Canning season throughout the U.S. will start in the next month or so. In the past couple of years I’ve taken up the science-based art of preserving food in glass jars.  At first, it was out of necessity, so I’d know a bit about some of the questions I was getting from folks across the state; it’s now a hobby. I’ve got a weighted gauge pressure canner, a bunch of accessories and I think I’m going to get into dehydrating stuff this summer.
Like cooking, I’m getting better at it with practice. Unlike cooking, I don’t mess around with experimenting. I don’t pretend to be Bobby Flay in the kitchen (guessing at ingredient amounts, etc.) when it comes to preserving stuff in an anaerobic environment. I prefer to stick to the tested, evidence-based recipes. Mainly because I don’t want botulism.
Though reliable data is often hard to access, recent outbreaks linked to the potentially complicated processes of home preservation have contributed to the national burden of foodborne illness. In 2009, a Spokane, WA nurse and her two children became ill with botulism reportedly acquired from canned green beans; the mother’s illness was so severe that she required a ventilator to breath for months. In September 2008, an Ohio man and his grandson were hospitalized as a result of botulism toxin poisoning caused by improperly canned green beans. In 2007 a Virginia couple died after consuming improperly canned foods that also contained botulism toxin.  There have been at least seven other outbreaks of botulism linked to home preservation practices across the U.S. since 1995. Improperly processed home-dried jerky products have also recently been linked to Salmonella and pathogenic E. coli outbreaks.
A historic C. botulinum-linked outbreak was featured in Sunday’s Detroit Free Press turn-back-the-clock column. According to the Freep, one of the largest botulism outbreaks in the U.S. began on March 28, 1977. 59 Illnesses were linked to hot sauce served at a Mexican restaurant. The sauce was made with jalapenos that were improperly canned:
Trini and Carmen’s restaurant had previously used fresh peppers, but switched to canned ones March 28.
The vegetables were canned in the fall of 1976, in anticipation of an expected shortage of jalapeños that winter. The outbreak was the second one in the U.S. that year caused by incorrectly canned jalapeños.
In a paper in published in the Am. Journal of Epidemiology detailing the outbreak, investigators found that some of the jars of jalapenos were filled and sealed with no processing. Peppers, a low acid vegetable, need to be processed using a pressure canner to inactivate C. botulinum spores. A boiling water bath wont do the trick (as it wont get the product hot enough). Filling and storing on the shelf is definitely a risky practice.
According to the investigators, the restaurant had some risk management practices in place, "After a number of days, some of the jars began to explode on their shelves. … The jars that did not explode were kept."