Q. I have been getting a lot of videos on my feed about dry canning. What is it, and isit safe?
The term “dry canning” can refer to either oven canning or a type of raw pack canning that doesn’t use added liquid.
Oven canning usually involves filling glass canning jars with flour, sugar, rice, beans, or other dry food, placing the lids, heating the filled jars in a hot oven, and allowing them to cool to room temperature. As the jar cools, a vacuum forms, the lid adheres to the jar, and it appears to seal. This method is not recommended for several reasons. Canning jars can tolerate high temperatures in a moist heat environment, such as boiling water, steam, or a pressure canner. Heating glass jars in the oven can cause them to shatter, creating an obvious hazard. Although the jars may seal, the contents within have not been processed sufficiently to destroy spoilage organisms. Moisture can be trapped in the sealed jars, which can encourage mold growth. When canning for long-term storage, a sealed jar does not necessarily mean the contents are safe. Some of the most dangerous bacteria, particularly Clostridium botulinum (a.k.a. botulism), thrive in an oxygen-free environment. Other spoilage organisms require very little oxygen to grow and can thrive in a sealed container.
If you want to store dry materials in glass jars, use a vacuum sealing device after placing an oxygen-absorbing packet in the container. Personally, I prefer to store these foods in the freezer in plastic containers since long-term freezing will prevent insect infestation as well.
Raw-pack dry canning involves filling glass jars with food (such as berries, vegetables, or fruit) without adding any type of liquid and processing in either a boiling water or pressure canner. The theory is that the heat will cause a sufficient amount of liquid to be released that the contents will be safely processed. Safe (tested and approved) canning recipes call for added liquid because the liquid allows for heat penetration throughout the entire jar, ensuring that all of the contents are sterile.
Use caution when researching canning recipes on the internet. I have seen an alarming number of AI generated recipes and articles that are very unsafe. Some of these even appear to reference known safe websites such as the National Center for Home Food Preservation (NCHFP). Unfortunately, widespread reliance on A.I. has created a confusing situation for anyone trying to find reliable information on anything, including canning. Always go to original sources, such as the NCHFP, university extensions, or Ball/Bernardin websites for the most reliable, up-to-date information on food preservation.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu