Testing the pH of foods for canning

[Sir GuitarCozmo]

I made up some pasta sauce this past fall, from garden fresh tomatoes.  I do not remember what all I put in it.  Canned them using a standard hot water bath.  I DID NOT pressure can them.

In recent months, it has come to my attention that pasta sauce can be susceptible to growth of botulism spores if you have 1) not ensured a pH of lower than approximately 4.6 and/or 2) pressure canned your jars, which allows the product to reach a temperature of around 240 degrees, which can kill the baddies.

With that, I'm not really not sure about my sauce.  I would like to open a jar and test its pH prior to just assuming it's safe to eat.  Litmus paper or pH test strips seem like the easiest thing, but since those generally rely on color changing, it seems that would be hampered by the fact that I'm testing red sauce.  I see a lot of digital pH testing meters on Amazon, but know little and the reviews are all over the place.

Anyone have any suggestions for how to safely test this sauce AND future food I plan on canning going forward?

[Chino]

I use these to test the water in my farms. Strips will definitely not work for you because of the coloring. To be honest, I'm not even sure these will work, since you aren't dipping them directly into water. Worth a try though.


https://www.amazon.com/Accuracy-Portable-Measurement-Resolution-Accuracy-tds/dp/B01EWZBB3S/ref=sr_1_7?ie=UTF8&qid=1485204006&sr=8-7&keywords=ph+meter

[Sir GuitarCozmo]

Hmph.  Well, the description does say this:

Patea Scope of application: pure water production and drinking, electroplating liquid, boiler water, fish tank water and swimming pool water, cleanliness, photographic liquid, wells, deep well water, laboratory, aquaculture, food processing, home, office, teaching, ionization water, cosmetics, city government water supply, travel health care

so maybe.

[Stadler]

Be careful, though; I'm no expert, but I understand that the pH at the time of canning is not necessarily static over time.  The pH can change (the best example, and how I know this, is pickles, where the water leaches out of the cucumber, and changes the pH of the brine).

[Sir GuitarCozmo]

Good to know, and that makes sense.  I got as much of the wet crap out of the tomatoes as I could, but it's still worth considering.

[millahh]

Analytical Chemistry Man to the rescue!!

The sauce is a suspension in water, so if you dab a little onto a test strip (say, using a toothpick), the liquid should wick out from the center, giving you a clearer view of the indicator at the edge of the droplet.  That said, Chino's answer should work.

pH changes can happen via reaction or neutralization (or by critters growing in there), but it takes a lot to do it...each pH unit is an order of magnitude change in H+ concentration.

[TempusVox]

Millah, so if you're saying it would take a lot of critters to alter the pH, could it not be altered and still pose a significant health risk? Doesn't sound like a sure fire thing to me.

Cosmo, is there a test lab in your area you might drop a jar off to and have it tested? May be expensive, but your health is worth it.

The most recently discovered type H is lethal at 2 billionth of a gram. Now you won't have that growing in the pasta sauce, but even if it's not enough to kill, if whatever type (A-G) is in there, it could still make you pretty sick.

[Stadler]

Analytical Chemistry Man to the rescue!!

The sauce is a suspension in water, so if you dab a little onto a test strip (say, using a toothpick), the liquid should wick out from the center, giving you a clearer view of the indicator at the edge of the droplet.  That said, Chino's answer should work.

pH changes can happen via reaction or neutralization (or by critters growing in there), but it takes a lot to do it...each pH unit is an order of magnitude change in H+ concentration.

I'm loathe to question Millahh; he's usually right on the mark in most things, but while he's factually correct, I still wouldn't f*** around too much with this.  You don't need a unit change to create problems, and you're already using a relatively inaccurate measure to start with, and you're right on the cusp of "good" versus "bad" (I didn't go back and look, but I think you said the threshold was 4.6; tomato juice is a pH of 4 +/-).   Plus, I gave the water in cukes as an example, but it's not JUST water that changes pH.   Anything that changes the balance of hydroxide ions (OH-) and hydrogen ions (H+) will change your pH.

Here's a thought:  aren't there any canning websites/forums (traitor!  don't cheat on us here!) that you can go to and pose the question? 

[Sir GuitarCozmo]

I could, but I'm hesitant to sign up to ONE MORE site.  Most would likely reiterate "follow tested, tried, and true recipes that are generally accepted as safe and you should be fine".  A homebrew forum I'm also a member of had several suggestions for litmus paper / test strips.

[millahh]

I realize I could have been a bit more clear regarding the pH changes:  I was specifically thinking of shifts occurring as the pickling solution gets more dilute from pulling the water out from the cucumber.  That is a small change in the overall liquid volume, in a system that is at least somewhat buffered (from the acetate in the vinegar)...so while there can be a subtle change in pH, it shouldn't be enough to be consequential.

As far a critters, they can affect pH over time, but if you start below the critical pH in the first place, they will never be able to proliferate.

[Sir GuitarCozmo]

So, if I were to open one and check it today, and it was below the recommended pH value, it should be safe to eat.  In that instance, I would probably, just to be sure, check the others, then pressure can them just to be extra sure.

[El Barto]

Why not just sterilize it now? A pressure cooker is a pretty nifty thing to own, so it's a reasonable investment.

