help with TA Titration

[shoebiedoo]

I have a batch of Pilot Nior juice brewing from Podi Gold and am trying to get my TA measured with a quirky Vinmetrica SC-300

I am able to get a "GOOD CALC" using the 7.0 fluid but when I try with the 4.0 fluid it just floats around 4.47 to 4.5 never indication a good or bad calc. so here's my assumptions and tell me if I'm off base.

I did a TA tritation and figure I'm at 7.2 (although a tad high) is an acceptable measurement. my pH reading of 4.2 is not accurate at all base on my inability to properly calculate pH. Even if I calibrated in my head and subtracted .48 I'm still conflicting with the TA reading. Am I right in saying that I should expect a much lower pH with a TA of 7.2? do I ignore all readings?
or

Should I wait and get a cheap kit until I can get my Vinmetrica unit working?

 

[novalou]

I have a batch of Pilot Nior juice brewing from Podi Gold and am trying to get my TA measured with a quirky Vinmetrica SC-300 I am able to get a "GOOD CALC" using the 7.0 fluid but when I try with the 4.0 fluid it just floats around 4.47 to 4.5 never indication a good or bad calc. so here's my assumptions and tell me if I'm off base. I did a TA tritation and figure I'm at 7.2 (although a tad high) is an acceptable measurement. my pH reading of 4.2 is not accurate at all base on my inability to properly calculate pH. Even if I calibrated in my head and subtracted .48 I'm still conflicting with the TA reading. Am I right in saying that I should expect a much lower pH with a TA of 7.2? do I ignore all readings? or Should I wait and get a cheap kit until I can get my Vinmetrica unit working?

Ignore your pH reading for now and use your TA. It's close enough that I'd let it ferment out and see how it tastes. Do your adjustment after fermentation.

PH and TA don't always agree. For taste, you want to pay attention to TA. You'll want the pH reading for accurate SO2 additions.

 

[GreginND]

But, he's trying to use a pH meter for the endpoint of his TA titration. If the meter isn't working properly the TA value will not be correct.

I would soak your probe in the pH 4 buffer solution for an hour or so. Then try to recalibrate the meter. If it still does not calibrate properly you should look into replacing the probe. Oh, make sure you get some fresh buffer solutions. If they are old they could have evaporated some.

 

[shoebiedoo]

But, he's trying to use a pH meter for the endpoint of his TA titration. If the meter isn't working properly the TA value will not be correct.

I would soak your probe in the pH 4 buffer solution for an hour or so. Then try to recalibrate the meter. If it still does not calibrate properly you should look into replacing the probe. Oh, make sure you get some fresh buffer solutions. If they are old they could have evaporated some.

So even if the pH mater calibrates at 7.0 the end point will still be inaccurate due to the starting point being off? This is a faily new probe and I've had issues from day 1 We're still trying to sort everything out but for now I'm just trying to make sure this batch is OK.

 

[Poni]

I would contact vinmetrica, they are great with custmer service. What is the temperature of your calibration solution? You want it closer to 77°F

 

[GreginND]

I am not sure. If it doesn't calibrate properly it may or may not be accurate at higher pH.

 

[Julie]

Since you can not get a calculation with the 4.0, I would say you just do not have any good numbers and you can't back into them. In the meantime can you go out and get a titration kit? And call vinmetrica's customer service.

 

[GreginND]

Well, it sounds like you have all the things you need for a titration but the ability to measure it. You don't need a whole kit if you can just find some phenolphthalein indicator. I would dilute your samples with distilled water to make it easier to see the endpoint. The red grapes tend to turn blue/green then obscuring the endpoint. It's harder without a pH meter.

 

[thesnow]

Make sure your probe is plugged in well., unplugged your probe and reinstall it well in the socket.