Canning tips from a U of M food science educator
With the season for fresh fruits and vegetables on its way out, Hot Dish wanted to find out more about produce preservation and touched base with Suzanne Driessen, a Food Science Extension Educator with the University of Minnesota.
U of M Extension Canning is not cooking: It's more serious business.
Driessen pointed us to tons of resources on canning, everything from the U of M's Extension Services website to Lanesboro-based canner Peggy Hanson's blog. But first, she answered a few of our questions to take some of the mystery--and fear--out of canning.
Why is canning becoming more popular?
Preserving food for later use is very popular again. I don't have any hard data to support this, just anecdotal. Someone in my Winona class said there wasn't a freezer bag to be found at his grocery store over the weekend. Many stores that did not previously carry food preservation equipment now do. Our requests for classes and information have doubled from last year. People are interested in growing or buying local foods for freshness and to support local growers. In the classes I teach, I ask participants 'why' do they want to preserve food. Common responses include: tastes better, you can control and you know what's in it and it's healthier. A sense of pride and preserving lost traditions also is frequently mentioned.
What keeps people from home canning? Equipment? Knowledge? Fear?
Not knowing what canning is or how to do it is commonly mentioned in my classes. I taught a class in Minneapolis where 23 people from the metro area attended--two had canned using the boiling water method and no one had used a pressure canner. People are hearing about canning and wondering what it is, how to do it and if it is right for them. I had a couple take the same class last year and took it again this year because they still weren't quite comfortable trying it on their own yet. After this class, they said they were ready to try pickling beans.
Remembering grandma's or mom's pressure canner exploding its contents to the ceiling is mentioned a lot--that won't happen today with newer models as they feature a pressure release value, if the pressure gets too high this valve is released to bring down the pressure. Don't be afraid--pressure canners are safe to use; follow your manufacturer's directions, work and watch an experienced canner do it to see the process and gain the confidence to do it.
What are the risks associated with improper canning?
According to the National Center for Home Food Preservation, in the past two years, there have been three botulism food-borne illness outbreaks associated with improperly home canned green beans. Clostridium botulinum is the bacterium that causes botulism. The spores are found naturally in our soil. The spores will only germinate in airtight conditions, which we create in canned foods. They will only grow in low acid foods like vegetables, meat, fish, mixed foods like soups, spaghetti sauce with meat, etc. The spores can be destroyed at 240 degrees F. We can only reach this superheated temperature under pressure using a pressure canner.
C. bot. won't grow in high-acid foods like fruit, jam, jelly, and pickled foods or salsa where we add vinegar to make it acidic. So these foods can be safely canned using a boiling water canner. Processing these foods in a boiling water bath canner is needed to destroy heat sensitive bacteria like Salmonella and spoilage bacteria like yeasts and mold. It also inactivates the enzymes that make our food soft, mushy and yucky.
What are the most common mistakes new canners make?
Googling recipes, using mom's or grandmas old recipes or making up a canning recipe. There are tons of recipes, blogs, videos on canning on the Internet. Some are great, some are not. Just because it is in print doesn't mean it is safe.
Look for sites that reference tested research recipes and methods. University and canning supply companies are reliable sites. Canning is not cooking. Creating your own canning recipe is dangerous. Adding extra garlic or onion to pickles could change the acidity level and bring it into the low acid category. Recipes are tested for safety and for the best quality. You want your canned product to be safe but also to taste good too. Old recipes are no longer safe to use. In the late 1980s, canning recipes and processing times were retested due to increase incidence of food-borne illness associated with home-canned foods. The revised times and methods were released in 1994. So for safety sake and to relieve fear, use tested recipes and resources dated 1994 or newer.
What foods will be at their peak for canning in the upcoming weeks? Which foods do you recommend for new canners?
Tomatoes, beets, peppers are ready. Because of the rain and warm weather vegetables are ripening faster. Tomatoes are the most popular food canned in the United States. Maybe start with the Minnesota Tomato Mixture recipe. It is tested and can be safely canned in a water bath canner. Be sure to follow instructions exactly.
If you want to make salsa, be sure to use an updated recipe. Paste type varieties, green tomatoes, tomatillos are great for salsa. If you like a thicker salsa, thicken with commercial tomato paste. You can substitute the type of pepper you like depending on how mild or hot you like your salsa. Do NOT add extra low-acid ingredients like onions, garlic, etc. You can add less but never more of these ingredients because it can bring it in the low-acid category.
I freeze most of my tomatoes. But I love tomato juice so I can it. Most tomato varieties we grow today are on the borderline between low-acid and high acid. Some varieties are low-acid. So to ensure proper acidity ALL tomato products need to be acidified. We have three options: [ed: see tomato graphic that accompanies this article].
What books, classes, or online resources would you recommend for aspiring canners?
If you are just starting out, I recommend the Ball Blue Book. It is inexpensive and has great pictures and step-by-step directions. (Remember to adjust for our Minnesota altitudes; choose processing times for 1001 - 2000 feet; usually you add 5 minutes processing times to recipes that aren't from our University of Minnesota Extension website. If you choose recipes and times from our website, we have already adjusted for Minnesota altitudes.)
I love the So Easy to Preserve DVD and book. Ask your library to order the DVD so you can check it out. It shows step-by-step instructions on freezing, drying and canning.
The National Center for Home Food Preservation does the research and provides tested recipes and methods on their website. You can find how to use a pressure canner and boiling water canner and information and step-by-step instruction for using canners and 'how to' can a variety of food. Access the latest edition of the USDA Complete Guide to Home Canning.
Also, check out my 5-minute mini-modules [scroll down for a list of the narrated slide lectures] on 18 topics of food preservation.