Ph test

[silverbullet07]

I purchased a PH tester and calibrated it with distilled water and the ph buffer powders. It passes the calibration and then went to test the distilled water. I was expecting a PH 7.0 however it was reading a PH of 5.8. So that worried me and started researching. I found that after a couple hours the distilled water absorbs carbon dioxide which reacts with the water to produce carbonic acid, which in turn releases hydronium ions into solution. After two hours it absorbs all the Carbon Dioxide it can to produce it's final PH which is around 5.8.

Fun to learn something new.

Tested my filtered well water and it's PH is 7.4 . It has a special media filtration that removes iron, sulfur, bacteria, heavy metals. Our water taste really good and do not have any issues with it so I am hoping it will be good to add to our wine.

Getting closer to starting my fist batch.

 

[BMarNJ]

I purchased a PH tester and calibrated it with distilled water and the ph buffer powders. It passes the calibration and then went to test the distilled water. I was expecting a PH 7.0 however it was reading a PH of 5.8. So that worried me and started researching. I found that after a couple hours the distilled water absorbs carbon dioxide which reacts with the water to produce carbonic acid, which in turn releases hydronium ions into solution. After two hours it absorbs all the Carbon Dioxide it can to produce it's final PH which is around 5.8.

Fun to learn something new.

Tested my filtered well water and it's PH is 7.4 . It has a special media filtration that removes iron, sulfur, bacteria, heavy metals. Our water taste really good and do not have any issues with it so I am hoping it will be good to add to our wine.

Getting closer to starting my fist batch.

I was worried about the same thing because my distilled water was not coming in at pH 7.. but my real worry is the test i use from morewine.com for TA. You put 5 ml of wine in a container, top it off with distilled water, then test for TA by adding drops of 0.1N sodium hydroxide until you reach a pH of 8.2 in the solution. Doesn’t the pH of the distilled water affect this test?

 

[silverbullet07]

If that is the test you use with your PH tester, you should not top off your wine with distilled water. You add some drops of 0.1N sodium hydroxide straight to the wine and you keep testing until you reach 8.2. Then use a calculation to determine your TA level.

 

[BMarNJ]

Was thinking that, but the calculation is based on 5ml of wine. I’d need more than that to get the tester wet, so the amount of sodium hydroxide would have to change too. Was thinking that I could use 15ml of wine then divide the amount required for the change by 3 to get the value, you think?

 

[sour_grapes]

Follow the MoreWine instructions. What you are not understanding is that pH is a logarithmic scale. The test is calibrated to titrate the number of ions in 5 mL of wine (i.e., the acid). There are essentially NO ions in the water you add (compared to the number in the wine). So it doesn't really matter whether the pH of the water you add is 5 or 7, nor is the volume of added water that important. The base you add will still have to titrate the same number of ions from the wine.

 

[BMarNJ]

Follow the MoreWine instructions. What you are not understanding is that pH is a logarithmic scale. The test is calibrated to titrate the number of ions in 5 mL of wine (i.e., the acid). There are essentially NO ions in the water you add (compared to the number in the wine). So it doesn't really matter whether the pH of the water you add is 5 or 7, nor is the volume of added water that important. The base you add will still have to titrate the same number of ions from the wine.

Thanks @sour_grapes , thats what I needed to understand. The fact that you use a pH meter to find the endpoint of the test was confusing me. .. and the fact that my TA was pretty low took me down that rabbit hole.

 

[silverbullet07]

Was thinking that, but the calculation is based on 5ml of wine. I’d need more than that to get the tester wet, so the amount of sodium hydroxide would have to change too. Was thinking that I could use 15ml of wine then divide the amount required for the change by 3 to get the value, you think?

Their test most be Little different. I was following this youtube video. He was explaining the process well.

 

[Rice_Guy]

Yes CO2 can change pH , ,,,, HOWEVER ,,,, a system with no salts buffering it will show dramatic swings with little input.

,,, ex.sparkling water. , , , pH With CO2 3.5. pH without CO2 7.2 (a non buffered system consisting of carbonated city water and natural organic flavor)

 

[CDrew]

Diluting the wine with distilled or deionized water just makes the sample easier to handle if you use a stir bar and a lab stand. The reasons it doesn't affect the pH titration is well explained by @sour_grapes . Also the size of the wine sample doesn't really matter either, as long as you know it precisely. The proprietary methods like Vinmetricas, use odd concentrations of the titrant, in order to simplify the math, and make sure you have to buy chemicals from them. But if you are not afraid of multiplication and division, just use standard concentrations and your pH meter. The equation takes into account the amounts of wine and concentrations of your solution. It just so happens that 5-10ml of wine works well with 0.1N NaOH. I load up a 50 ml burette with titrant and can run 4-5 titrations in 10 minutes. It takes longer to set up and clean up.

 

[BMarNJ]

Their test most be Little different. I was following this youtube video. He was explaining the process well.

The test is basically the same but you only use 5 ml of wine and then you don’t need as much sodium hydroxide to achieve the end result. I’d rather add the distilled water and use less NaOH, since its cheaper and easier to come by.

 

[silverbullet07]

Can you post the instructions and the calculation? I would like to give it a try.

 

[BMarNJ]

Can you post the instructions and the calculation? I would like to give it a try.

5ml of the sample wine in 100ml of distilled water. Same 8.2 endpoint, same Sodium Hydroxide 0.1N, just multiply amont used by 1.5.

