Last week we covered important aspects of preventable foodborne illness, specifically botulism, which is caused by a toxin produced in food by the bacteria, Clostridium botulinum. Using approved recipes and approved procedures makes botulism nothing more than an interesting topic. This week we finish up. For those of you who think botulism only results from improperly home-canned food and have therefore decided to avoid Aunt Mabel’s green beans forever, read on! Her properly home-canned food might be the safest food around.
Botulism has occasionally been caused by foods that were not vacuum-sealed by caning. Smoked fish can develop anaerobic conditions under the skin and in the visceral cavity. Baked potatoes wrapped in foil and meat pies have also been the cause of botulism. A large pot of sautéed onions left in a warm place resulted in botulism cases from persons eating the onions. Garlic in oil also caused multiple cases of botulism at a Canadian restaurant. Pickled eggs left at room temperature developed botulism in the yolk, which had been pricked with a toothpick, before the acid pickling solution was able to equilibrate throughout the egg.
Each of the above instances was preventable. Repeat the mantra: “Wash, scrub, refrigerate or freeze.” To prevent botulism toxin from forming in non-canned foods, low-acid foods must be refrigerated after they are cooked. Long-term storage of smoked fish should be in the freezer. This is because type E Clostridium botulinum, which is found in fish, can produce toxin at refrigerator temperatures. Smoked fish can be safely stored in the fridge for up to two weeks.
For low acid foods that are pickled, vinegar must be added in sufficient quantity to lower the pH to below 4.6. The vinegar in pickling recipes must be at least 5 per cent acidity. Approved pickling recipes are provided by Extension offices or the USDA Complete Guide to Home Canning.
Botulism symptoms include difficulty in swallowing, speech, and respiration and double vision. Respiratory failure may cause death. Before 1950, fatality rates from botulism were about 50 per cent, but with availability of antitoxin and modern respiratory support systems, the death rate has decreased to about 10 per cent. Still, if you are in that unlucky percentile, your death is 100 per cent guaranteed, and that is not good.
If you cannot get enough of this fascinating topic, additional information can be found in The Bad Bug Book, www.cfsan.fda.gov/~now/intro.html