Why would anyone want to "guesstimate" their pH? It is easy enough to test if you don't want to use a recipe that has already been tested.

Plus the pH of any water/vinegar solution isn't really the issue. It is the pH of the predominant ingredient that determines the pH of the final mixture be that cucumbers, peppers, peaches, eggs or pigs feet, etc. You have to get their pH below 4.6 and keep it there.

You can safely pickle just about anything in straight 5% vinegar assuming the vinegar amount is proportionate to the primary ingredient amount. How long and how you store it are where the safety issues arise.

Plus vinegar and its pH or the pH of vinegar mixed with water applies only to pickling which is a relatively small part of home food preservation for most of us.

Dave

1. White vinegar can vary from 2.4 to 3.4 pH according to USDA. Cider vinegar can be 3.1. Malt vinegar, rice vinegar, all different pHs/acidity levels.

2. You're assuming perfect 7.0 neutral pH for the water? Most tap water is not neutral - Dave explained that on another thread.

3. How is knowing the pH of (distilled) water mixed with white vinegar of use to the home canner? You're neglecting the pH of the food that you are actually trying to pickle, and unless you're trying to pickle or acidify aloe juice or some other low-acid liquid, the calculations (which you didn't even show) aren't straightforward.

Straight 5% vinegar or at most 1:1 ratio is what has been tested and found to be safe with even slightly alkaline tap water (in the 8's) and low-acid vegetables (up to almost 7 pH).

Again, this has come up on other threads and I don't see why we have to keep rehashing it.

Most people just want a pickle recipe that's safe, they don't want to develop their own and do the testing (including shelf stability) that's required.

This post was edited by ajsmama on Mon, Oct 21, 13 at 22:54

Why would anyone want to "guesstimate" their pH? It is easy enough to test if you don't want to use a recipe that has already been tested.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FIRST OF ALL FACTUAL INFORMATION IS NOT HARMFUL. DO HAVE PROBLEMS WITH INFORMATION?

It is not "EASY ENOUGH" to test and measure pH. First, you have to spend hundreds of dollars for a reliable pH meter and have to be able to calibrate it ... so it is neither EASY nor practicall for everybody.
BUT
If You have other sources and ways to do just that. Nobody is forcing you to do anything. What I presented is very basic fundamentals about attaining a pH level., when and if applicable.

FIRST OF ALL FACTUAL INFORMATION IS NOT HARMFUL. DO HAVE PROBLEMS WITH INFORMATION?

Not at all. When it is actually factual. But a list of supposed pHs based on unknown calculations of a mix of vinegar and water when the actual pH of the water is unknown and the actual pH of the vinegar is unknown isn't factual information. Plus it isn't applicable to food preservation when the pH of the food being preserved isn't even taken into consideration..

As Sheila already pointed out the pH of various brands and types of vinegar varies and the pH of residential tap water varies from city to city and state to state throughout the US. EPA standards recommended range for pH in drinking water of 6.5 to 8.5 and many large cities use 7.5 to 8.5 to control the precipitate in their public supply systems. You can go to the Washington State Dept. of Health website and see what CCR reports on water analysis for the past 3 years and learn that it alone has a wide range of variance depending on the primary source. This not to mention all those who live on well water or use water softening systems.

And it is easy to test your pH by just using litmus paper - cheap and easy to get at any drug store. It's not recommended to do so but is approved by the FDA for those doing commercial food sales.

You are free to use your computations of course but they are not be applicable to others and could easily be misleading to some.

Dave

But it's of no practical use to know what the pH of your brine is, unless you say have a recipe that's approved, know the pH of that brine (let's say 2.5), and either don't have 5% vinegar or have very alkaline water (I looked it up which is why Dave beat me to the punch, federal guidelines say 6.5 to 8.5 for city water - and well water probably falls within that wide range too). So if you wanted to calculate how much of your 4% vinegar (which Linda Ziedrich did on her blog) to use instead of 5%, or how much more 5% vinegar to use with your 8.5 pH water to be really safe (assuming the recipe was tested with something lower - but most likely not, since most municipalities try to keep it around 8.1), you could do it.

But you need to know what the pH of the tested brine was, and also how to do the calculations - for a weak acid such as acetic acid, it's a quadratic equation. I don't know about the rest of you (and seysonn, I have not checked your math), but I'm a little rusty, I don't think I've solved one of those in about 20 years.

So this is an interesting discussion if you're into that sort of thing, but really of no practical use in home canning. If I were making up my own recipes (and maybe even if I don't ever do that, if I want to sell pickles in this state I may have to measure the pH of each batch), I think I'd rather buy a pH meter and the buffering solution (and I'm sure the state won't go on calculations anyway).

Fine. As I said nobody is forcing you to use it:

1- 5% acidity vinegar has always has 5% acetic acid. Regardless it is distilled, cider or wine vinegar. It can NEVER HAV A pH OF 3.4. Even IFF a vinegar has 2.5% acetic acid, it will have a pH =2.56

2 - in the calculations we have assume pure water with pH =7(neutral). Therefore dilutinh with acidic city water (pH less than 7)any deviation from that will have negligible effect. It is true that the pH of municipal waters vary between 6 and 8. But its effects in diluting vinegar negligible. MOST MUNICIPALITIES TRY TO KEEP AT NEUTRAL(ph=7), if economically feasible. That is the ideal(NEUTRAL) to prevent corrosion and deposits.

But that is not the issue here.