 

[silverbullet07]

Thanks

 

[AaronSC]

I have the "Vinmetricas" system that, as folks have pointed out, takes the "math" out of the the equation. You use 5ml of wine, diluted, and measure the delta of the Sodium Hydroxide from start to finish and multiple it by 2 (ok, there is some math). They set things up so that the concentration of Sodium Hydroxide they provide allows this to be simple. It also beeps when you reach 8.2

I am thinking of switching to using 15 ml wine samples and standard Sodium Hydroxide 0.1 solution because it's has better resolution. The 5 mL sample saves on Sodium Hydroxide but gives coarser readings, since the impact of each drop is so much more.

I actually don't know how much more accurate this would be, but I think it would be reasonably more accurate. I'm also thinking of weighing the syringe empty, before and after to better calculate the delta, since eye-balling it is very coarse as well.

Am I being a bit crazy here?

 

[Rice_Guy]

The first question is what concentration of sodium hydroxide can you buy?

Can you post the instructions and the calculation? I would like to give it a try.

The version I am running takes 0.2 normal NaOH:
1) measure 15 ml of sample into a test beaker(cup)
2) rinse the pH probe with distilled water, mix the juice with the probe, read the pH when it is stable and record this number as sample pH
3) fill a 10 ml syringe with NaOH and then drop liquid into test juice while swirling
at pH 6 mix till stable, at pH 7.5 change to a add one drop followed by swirl till stable procedure
4) stop when the pH is 8.2 and read the volume of sodium hydroxide
5) wash the head of the probe with distilled water (a sprayer bottle helps)
6) calculation: TA (percentage) equals volume titrant x 0.1
, , or ml volume titrant equals TA as grams per liter
.
Other:
*you need enough liquid to submerge the head of the probe, distilled water is transparent, but don’t use bottled drinking water or steam distilled baby formula water with minerals added
*I will reduce the sample size for high TA materials and then put a multiplier in the formula to correct back to a 15ml sample.
*this procedure is convenient in good part because Wine And Hops sells the chemical, but there is no magic to it, when I was in the QA lab the chemicals would have to be made and then the formula corrected for normality of NaOH, ,,,, ie the first question is what concentration of sodium hydroxide can you buy?
*the main use of the info for me is to build a target TA when formulating a fruit wine using natural food rules, ,,, ie no acid blend from the chemical jar
*most red juices will turn blue at pH 6 which tells you to slow down how fast you add reagent
*with most juices (pH 4 or less) I will add ten drops then mix it in with the probe to speed the titration, for me mixing is a one handed operation and syringe is a one hand operation
*syringes are available at the pharmacy for dosing meds for kids, I currently have 5 ml syringes

 

[Trevisan]

I was planning to bottle my 2019 Amador County Zinfandel. I tested the pH % the reading was 4.18 .
I was 3.71 after fermentation. It has been aging in glass and stainless steel. Has anyone had such a jump in pH? My Vinmetrica calibrated to 4.35 and I am wondering if there is an issue with the probe. I am hesitant to add tartaric acid not knowing if the analysis is correct.

 

[Rice_Guy]

0.6 pH sounds like a big jump, ,,,, from when I have both of the two numbers I would have said 0.2 pH increase, ,,, maybe 0.3 pH . Do you have TA numbers for 2019 (young) and now?

TA came up at the vinters club last week, with the “normal” being that it will decrease due to binding of tannin with acid. There is some work published on potassium tartrate and it dropping out of solution. The change is not consistent, ,,, ie several variables involved in that chemistry.

At this point most of us only change the wine if the flavor need it.

I was planning to bottle my 2019 Amador County Zinfandel. I tested the pH % the reading was 4.18 .
I was 3.71 after fermentation. It has been aging in glass and stainless steel. Has anyone had such a jump in pH? My Vinmetrica calibrated to 4.35 and I am wondering if there is an issue with the probe. I am hesitant to add tartaric acid not knowing if the analysis is correct.

 

[Scooter68]

Remember that until your CO2 gasses off you pH will be lower due to the CO2 Presence. So the reading right after fermentation is skewed by the CO2 so the current reading is more accurate. As Rice_Guy says a big change would be unusual My match says the change is .47 - still a big change. But perhaps your pH reading at one of those points was off due to calibration issues.

 

[user 36973]

My Vinmetrica calibrated to 4.35 and I am wondering if there is an issue with the probe.

Do you have fresh pH standards you can use for the calibration? Your wine being 4.18 is exceptionally and almost unbelievably high. Careful cleaning and storage of the electrode is critical when not in use.

I don't have a vinmetrica, just a lab quality buret and a pH meter. I've seen my electrode drift by up to 0.2 at times, so frequent calibration is necessary for accuracy.

 

[ybl84f1]

Great thread! Touches on everything I was wondering about in the back of my mind about TA testing!

I use the CellarScience Acid Test Kit from Morewine and found 1) continuously adding to the vial, capping it and shaking it was tiresome and 2) I could not detect the color change with reds to any degree of accuracy. Then I remembered I happened to already have this great little stirrer for my pool chemistry (Taylor 9265 Magnetic Stirrer) and combined with the Milwaukee pH Meter testing is now much easier and much more accurate.

The vial that comes with the Taylor stirrer is narrow and tall so its great for small sample sizes that you need to stick a probe into. Also, if you also use the Vinmetrica SC-100A for SO2 measurement, you can use the stirrer with the larger polypropylene beaker that the kit includes by simply manually holding it on top of the stirrer base.

The only other thing I'd add is a comment/reminder about shelf life: On Morewine it says "Sodium Hydroxide Solution - 0.1 Normal (2 year shelf life cool & closed, 3 month shelf life cool and opened)". I'm a newbie wine maker and don't go through an entire container in 3 months so I guess I'll need to replenish it.