tartaric acid in grape jam
I see you have been waiting two weeks. I heard that our food safety specialist is doing experiments to give you a research based answer. Sorry for the wait, answer should be coming soon.
Hi there! I am so sorry - we having been trying out a few things, but the source grapes did not crystallize, so we weren't able to get an accurate evaluation of the process. I am working on sourcing some new grapes to try again.
Here is the situation - some of which I am sure that you already know - for juice and jelly processing, cold stabilization is the best approach. Cold stabilization means collecting the juice and holding at refrigeration temperatures for 1-5 days to force the crystallization to happen and then the resulting juice will be stable. This doesn't work for grape jam because you aren't juicing them ahead of time. I went to the wine literature to look for tartaric acid stabilization options and found a decent lead for adding a small amount of carboxymethylcellulose (CMC); however, this hasn't been tested in a jam system, nor has it been tested with CMC products that are readily available to the public. We are trying this out (as soon as we get some more grapes)!
Please stay tuned. I'm sorry for the delay, but I definitely want to see if this works!!