Interesting article on it linked below. If I understand it correctly the pectin in your peaches kept the natural pectin (PME) in the tomatoes from being destroyed by the heat thereby allowing it to contribute to the gelling process.

tomatoes have another enzyme as well, a polygalacturonase (PG), which causes some trouble. If I got it right this enzyme degrades the pectin gel (and plays an important role in the ripening of tomatoes). One therefore needs to inactivate the tomato PG enzyme and this is done by heat. Regrettably this also knocks out the PME of tomato, but this is were the carrots and oranges come in � they have PME, but no PG. Hence they hold the key to unlock the gelling properties of tomato. So to sum it up, you can use enzymes present in carrot and orange juice to chemically change the pectin of tomatoes to make it more prone to gelling in the presence of calcium ions.

So tomatoes alone? No, any natural pecticn they have would be destroyed by the PG and heat. The yellow tomatoes would likely (just a guess) less PG since it is tied to the color of ripening. But when mixed with other things that have no PG (like carrots, oranges and perhaps peaches) it isn't destroyed.

If correct then theoretically if the peach-tomato salsa was made with red tomatoes the effect wouldn't be as great.

Dave

Here is a link that might be useful: Tomato gels with natural pectin

Fascinating article, thank you!

huh. I didn't know you could alter Annie's salsa to include peaches. I would have thought that it wouldn't be safe, as I thought peaches were low acid....

Peaches like most all fruits with a few exceptions are high acid.

Dave

Ah! I didn't realize that! (clearly...). Good to know!!