Why are you using a DO meter

[lupulus]

Hi all,
Just got the new copy of the Narziss summary brewing book (Abriss... 2017). I have borrowed the book before but this is the first copy I own.
To my point...
In 2.3.1.8, in the Oxygen and Mashing section, Narziss repeats the common advice that DO meters do not work in the mash because of the many REDOX reactions occurring (Bamforth has said the same thing -do not recall where-), but adds advice that I have not seen before in the literature. Narziss states
to use sulfites to measure the tightness of your process, a good process will use 30-40mg/L sulfites whereas a bad one can use up to 200mg/L.

My questions:
Many of you have more experiene than I do and you are probably aware of this, so if you are using a DO meter, why?
I have seen measurements published in this forum, but only with the strips, which specifically state in their instructions not to use when other reducing agents are present (my read is that they are not valid in a mash either).
Have anyone use a sulfite kit with other method? Hanna HI3822 as an example...

Thanks in advance,

[Brandon]

Interesting...I have always found it to be flaky with bizarre readings (swapped out parts with the manufacturer, bubbles in the membrane...dammit...etc). I used it mostly during the pre-boil to verify that O2 levels were dropping. After that, it's always been flaky (probably threads on here or FB about it). I'm curious to hear other's experience. This could explain a lot.

[Brandon]

[lupulus]

Thanks Brandon. I saw the experiments and the photos. Extremely interesting. I did comment on the experiments back in December.
All the best!

[Weizenberg]

I initially recommended a DO meter to our little working group, namely the Extech -- witch I've been very happy with for years.

However, this was in the context of aerating wort correctly. I had no idea we ended up sticking it in the mash.

Although the meter did not give an accurate enough reading for definitive conclusions, it was however indicative enough to compare with previous relative ballparks.

There exist optical DO meters. They may not be used in the mashing process, but breweries do have them inline for quality control.

[Owenbräu]

The DO meter allows you a static measure of DO, whereas sulfites give you a relative measure of oxygen uptake in the mash. Relative in that you only know how much oxygen interacted with sulfites, not other mash compounds. So, unless a brewer is willing to develop an integrated model of oxygen uptake based on continuous oxygen measurements, sulfites would be much simpler and provide more meaningful data relative to the mash.

Sulfite tests are pH corrected. If you take a reading with the strips with high sulfite levels and leave it sit out, then oxygen in the atmosphere will eventually consume all of the sulfites and turn the strip white. There is no doubt the reactions are dynamic and continuous, but the static datapoint you collect is relative, accurate and helpful in guiding you to eliminating the 'leaks' in your system.

Point being, even relative measurements demonstrate that you are successfully mitigating oxygen introduction into your system. As long as your readings keep going down, then you are taking the right precautions.

[lindh]

I just bought the Milwakuee DO meter and it only measures up to 30c so I will not stick it directly in the mash. And also for an accurate reading, you're supposed to keep the liquid in motion. I'm not sure how to utilize the DO meter yet but curios to be able to see where in my process oxygen is induced, even if the reading is not accurate it will still indicate potential problems.

[lupulus]

Thanks everyone for taking time to respond.
Abbey, I asked you in the sulfite strip test thread if what can be seen in the picture was correct in that about 50-75ppm sulfite were consumed at mash-in (that is what I interpret from the picture), and if Yes, I would like to add the question of whether that is the normal experience of the group, ie 50-75ppm sulfite consumed at mash-in as per the strips.
Cheers,

[Owenbräu]

The control strip looks to me to be in between 50 and 100 mg/l, which 76 mg/l is expected from 100 mg of SMB. The measurement after doughin in looks in between 25-50 mg/l. I tried to lay the strip on the color if it was dead on, and in the gap if I though it was between readings. That reading could have been as low as 25 mg/l and as high as 50 mg/l. Again, these are all relative measurements to determine if changes we make are causing the relative numbers to go up or down. There is no way to know an exact value from the strips, however, I think we are definitely in the low range, consistent with what you described above from Narziss.

[lupulus]