It may seem easier to measure only once but it isn't nearly as accurate to do so. You'd be amazed to know how many failures, both in quality and safety, results from mistakes in measuring. This is especially so with liquid measurements. So yes, since this is a safety issue, adding it to the individual jars is necessary. There is no way to insure accurate results otherwise. And it is very easy to do. Dave

When you boil vinegar, it evaporates and blasts you in the face when you approach the pan, right? I thought it must have a boiling point below the boiling point of water. But it turns out the boiling point of acetic acid is higher, so you actually can drive off some water and concentrate the acid. I posted a link below, but googling [acetic acid boiling point] will lead to info about why it has a higher boiling point, etc. According to the sources I found, the boiling point of pure acetic acid is 244°F. The acid in lemon juice is mostly citric acid. That is in solution, which means it's broken up and bonded with the water rather than actually being a liquid itself. It doesn't boil, it just breaks down into other substances at 347°F. Valereee, I'm with Carol on this one. I once made pectin-free peach-pepper jam that was too soft, so I cooked it longer and ended up making it caramelized and rubbery. I would use the NCHFP method. Melissa Here is a link that might be useful: boiling point of vinegar

Thanks. That's is what I was thinking too, but was hoping to confirm it from a more experienced crew than I! This will only be my third canning experience -- I put up jalapeno's last year. This year my garden is much more productive and so far I have canned 4 quarts of salsa using a recipe from the Bell Blue Book.

Wow! Didn't mean to start a brouha! ;) Just to stress the import of using the required acid. But discussing the acidity of a tomato in the context of taste as was the case in the quote above and in the context of canning are 2 very different situations. Numerous 'acid taste' discussions come up on the Tomato Forum. Can one taste the differences in acidic pH? NO. Can it make a difference in canning? Possibly if one is doing whole jars of yellow tomatoes and IF they are one of the higher pH varieties. But if you add the required acid to the jars then it is a moot point. The pH range of all tomato varieties is very narrow - something like 4.3-4.9 so no we aren't talking a huge diff here and it is very true that growing conditions can change the end pH of the fruit. But yes, there are charts of tested tomato pH's on the web - posted here in the past and in the full discussion that is linked below. But based on those tests and the obvious limitations of them, only a few reds (most commercial) fall into the highest range while several yellows do - again based only on the test results of a specific set of growing conditions so your results may vary. ;) And that variance is yet another reason that the acid is required. Dave Here is a link that might be useful: Tomato Acidity