For years I used to can with some fairly renegade methods. My youthful convictions and attitudes encouraged me to question the authorities. Some of these methods were actually older techniques brought forward (and accessed by me) in canning books found at used book stores and garage sales: set cans upside down for better seal, open pot water bathing is OK, tomatoes can be water bathed, etc. For some reason, I felt that the older the book the better the advice. After all, those new federal guidelines were all about fear and preservatives! Luckily, I’m still alive.
What really set me straight about food safety and canning was the realization that canning is based on scientific research and technique; it is a home-industry preservation process not a cooking technique. In canning, there is no room for improvising recipes and winging it. After completing the Oregon State University Lane County Extension Master Food Preserver program, I had new respect for and greater understanding of home food preservation and food safety. There was one particular half-hour media presentation I viewed that was quite memorable: A woman who had contracted botulism from an undercooked baked potato related, in graphic detail, her months-long struggle to stay alive. My knees were shaking and I had broken out in a cold sweat by the end of the video.
I have been an avid steam-canner user at times and found the process water, time, and energy efficient. However, I discontinued my use of that method when I was not able to access supportive research on steam canning. Every few years I have checked back in to see if the situation has changed. These days, I am especially interested in any topic related to steam and food because of the Mehu-Liisa Steam Juicer I sell. Recently, I was happy to find reliable resources that indicate that steam canning is now recommended with some restrictions and guidelines.
One question about steam canning was whether it could raise the internal temperature of jars to the proper degrees and then hold it there for required processing times. A recent article—from 2014—on the Clemson University extension website (http://tinyurl.com/gs7vw2p) states, “steam canning . . . causes underprocessing and is not sufficient to kill spores of Clostridium botulinum. Underprocessing low acid and borderline acid foods can lead to botulism food poisoning.” So, as late as 2014, the USDA and many university extension services recommended that steam canners not be used.
In 2011, the University of Wisconsin Extension started to research the effectiveness of the steam canner (officially termed, atmospheric steam canner). Barb Ingham headed the project. The results of the study were published in June, 2015. The study determined that, if specific guidelines were followed, the atmospheric steam canner could be used safely. This was a welcome acknowledgement from food preservation and safety authorities for the many folks who, having trusted gut instinct or a renegade voice, are regular steam canners. It must be emphasized that the process is deemed safe only when specific guidelines are followed: only naturally high-acid foods or acidified foods (salsas, pickles) should be used, only research tested recipes for water-bath canning should be used, all steps in the water-bath canning process must be observed, and processing time must not exceed 45 minutes.
So, yes, when following specific USDA guidelines, atmospheric steam canning can be a safe method. Please follow this link to view the recommendations for safe use of an atmospheric steam canner as posted by Barb Ingham of University of Wisconsin Extension:
I’ve always told my customers to be safe and follow the USDA recommendations for canning fruit juice. But, I’ve always said this with a bit of that old renegade attitude lurking in the back of my mind . . . Water-bath canning is such a waste of time and energy . . . all that dangerous, heavy boiling water! Drawing hot juice straight from the juicer into sanitized canning jars and capping with boiled dome and band lids is safe enough, isn’t it? At this time, I don’t have an answer to that question and so my recommendation is still to follow the USDA guidelines for safe food processing. But now, I can mention that the water, energy, and time efficient method of atmospheric steam canning is one of the methods that the USDA supports.
Perhaps someday soon, I will be involved with a research project to determine the safety of canning juice straight from the Mehu-Liisa Steam Juicer. Let me know if you have a friend or associate who would be interested in a project like this. Keep in touch!