ + SO4--

When calculating mash pH one determines how many milliequivlents of acid one needs and divides by the number of protons one mmol of the particular acid at hand releases. That gives the number of mmol of that acid needed. For example, if you determine that 40 mEq of protons are needed and you have lactic acid which releases 0.972 protons molecule you would need 40/0.972 mmol of lactic acid. In the case of sulfuric acid which releases 2 protons per molecule you would need 40/2 mmol and, for sodium bisulfate which releases 1 you would need 40/1 mmol.

Next we consider the molecular weight of sodium bisulfate. It is 120.06 mg/mmol for the anhydride and 138.07 for the monohydrate (NaHSO4.H2O). Thus for 40 mEq of protons you would need 120.06*40/1 milligrams or 4.8 grams.

You probably will not find a calculator that will do these calculations for you so find one that tells you how much 88% lactic acid you need. Most of these programs think that 88% lactic acid delivers 11.77 mEq protons per mL. It's really 11.44 (to pH 5.4) but assume that your program is using 11.77. Each mL of lactic acid is thus equivalent to (11.77/1)*120.06 = 1413.11 mg of NaHSO4.0H2O. NaHSO4 releases 1 mmol sodium and 1 mmol of SO4 for each mEq of protons. Thus each mL of 88% lactic acid if it be replaced by the equivalent amount of NaHSO4 will put 11.77 mmol of sodium (270 mg) and 11.77 mmol of SO4-- (1129.92 mg) into your brew. To put this in perspective 5 gallons of 12 °P pilsner with a typical grain bill might require about 1.4 mL of 88% lactic acid and thus load your beer with 378 mg sodium if NaHSO4 be used instead. That may seem a lot but is 20 mg/L over the 5 gallons. Similarly you will have 1581.89 mg sulfate equivalent to 83.6 mg/L in the finished beer. Note that were you to use sulfuric acid to replace the lactic you would have half the sulfate and no sodium.

Sodium bisulfate (in food grade) is considered GRAS. Thus it is safe to handle and that's, no doubt, why it is used in pools in preference to H2SO4. When I was a kid children were allowed to have chemistry sets (OMIGOD - call Home Land Security, Child Welfare, the Nation Guard and CNN!) and, as the most commonly used chemical is sulfuric acid, the manufacturers of these sets needed to put sulfuric acid in them somehow. They didn't of course. Even in those terrible, terrible times they didn't give fuming H2SO4 to children. They used NaHSO4 and were able to demonstrate lots of acid/base reactions with it.

Many of the questions about water treatment here are from brewers wanting to make an ale using alkaline water poor (relative to the insane levels some ale drinkers like) in sulfate. I often bemoan that AMS/CRS (a mixture of sulfuric and hydrochloric acids sold in the UK) isn't available in the US as it simultaneously removes alkalinity and boosts sulfate. From the discussion here it is clear that NaHSO4 is an alternative if one can live with the sodium. Is it more readily available? A quick search turned up a 55 pound bag of food grade for $175 so its relatively cheap if you can get it in reasonable quantity (or have a lot of brewing friends).

 

[ajdelange]

The more I think about it the better I like the idea of using sodium bisulfate. I think I shall refer to its use as the Half Acid approach to alkalinity neutralization.

 

[Silver_Is_Money]

The more I think about it the better I like the idea of using sodium bisulfate. I think I shall refer to its use as the Half Acid approach to alkalinity neutralization.

You haven't lost your humor!

 

[ScrewyBrewer]

I used to be fast now I’m only half fast.