Lower acidity in overripe tomatoes makes them unsafe to can 

Care should always be taken when choosing produce for canning. It should be fresh, of good quality, and not overripe. This is especially important for tomatoes. The acidity of tomatoes varies during the growing season, and if overripe, they can become much lower in acidity and higher in pH. This lowered acidity level makes overripe tomatoes unsafe to can.

Besides being at peak ripeness, tomatoes for canning should be disease and damage free and have no mold growth. They should also not be harvested from dead or frost-killed vines.

While overly ripe tomatoes may be frozen or dried, the poor quality of these fruits may make for an unsatisfactory product. For best results, chose tomatoes that are firm and ripe (but not overripe).

For further information on canning visit the National Center for Home Food Preservation (NCHFP) at nchfp.uga.edu or contact your local Cooperative Extension office.
 Ask a Master Food Preserver
_________________________________________________________________________
Brought to you by the UCCE Master Food Preservers of El Dorado County
Last updated: July 2025