I understand that the way pickling works is by reducing food pH so botulism and other nasties cannot live in the food. A quick google search gives me pH 4.8 as the lowest that can host botulism. Does this mean that as long as I achieve pH 4.7 or lower, I am save just using BWB canning? or even just refrigeration?

I recently got a pretty accurate pH meter (SPER scientific large display pH pen). I have been using it for garden soil samples, but it can be cleaned well. I am also going to make/buy a buffer solution to increase the accuracy. I was wondering about measuring the pH of the food prior to canning, both for information/curiosity, and for safety reasons. Do any of you measure pH for canning/pickling purposes?

It turns out I do not like really sour pickles, or really acidic tomato sauces, so I would prefer to stay near the 4.7pH range, allowing 0.2 pH for meter accuracy. I also wanted to confirm that 4.7pH is safe enough. Thanks for your comments and answers.

OK, I said just one question but there is a related one. Since both salt and vinegar are used in pickling, and both have a preservation effect. Is there a way to measure the synergistic effect of both salt and vinegar? like if i use enough salt, I can raise the safe pH some?

No because first the minimum required pH is 4.2 or lower (which is why citric acid must be added to tomatoes that are normally 4.6-4.7) and second because the pH doesn't hold stable over storage time. As water and air leach out of the canned foods into the brine, the pH gradually rises back into the unsafe zone that allows for any botulism that was not killed during processing to thrive once again. So we process correctly to begin with to kill the botulism and then the change in pH is of no concern.

The use of a pH meter and even litmus paper was approved once upon a time but that approval was undermined by ongoing research and canceled several years ago. The FDA still allows meter (top of the line commercial ones) use in commercially canned high acid products but their use isn't approved for home food preservation.

Is there a way to measure the synergistic effect of both salt and vinegar? like if i use enough salt, I can raise the safe pH some?

Don't know but since there are recipes that do not use both - fermented pickles, kraut, etc. use only salt and water - I would assume the answer is no. At least not to any degree that would insure safety. But Linda Lou may have some info on that issue or you can always contact Dr. Elizabeth Andress at NCHFP.

Dave

I just measured the pH of the last pickling solution we made. It had gone trough the BWB process and been pickling the green beans and spices for over two weeks, so one would think it has equilibrated. The pH read 3.8 for an initial solution 1/2 water and 1/2 vinegar (white, 5%). I would not care for all vinegar, too sour for me.

The question was posed wrong by the way, I meant to say, what is the highest (not lowest) pH that I can have, and still inhibit botulism bacteria?

Appl Environ Microbiol. 1977 July; 34(1): 30-33

Effect of storage time and temperature on the survival of Clostridium botulinum spores in acid media.
T E Odlaug and I J Pflug
ABSTRACT

Clostridium-botulinum type A and type B spores were stored in tomato juice (pH 4.2) and citric acid-phosphate buffer (pH 4.2) at 4, 22, and 32 degrees C for 180 days. The spore count was determined at different intervals over the 180-day storage period. There was no significant decrease in the number of type A spores in either the tomato juice or citric acid-phosphate buffer stored for 180 days at 4, 22, and 32 degrees C. The number of type B spores did not decrease when storage was at 4 degrees C, but there was an approximately 30% decrease in the number of spores after 180 days of storage at 22 and 32 degrees C.

Here's the background. About 15 years ago, we started making salsa from a recipe (handwritten) that I have no idea where it came from. I love the recipe, but the original recipe didn't include adding any acidifier to the salsa. Not knowing any better(this was before the internet) the first year we canned it, there was lots of spoilage, which we had to throw out. When we made it after that, we always refrigerated it. A few years ago, I learned that low acid foods need to be either pressure canned or acidified. I had assumed since salsa was largely tomatoes, the amount of acidifier needed for salsa would be the same as for canned tomatoes. Today I read that since salsa has more low acid foods, it needs more acidifier. Unforturately, I've made several gallons of salsa this summer using the amount of acid recommended for canned tomatoes. Now I'm questioning whether it's safe. I know I could simply refrigerate it, but I don't have that much refrigeration space.

After reading this thread, I went down and opened a quart to test the pH. I've read the warnings on this thread about testing your own food, but I have a good pH tester that is calibrated with an accurate buffer solution. The salsa tests 3.8 pH. Learning from this thread that pH can rise over time, my question is, how much will it rise? I could test each bottle as I open it, but it's a hassle to recalibrate the pH meter each time. Is 3.8 pH a low enough starting point?

Thanks

And as to stability of pH, that all depends on storage conditions and age. Cool and dry and less then a year - probably. High humidity, brief exposure to heat or inconsistent temps or longer than year - probably not.

Alternative to dumping - open the jar, boil the contents for 15 mins., re-jar into new jar and into the fridge. I wouldn't but it is up to you.

Bottom line - no, it can't be guaranteed safe so it is your choice.

Dave

"if the toxin is present, it is killed by heating to 212 degrees F for 10 minutes. The C. botulinum spore, on the other hand, can live for hours at boiling. The whole idea behind canning foods that have a pH above 4.6 is to kill the C. botulinum spore -- which is killed at about 240 degrees F. Whether done at home or in a factory, the goal is to bring the food to a temperature that if a C. botulinum spore were present it would be deactivated so it couldn't vegetate and produce a toxin.

Amazingly you probably eat C. botulinum spores every day!!! Then why don't you become ill? The answer is that the spore ONLY grows and produces the toxin in the absence of air. Your body is full of air so the spore passes through causing no harm."

--> So it sounds like you could boil questionable foods for 10-15min to kill the toxin (which is the problem). The spores would still be around but as mentioned earlier in this thread (and in what I found) those are everywhere and aren't the concern that the toxin is. Right?

That means for a 150 pound person (68 kg), as little as 0.34 MICROGRAMS could kill. A microgram is one-onethousandth of a gram. A gram is a tiny amount to start with. It takes 453 grams of sugar to equal one pound of sugar, so try to imagine one pound of sugar. It is difficult to comprehend how tiny of an amount this is.

That means that if the toxin gets on your finger and you lick your finger, you may easily have ingested enough to kill you.

There is no recipe so good that it is worth taking the risk.

And I made a mistake - I should never write on forums when I'm at work because I'm distracted and make mistakes.

A microgram is one one-millionth of a gram, not one one-thousandth. Even tinier.

Sheesh, I KNOW this, can't believe I wrote it wrong.

I think using the proper procedures you could get the equipment, calibrate and standardize your meter, and develop an appropriate protocol for testing recipes. But at that point you'd be working for one of the food preservation labs.

I'm not trying to be negative because believe me I've thought about getting the meters and solutions myself. I just finally realized that it was just going to be easier to follow tested recipes or submit them for review. Its so disappointing though when you have a family or favorite recipe that you'd like to preserve. I should also mention that I tend to take a very conservative approach to things generally.

Sorry to be a stick in the mud. Hope things work out for you.

~Cindy