[Sir GuitarCozmo]

I considered that, but was advised on the other forum I frequent, that

recanning it will just kill any potential bugs, but don't do anything about toxins already in there from existing

[El Barto]

I considered that, but was advised on the other forum I frequent, that

recanning it will just kill any potential bugs, but don't do anything about toxins already in there from existing

In that case are there any annoying dogs or cats in the neighborhood?

[millahh]

I considered that, but was advised on the other forum I frequent, that

recanning it will just kill any potential bugs, but don't do anything about toxins already in there from existing

In that case are there any annoying dogs or cats in the neighborhood?

You could try your hand at DIY Botox, maybe?

[Sir GuitarCozmo]

In all likelihood, I'm probably obsessing over nothing, but it will certainly not hurt to have a pH meter on hand for this kind of thing in the future.  Also, it can test the water in the hot tub and the pool.  Booyah.

[rumborak]

I must say, I have lately tried to entirely stay away from canned food. The amount of sodium in it is horrendous. I wish there was a "salt strainer" or something you could run the food through before using it.

[Sir GuitarCozmo]

You mean like homemade, mason-jarred things?

[rumborak]

Oh, jams and stuff are fine. I'm more talking about stuff that needs to be in brine to be preserved.

[Sir GuitarCozmo]

Analytical Chemistry Man to the rescue!!

The sauce is a suspension in water, so if you dab a little onto a test strip (say, using a toothpick), the liquid should wick out from the center, giving you a clearer view of the indicator at the edge of the droplet.  That said, Chino's answer should work.

pH changes can happen via reaction or neutralization (or by critters growing in there), but it takes a lot to do it...each pH unit is an order of magnitude change in H+ concentration.

I'm loathe to question Millahh; he's usually right on the mark in most things, but while he's factually correct, I still wouldn't f*** around too much with this.  You don't need a unit change to create problems, and you're already using a relatively inaccurate measure to start with, and you're right on the cusp of "good" versus "bad" (I didn't go back and look, but I think you said the threshold was 4.6; tomato juice is a pH of 4 +/-).   Plus, I gave the water in cukes as an example, but it's not JUST water that changes pH.   Anything that changes the balance of hydroxide ions (OH-) and hydrogen ions (H+) will change your pH.

I realize I could have been a bit more clear regarding the pH changes:  I was specifically thinking of shifts occurring as the pickling solution gets more dilute from pulling the water out from the cucumber.  That is a small change in the overall liquid volume, in a system that is at least somewhat buffered (from the acetate in the vinegar)...so while there can be a subtle change in pH, it shouldn't be enough to be consequential.

As far a critters, they can affect pH over time, but if you start below the critical pH in the first place, they will never be able to proliferate.

You guys and all your fancy book learnin' and shit.  You may as well have said:

It is possible to synthesize excited bromide in an argon matrix. Yes, it's an excimer frozen in its excited state. It's a chemical laser but in solid, not gaseous, form. Put simply, in deference to you, Kent, it's like lasing a stick of dynamite. As soon as we apply a field, we couple to a state that is radiatively coupled to the ground state. I figure we can extract at least ten to the twenty-first photons per cubic centimeter which will give one kilojoule per cubic centimeter at 600 nanometers, or, one megajoule per liter.

[Stadler]

I have this mental picture of me and Millahh standing there, looking like Leonard and Sheldon from Big Bang Theory, and Coz standing there looking, well, pretty much like his avatar, and every time we say "hydrogen ions" or "hydronium", he rips off a bitchin' solo that CC DeVille would have been proud to call his own.   

[Sir GuitarCozmo]

CC would've been proud to call any bitchin' solo his own. 

Reminds me:  The Guitar World's 100 Worst Riffs, Licks, and Solos article from MANY years ago, had this to say about Warrant's "Cherry Pie":

Imagine how insulted Erik Turner and Joey Allen felt when they were told Poison’s C.C. DeVille would play the solo on this song. That’s like having your wife tell you Gary Coleman will be taking over your bedroom duties.

[Stadler]

HAHA, I was grasping for a hair metal icon.  I'm not the biggest DeVille fan.  My fave hair metal guitar player is either Tom Keifer or John Sykes.

[millahh]

CC would've been proud to call any bitchin' solo his own. 

Reminds me:  The Guitar World's 100 Worst Riffs, Licks, and Solos article from MANY years ago, had this to say about Warrant's "Cherry Pie":

Imagine how insulted Erik Turner and Joey Allen felt when they were told Poison’s C.C. DeVille would play the solo on this song. That’s like having your wife tell you Gary Coleman will be taking over your bedroom duties.

That was the same EXACT thing I though of when Stadler said that...CC DeVille: STUNT COCK

[Sir GuitarCozmo]

And yeah, John Sykes is f*cking awesome.  His live solo on Cryin' in the Rain in Rio says all anyone needs to know.

[El Barto]

And yeah, John Sykes is f*cking awesome.  His live solo on Cryin' in the Rain in Rio says all anyone needs to know.

I couldn't figure whose throat Coverdale was threatening to cut, but after hearing him sing I sure hope for his sake it was the monitor man. Dude gave a bad name to train wrecks. Big Sykes fan, though. Loved his stint with Thin Lizzy. The solo on Cold Sweat is exactly how it should be done.