3- If you have any evidence and proof that what I have stated is INCORRECT, present YOUR correct numbers Then I will apologize to everyone here. Actually in my post asked you to correct me if I am wrong.

4- I have not given any recipe' or an instruction how to can and what to can. I have just presented pH of household vinegar at various dilutions. SO WE ARE NOT TALKING ABOUT RECIPE'S HERE.

5- It is fine. You CAN use litmus paper, pH meter or any other methods.

5% acidity vinegar is 50g/L divided by 60 g/mol = 0.833 initial concentration. Ignoring the dissociation of the acid since acetic acid is a weak acid, so we don't have to solve the quadratic, we can just say pH = -log [square root (Ka*0.833)]

Since Ka for acetic acid is 1.8x10^-5, pH (quick and dirty) is
-log [sqrt (1.5x10^-5)] = 2.41 - you are correct.

diliuted by half with distilled water (perfect 7.0 pH) gives 2.5% acidity, half the concentration, so pH = -log[sqrt(7.5x10^-6)] = 2.56 OK

Diluted by 1/3 (2/3 distilled water, 1/3 5% vinegar) the acidity drops to 1/3 the concentration or 1.6667% acidity or 0.2778 concentration so pH = -log [sqrt(1.8x10^-5*0.2778)] or 2.65 - check.

So yes, your calculations appear to be correct using the simplified equation for a weak aqueous solution but again of what use is this to the home canner? If you did not intend this to be used as a "recipe" or guideline for pickling, what was your intent in posting it to this forum?

Edited to correct calculations for molecular weight of 60 rather than 57 initially used.

This post was edited by ajsmama on Mon, Oct 21, 13 at 23:02

I think this MIGHT be handy, if you don't have an approved recipe or are trying something totally new. MOST home canners don't do this. If someone wants to be their own chemist, this would be helpful, but that's not me.

It is trivia, just like we love to watch on Jeopardy.

I think it's interesting and informative, thanks seysonn, I'm impressed.

Thanks Sid , myfamily ...

ajsmama .... First you have one mistake and that is the molar weight of acetic acid : IT IS 60 INSTEAD OF 57. that is the reason for small difference between your and my numbers.

WHAT IS ITS US? it is a fundamental science behind the concept of pH. Most often most people cannot even imagine how it changes. AND IT CAN BE USEFUL ON OCCASIONS as "myfamilysfarm" pointed out. OF COURSE you can always follow a recipe' directions BUT it is good to understand the fundemental. We often hear somebody asking I ADD A LITTLE BIT MORE ONIONS OR PEPPER TO MY SALSA RECIPE ...WHAT CAN I DO ? . If you know how pH/acidity changes work, all you can do is to add some more vinegar or lemon juice with confidence. So education and knowledge is always useful.

Sorry, I found that in a sample calculation online. You're right, a search showed 60. But the point is, who is actually going to calculate this? Again, if you are going by an approved recipe and just don't have 5% vinegar but something else, there are simpler ways to calculate how much (or if) to use a lower-acidity vinegar - of course you can always use higher (such as wine vinegar).

But you can't know how much more 5% vinegar to use if you have more low-acid veggies b/c the formula I used is for a weak acid in solution only, no solids. The NCHFP did give guidelines on how much lemon or lime juice (not vinegar which is not as acidic) to safely acidify a certain weight of onions/peppers. But you give no way to calculate it, and you would want to increase the amount of vinegar, not dilute it more, in such a case. So the table of values you give is interesting, if someone wants to use the very simple algebraic equation I used (correcting for molecular weight as you said) they can figure the pH of any concentration they want, but it's only theoretical, of no practical use in canning mixtures of low-acid solids that typically use straight vinegar (e.g., salsas) or half water/half vinegar (theoretically 2.5% but again I'm sure NCHFP built some leeway into those recipes to allow for more alkaline water - as Dave said, many municipalities keep pH over 7.5 to avoid precipitates) used in pickling, with a lower ratio of solids to brine than a mixture like salsa or sauce.

If someone wants the education/information to be able to judge if a recipe is acidic enough, they can see the NCHFP study on acidification of salsa ingredients I've linked below. To really be sure, you could take the MFP courses. And to make up recipes and be absolutely sure without testing the pH, you could get a degree in food science.

I'd love to take the MFP courses but they're not offered in my state. So I can go by the guidelines in the study, but I also like to ask MFPs and people with more experience because safe canning of low-acid mixtures is not dependent upon pH alone, but also density, processing time, processing method, etc.

As an engineer, don't you test prototypes rather than just relying on calculations/design before you build and field a mission-critical system?

Here is a link that might be useful: NCHFP Salsa Acidification study

This post was edited by ajsmama on Mon, Oct 21, 13 at 21:38

Fine. You do just that.
What did was I made a table for reference.
It is so obvious that pH does not change with small amount of additional water or ingredients. For example doubling water only changes pH by about. 0.15.

Well, a solution (I don't know if you're suggesting extrapolating to a mixture of liquids and solids, since you say people can use this table for peppers and onions?) that it 1/63 5% vinegar and 62/63 pH 7.0 something (water, asparagus???) is still very acidic 3.30 according to your table so does that mean that I can take a quart of asparagus (32 oz) and add 1 oz of vinegar and safely BWB it?

First you say that this is not a recipe, then you say that people can use it but you never give any calculations, just the table, and you don't say how to use it.

Enjoy your asparagus.