Doing a chemical conversion between liquid acetic acid (vinegar) and powdered citric acid is complex and easy to get wrong.

The easiest thing to do is, instead of vinegar, use lemon juice and/or lime juice, both of which are more acidic than vinegar. Many do anyway - I personally use 1/2 cup cider vinegar, 1/4 cup lemon juice and 1/4 cup lime juice. You can use any proportions you like, as long as you use one cup (in total).

Hope that helps.

Agree with malna. No safe way to covert from vinegar to citric acid without testing other than to say you would have to more than double the recommended amount since it is much more low-acid than just plain tomatoes. But how much more and how it would taste is unknown.

I have made it using 1/2 c bottled lemon juice and 1/2 cup bottle lime juice, all lime juice, and also using the 1/2,1/4,1/4 mix malna described. All are good. You can also sub cider vinegar for white for a more mellow taste.

Dave

PS: and welcome to the forum! :)

ok. thanks guys!