Sulfite Testing Strips Do You Really Need to Adjust pH?


There are a lot of people using sulfite testing strips now and I get a lot of people asking me about needing to adjust pH for these strips to be accurate. I have always adjusted, and never gave it any thought. But it piqued my interest enough to start to take dual readings while brewing. Over 5 batches I took back to back readings while adjusting,  and not adjusting, the samples. These days I find I am not consuming much of the sulfite dose anymore, but for the pictures I chose a dose where you could see some significance. 20ppm sulfites were added in the form of Antioxin SBT.

The mash used for the pictures is as follows:

A quite intensive mash schedule, but also a good test to see how effective my mash protection is.

Water was boiled then cooled, upon reaching 200F, the SBT was added. The water was then further chilled to dough in temps (136f). Right before dough in I took my first reading in the HLT.

A is not adjusted, B is adjusted to a pH of 8 in the series of pictures.

I would call that right about 20ppm.

As the strike doughed in, I added 450ml sauergut. Slow underletting was performed and all my vessels, piping, and grist is purged with N2 .

After dough in and stirring, I took a dough in reading.

So far the strips are nearly identical, and I have no discernible loss of sulfites from from chilling to mash in, SCORE!

The long intensive mash was completed and mash out readings were taken.

(I apologize that A and B got switched here, B(adjusted) is now on the left in this picture.)

You can see there is starting to be a color differentiation between adjusted and non-adjusted. Non-adjusted is measuring higher.

I then took a reading from preboil, which shows me how well I did at lautering. The BK is purged with N2, underlet gently, and once the wort is above the element it is capped with a floating lid.

Here are the readings

Again nearly identical.

The boil then was completed as normal, however I do a trub separation, so my sample post boil was taken AFTER that process was completed. Again this is under a floating lid.

Here are those readings:

We here at LOB already knew this but not all sulfites are evaporated by the boil alone. The wort was then oxygenated to 8ppm and one last reading was taken.

(A)

(B)

 

So what are the take aways?

Well when they started out they were nearly identical, after mash out for some reason the non-adjusted sample jumped up about 25ppm, which I saw in all instances but then it seemed to linearly follow and fall when the adjusted sample did. I don’t recommend using these strips without adjusting, but it was a interesting that in 5 data sets it matched pretty close to that. So do with that what you would like!

A note regarding the proper dose of sulfites. It’s really important! As you can see boiling alone does not remove all the sulfites, excess sulfites after boil will lead to issues with oxygenation. Most folks are not going to have a DO meter so if you are just splashing or going by guesstimate you will have to exhaust the sulfites before the oxygen will actually take hold in the wort. This will also lead to free sulfates in the wort, allowing those yeast to uptake immediately. You will probably see issues with low attenuation (undershooting your o2), and possibly excess sulfur (all yeast handle this differently). Just something to keep in mind as I see a lot of new low oxygen brewers struggle here. Don’t worry we will have a post that goes into to this in much more detail!

Other interesting notes is that after much refinement in processes and system, I am down to not needing sulfites anymore! My normal mashes now a days are sub 10ppm and its mainly there as very cheap insurance!