Is it safe to apply oil and herbs to tomatoes before drying?
Mary Meehan-Strub (LaCross County) was one of the individuals with this question recently. Sun-dried or dehydrator-dried tomatoes with oil are a real delicacy, but they can be hazardous if not properly prepared. Coating tomatoes with oil during the drying process will slow the drying process and for this reason alone it is not recommended. And, more importantly we have to worry about Clostridium botulinum and the production of botulism toxin. If foods are not properly dried, if they have a pH>4.6, and if oxygen is excluded from the environment, we can have the production of toxin from Cl. botulinum spores. Oil is effective at ‘sealing’ an environment so that air doesn’t get in; this is the same reason why we used to use paraffin on jams and jellies. If the tomatoes are not dried enough (because the oil is there) and if the pH is not low enough, then dried tomatoes in oil can support the production of botulism toxin. So the only way to safely prepare tomatoes this way is to dry the toma
