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Safe Canning and Preserving. What people are doing wrong.

Canning and preserving your own food can be a healthy, economical and fun fall activity. If you have a backyard veggie garden or frequent your local farmer’s market, canning and preserving can be a great way to eat local even when winter has local food options limited.

However, safety is an important but often neglected part of the at-home canning and preserving process. In this age of DIY-everything and Internet ‘experts’ around every corner, it’s easy to think that you can just dive into canning as you would baking or making your own glass cleaner.  

When it comes to preparing shelf-stable foods (that is, food that will stay ‘good’ for months or years without refrigeration or dehydration) if you’re not careful, food poisoning is a real and potentially life-threatening risk.

Luckily there are simple steps you can take to make canning a safe and fun activity for you and your family to enjoy.

Benefits of canning and preserving

While it is of utmost importance to approach home canning and preserving properly, don’t let our warnings scare you off. There are a lot of benefits that can come from canning at home and later on in this post we have helpful pointers for canning safely.

According to the USDA, “canning can be a safe and economical way to preserve quality food at home. Disregarding the value of your labour, canning homegrown food may save you half the cost of buying commercially canned food.”

If you grow your own produce, canning and preserving can help you save your harvest so none of it goes to waste. Sometimes, when growing your own fruits and vegetables, your crops can all come in at once. When this happens, often you’re unable to use everything before it starts to go bad. Canning allows your home-grown goods to be available all year round.

On that note, canning and preserving is also eco-friendly. According to Life + Health, “Canning your own food is an excellent way to reduce your environmental impact. Especially if the food is home grown, you remove the countless miles food is shipped from the farm, to the factory, and then to the distributor and local store. You also reduce packaging waste because canning jars (except for the lids) are reusable and will last for years.”

Even if you don’t grow it yourself, buying your produce from local farmers has similar environmental benefits and also means that your food will be more nutritious. Shipping foods long distances has more of an impact on their nutritious qualities than almost any other factor (e.g. more so than organic certification or other growing conditions).

What’s also great is that you have more control over the ingredients in home canned products. While canning and preserving isn’t always the healthiest option (many canned goods are high in salt or sugar), when you do it yourself, you can control exactly what’s in the goods you’re eating. There won’t be any harmful additives or preservatives in your homemade canned goods for one thing and you can seek out reliable recipes that use less sugar or salt or other ingredients you may be trying to avoid (as long as you are using safe recipes… see below for more on that).

Finally, homemade canned goods make thoughtful gifts. With all the time, effort and caution that goes into this process, a nice jar of jam can make a wonderful present. Giving each person on your list something that you know they will personally enjoy is sure to please.

How canning at home works

When it comes to canning your own food, it’s not hard but it is scientific.

The simplest method of canning is known as water bath canning. According to Mother Earth News, “you fill jars with acidic food such as tomatoes, berries or cucumbers in vinegar, cover them with lids and boil them in an open pan of water until a seal forms under the lid. This action forces air out of the food and out of the jar and creates a vacuum in an acidic environment in which bacteria will not thrive.”

Water bath canning is ideal for jams, jellies, pickles and mustard. You can do some tomato recipes in a water bath but you must add acid, in the form of lemon juice or vinegar as tomatoes on their own are not acidic enough (contrary to popular belief).

A more advanced method is known as pressure canning. This method requires specialized tools to do properly and is usually the realm of more advanced canners. For many foods — i.e. those that are not very acidic — pressure canning may be the only safe way to can them at home. These foods include vegetables, meat and seafood. Exceptions may be made for some vegetables if enough acid is added to the food before canning (as with tomatoes).

Pressure canning involves much higher temperatures than water bath canning. It uses less water and the jars are heated with steam. Temperatures reach 240°F so it can safely kill any organism (e.g. botulism spores) without the need to add acid. Pressure canners are more technical to use and require a bit more of an investment because they can really only be used for the one purpose.

If you’re new to the canning and preserving world, water bath canning is probably the best place to start.

The Risks

The biggest risk, when it comes to food spoilage and home canning, is botulism poisoning.

According to the Mayo Clinic, “botulism is a rare but serious condition caused by toxins from bacteria called Clostridium botulinum.” Foodborne botulism, in particular, is caused by the harmful bacteria that thrive and produce the toxin in environments with little oxygen, such as in canned food.

While your garden-variety food poisoning can be terribly unpleasant, causing cramping, vomiting, diarrhea, fever and muscle weakness, it’s rarely life-threatening except in severe cases or when it affects pregnant women (where it can cause stillbirth), young children, the elderly or people with weakened immune systems.  

Botulism, which is rare but the most likely type of food poisoning to occur from home canned goods is more dangerous and also harder to detect. Botulinum has no smell or taste; food contaminated with it may seem perfectly normal and tasting even a very small amount can be extremely dangerous.

