Ianinfrance wrote:[---]
Hi Grisell,
I wasn't aware that proliferating c. botulinum gave off gas. I'm not saying it doesn't, I hasten to add, just that I thought that was what made it so potentially dengerous. I understood that the taste and appearance of the infected food was unchanged. I'd be delighted to be show I was wrong.
I have several sources that say that it in fact does. For example, quote from The Wordsworth Guide to Poisons and Antidotes:
"Even though botulism spores are invisible, it's possible to tell if food is spoiled by noticing if jars have lost their vacuum seal; when the spores grow, they give off gas that makes cans and jars lose the seal. Jars will burst or cans will swell. Any food that is spoiled or whose color or odor doesn't seem right inside a home-canned jar or can should be thrown away without tasting or even sniffing, since botulism can be fatal in extremely small amounts."
However, this requires that there was a 100 percent seal from the start. Any leak, and this would go unnoticed. In any case, I wouldn't rely solely on the absence of swelling as an indicator that the food is okay to eat.
PS Just recently, I read a book on polar exploration, the excellent "To the Ends of the World" by Richard Sale. There is a chapter about Franklin's lost expedition in the middle of the 19th century. They brought with them a lot of canned food that was made under inferior hygienic conditions (food canning was in its infancy). All the men perished and were never heard of again. One theory of their demise was botulism because of the canned food, however after recent exhumation of some graves and autopsies, it now seems more likely that their deaths were due to lead poisoning. The botulism theory is not mentioned in the Wikipedia article, which nevertheless provides some interesting reading:
http://en.wikipedia.org/wiki/Franklin%2 ... expedition