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Can Do!

Michigan State University Extension

JW: Whenever I visit someone's home and see a shelf lined with jars filled with colorful fruits and vegetables, I think, “Wow, someone put a lot of time and effort into doing that-- preserving their food, and won’t they be happy this winter?” I'm Judy Wagley. This is “From the Ground Up!” Kara Lynch is a registered dietitian and Food Safety Educator for Michigan State University Extension in Isabella County. Thanks for joining me again today, Kara. Last week, we talked about freezing, and today I'd like to talk about canning our food. Kara, what are the advantages of canning our food, our nature's bounty, regarding quality and nutrition?

Kara Lynch is a Registered Dietician and Food Safety Educator for MSU Extension
Michigan State University Extension
Kara Lynch is a Registered Dietician and Food Safety Educator for MSU Extension

KL: Canning is a great way to preserve food without having to rely on your freezer to store it. It becomes shelf stable. And so you can put it right into your pantry and enjoy it throughout the year. So that's great. Not everything can be canned, or some things require a pressure canner or something that maybe not a lot of people are comfortable doing. So that can be limiting for some people. But there are some types of produce that you don't necessarily want to can--onions, for example, you know, you can freeze those easily use them throughout the year. I mean, you certainly can, there are methods to do that. But it's not the same product. So it just depends on what you want. But there's a lot of types of produce you can can.

JW: Canning is a little intimidating for many folks.

KL: Yes, especially pressure canning. So there's really two different types of our methods of canning. We have water bath canning, which actually now-- there's also a method of the steam canning, which is really the same. It's recommended for the same types of products, which we call high acid foods. But then there's those low acid foods, and the only safe canning method for those is pressure canning. And that's what we hear from people a lot is the pressure canning is scary to them. Maybe they had an incident, or heard a story of someone's pressure canner blowing up. So yes, it can be scary for some people.

JW: What are the high acid low acid foods? Can you give us some examples?

KL: Certainly. High acid foods are going to be pretty much all of your fruits. When we say high acid, on the pH scale we're talking about a 4.6 acidity or lower, which means it's more acidic, the lower it goes on that pH scale. When it's above the 4.6 on a scale, they become low acid foods. Low acid foods are going to be all of your vegetables, all of your meat products and combination foods. Some of the other high acid foods that I should have mentioned but are also things that you pickle-- so that you make them. You take something that was a low acid food-- like green beans or cucumbers-- and you add an acidic solution to them, and they become a high acid food. So green beans for example--if you're just canning green beans, you have to pressure can them for safety. But if you're doing dilly beans, you can process them in a water bath canner. Water bath canners are not as intimidating; generally the processing time is much less. And it's a safe method that many people can do at home. And oftentimes, you can use your own equipment at home like a stock pot, for example, as long as you have a rack in the bottom of it, and the water can cover those jars by one to two inches. You can modify some of that equipment and do the canning.

JW: Kara what are the biggest safety issues in canning?

KL: The first and foremost is using a research-based recipe. With freezing you can get away with kind of going rogue and doing your own thing and it doesn't affect the safety of it. But with canning you have to follow a research-based recipe. Those recipes are created and tested in test kitchens, so that they know that the internal temperature of those jars has reached the safe temperature for the right amount of time. And if you're just say pulling a recipe off of Pinterest or the internet or your neighbor's recipe they've given to you- it isn't a research-based recipe. You don't know if it's the right solution, if it's acidic enough to be water bath canned for example, and what that processing time needs to be to be safely processed.

JW: It's amazing how our grandmas figured all of that out without all of that information!

KL: And that sometimes is the challenge, too, because we've learned a lot since our grandmas learned to can. And sometimes if we're only relying on the information that's been passed down to us, you can place any those people at risk that you're feeding your home processed food to. So the risk is foodborne illness and in particular, with those low acid foods, that's an environment where the bacteria Clostridium botulinum can harbor especially when we're canning. It's an anaerobic environment. And that's one of those bacteria that doesn't need oxygen to survive. And it can lead to botulism. And home canned products are the leading cause of botulism. And it's quite deadly. So I think it's just really important that people follow those recommendations and follow the research-based recipe. Use the appropriate method to process whether that be pressure canning or water bath canning.

JW: Speaking of grandmas, we find a jar of beautiful peaches that have been sitting on grandma's shelf for well, quite a while now. How do we know if those are still okay?

KL: That's a good question. And this also has kind of a two-part answer. The safety of can home canned items is more of a concern for the longevity of, of canned products than freezing is. But I will say that the recommendation is to only can what you're going to consume in a year. The main reason for that is because the nutritional value, the nutrients will degrade over time. So why eat something if you're not going to have you know, those vitamins and minerals preserved there, and other macronutrients?

JW: And you can do it all again next year anyway!

KL: You can, but the other thing is the quality degrades, like if you if you can something now and in six months, you compare it the color and then in another 12 months, you compare and the color certainly changes, it darkens and it's oxidizing. Also the texture will change-- the dryness, if something is sticking a little bit out of a solution, you know, that can change. So it's just not recommended. Now, the safety isn't something that we can definitely say, that in a year's time, you know, it's not safe anymore. Properly canned home-canned items can realistically be safe for an extended period of time. But there are some issues that can happen over time. I pulled up some canned pickles that were in the back of my pantry that had been hidden from my view, it was about four or five years old, and I pulled them out, and the rust had eaten away at the lid, there were holes in it. So it had been compromised that way. So, you don't always know. I've had people who have found their grandma's, you know, tomato sauce or something in her pantry and it was several years old. You know, it could be safe. But I guess my thing is, do you really want to take the risk?

JW: Yeah, and another reminder to always put the date on whatever you can.

KL: Yes, labeling and dating is critical.

JW: Kara, I know there are lots and lots of resources available about canning.

KL: There's a lot of information. We have a lot on our MSU Extension website, you go to our Safe Food and Water page. We have our Think Food Safety Facebook page, the National Center for Home Food Preservation, and Michigan Fresh which is another MSU publication. Those are where I would start.

JW: And you also offer classes?

KL: We certainly do. We have a weekly online free food preservation class throughout most of the year. You can access that either by going to our Think Food Safety Facebook page or our website and finding out more.

JW: Kara Lynch, food safety educator from Michigan State University Extension in Isabella County and registered dietitian. Thanks so much for all of your great advice and tips. And thanks for joining me today for “From the Ground Up!”

KL: Thank you.

MSU Extension Food Safety Hotline (open M-F from 9 a.m. -5 p.m.) Call 1-877-643-9882 –to ask questions

More information and links to many helpful resources may be found at--

Judy Wagley is WCMU's midday host, and is the producer of <b><a href="">The Children's Bookshelf</a></b> and <b><a href="">From the Ground Up!</a></b> She guides listeners through their weekdays from 9am to 3pm.<br/>