According to the CDC, “Home-canned vegetables are the most common cause of botulism outbreaks in the United States. From 1996 to 2014, there were 210 outbreaks of foodborne botulism reported to CDC. Of the 145 outbreaks that were caused by home-prepared foods, 43 outbreaks, or 30%, were from home-canned vegetables. These outbreaks often occurred because home canners did not follow canning instructions, did not use pressure canners, ignored signs of food spoilage, or didn’t know they could get botulism from improperly preserving vegetables.”

Botulism causes paralysis, so the first symptoms are often drooping eyelids, blurred vision, slurred speech and difficulty swallowing. The sufferer will not likely have a fever and they will usually seem alert and aware of their surroundings.

Even with treatment, symptoms can last for years and death is a very real possibility.

How to stay safe

As we’ve mentioned, you can’t just jump right in and start canning foods. There are quite a few precautionary steps before you get started, in order to avoid food poisoning or botulism.

First, you should only use recipes that have been scientifically tested, proven successful and come from a legitimate source. There are plenty of sources claiming their recipes are safe, when in reality, they aren’t. Really, any canning recipe should have been tested in a lab. This is not the place for ‘winging it’.

Homemade canned goods that have spoiled may not show obvious signs. That’s why using only reputable sources and following instructions to a tee are of utmost importance to confidently prevent botulism.

A great source for recipes is the Ball Blue Book, which is packed full of delicious recipes for sauces, pickles and preserves. The recipes are all lab-tested and proven safe, so your canning and preserving endeavors are sure to be safe, as well as delicious.

Bernardin, a Canadian canning supply company, also has canning recipe books that all meet or exceed the USDA standards for safety.

Healthy Canning has a comprehensive list of great online sources for canning and preserving at home. These are all reputable sites that can be trusted to post only safe recipes that have been thoroughly tested.

According to the USDA, an extremely important step in the canning process is the sterilization of food.

“Botulinum spores are on most fresh food surfaces. Because they grow only in the absence of air, they are harmless on fresh foods. […] Properly sterilized canned food will be free of spoilage if lids seal and jars are stored below 95℉. Storing jars at 50℉ to 70℉ enhances retention of quality.”

So what does that mean for you, the newbie home canner? It means:

  • the food itself must be sterile when it goes into the jars (i.e. your jam has to go in hot)
  • the jars and lids themselves must also be sterile
  • once properly processed and sealed, the jars should be stored in an appropriate place where temperatures won’t go above 70° F (21° C)

When it comes to preparing the food before you put it into your jars, you need an acidic environment (your recipe should tell you how much acid to add, usually in the form of vinegar or lemon juice) and temperatures need to reach a level that will kill any spores on your produce. Botulinum spores like moist, low-acid environments where there is little to no oxygen (i.e. the inside of a sealed jar) and temperatures between 40° and 120°.

While sugar can suck up water, which may help to prevent botulism growth, it is not sufficient to keep your preserves safe in the absence of acid. This is a common misconception.

It’s also important to properly prep your cans and lids. Canning Homemade! says you want to make sure your jars are hot when adding your food to them and that “you can clean and sterilize either by running them through the dishwasher that has a sterilization setting or sterilizing them in the water bath canner[…] Leave them in the canner or in the dishwasher with the lid on or the door shut till you are ready to fill them.” You can also sterilize your (washed) jars in the oven by putting them into a pre-heated 225° oven for at least 20 minutes. Leave them in the oven with the door closed until you are ready to fill them.

In terms of the lids, you have to prep those, too. Boiling them sterilizes them and softens the rubber outer seal so they’ll adhere to the rim of the glass jar. You can add the lids to your canning pot after the jars have sterilized or you can boil water in a separate pot on your stove, turn the water off and add the lids to the boiled water, leaving them there until you’re ready to seal your jars. Unlike the glass jars, metal and rubber lids can only be used once (though the rings can be re-used).

Once ‘processed’ (the term for sealing your jars in your water bath or pressure canner), you should make sure that each jar seals completely (the little dome on top should be flat so that you can’t depress it with your finger). You’ll hear each jar ‘ping’ as it seals, either in the canner or shortly after you take it out. Store your jars with the rings off or at least loosened — they have nothing to do with maintaining the seal and may artificially keep unsealed lids on tight.

When it’s time to eat your home-canned goods, be sure to inspect the jar thoroughly. Make sure that the lid is still sealed, with the dome flat. Any signs of leaking or damage are an indication that the jar should be thrown away. If, when you open it, it spurts or foams, likewise, throw it away. If you see any signs of discoloration, mold or bad smells, toss it (though remember, botulism contamination may not cause the food to appear spoiled so the first steps should also be followed). There are instructions online for how to throw potentially contaminated food away safely.

While we’ve covered a lot in terms of what you need to know in terms of canning, it’s still important for you to find step-by-step instructions from a reputable source every time and follow the steps and recipe exactly.

Good luck and happy canning!


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