I've noticed that the new "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, contains recipes for making pickled products containing oil. I've always been taught that oil should not be added to home-canned food because it protects the spores of the bacteria that cause botulism food poisoning.
You are right to be concerned. However, new research at Pennsylvania State University has found that with safe, tested recipes that contain a high level of acid, oil can safely be added to some products. Acidifying foods lowers the heat resistance of C. botulinum. The recipes in the "Complete Guide to Home Canning," which can be found on the National Center for Home Food Preservation website, have been thoroughly tested and are safe. However, beware of recipes from other sources. Check with your county extension center before using them.
Barbara Willenberg, Nutritional Sciences, University of Missouri-Columbia
Last update: Tuesday, May 05, 2009