Yesterday I gathered with 27 other folks for the Master Food Presever class, through the WSU Extension office. The first class was a bit of a wake up call. I went in with nostaligic longings to connect with a heritage of community resourcefulness; Canning the Kaiser from WWI, Victory Gardens from WWII, and all that. The first class was more about food safety so I came away realizing that, if you don't do it right, canning is a good way to "can" your close friends and relatives with some nasty bacteria. We learned some common myths that are good to know about.
1. Just because the jars are sealed does not mean the food is OK. The heat penetration makes the food safe by killing all the bacteria, the seal keeps it safe. If the food isn't safe in the first place, the seal doesn't matter. Some methods that may get a seal but don't kill bacteria are using an iron on top of the can, using the oven to heat them up, and running them through the dishwasher (yes someone actually did that.) Basically, any method other than the one specified in the recipe from a science based source, is unsafe. They actually put probes into the cans with the particular recipe to take the temp throughout the can, and determine how long it takes for the heat to penetrate. Different foods conduct heat at different rates so no guessing allowed.
2. Just because you've used the same recipe and method for many years without problems does not mean it's safe. We heard the story of a couple who used the same unsafe recipe for 50 years without a problem, but year 51 was a killer.
3. Just because one can is OK, doesn't mean the whole batch is OK. We learned about someone who ran out of brine on the last can of pickled asparagus and added water to top it off. That was just enough to dilute it and make that one can out of the batch toxic.
4. Just because the food looks fine doesn't mean it's OK to eat.
5. Just because your friend that gives you homemade pickles is too nice to try to kill you, doesn't mean that they won't inadvertently put you in danger with their family recipe from the 1800's.
I guess the big lesson is that you have to follow the proven canning recipes. Save the culinary flourishes for when you serve the food. The good news is that if you follow proven recipes faithfully, you are guaranteed safe. Two reliable sources of safe recipes are www.homefoodpreservation.com and the Ball Cook Book. Both sources are backed up by good science. There is a book and DVD version of the home food preservation web site called So Easy to Preserve. Old canning cook books are not a good source of recipes because of changes that have been made in the guidelines due to new research. If you have any food preservation questions you can call 866-986-4865 and talk to Master Food Preservers of Eastern Washington.
Eastern Washington asparagus is in stores now, so it's time to break out the cans and get pickling. Go here for the basic recipe for pickled asparagus. Or if you're into freezing check out these instructions on how to freeze asparagus.