Canning 101

Canning is one of those archetypical homesteading skills that finds itself in the mental picture we all have of the lifestyle. And this isn’t without reason; preserving food in glass jars by way of canning is an extremely useful way to make sure your valuable harvest doesn’t go to waste.

Canning isn’t without it’s down side. The energy requirements aren’t small, even when you’re just water bath canning, and canning can often be time consuming. It requires lots of glass jars and lids that are usually not reusable, and it seems like most people end up canning their surplus harvest, and thus heating up their kitchen, during some of the hotter months of the year.

Although food safety concerns with home canned goods are largely misplaced, there are rules and correct procedures that absolutely must be followed in order to safely preserve your food. This depends in part about what type of food you’re looking to preserve.

Whatever you’re canning and what method it requires, jars and the lids need to be thoroughly cleaned. Jars should be checked for any chips, particularly around the mouth. This is especially the case for jars being used multiple times, but it’s good practice to check even new jars. Jars with cracks or any chips around the mouth shouldn’t be used to can.

For “high acid” foods such as tomatoes and most fruits as well as vinegar pickles, a simple water bath canning will suffice. What this means is that the cooking and heating of the jars of food is done in a large pot of boiling water that completely submerges the jars and boils them for a specified amount of time (dictated by the recipe).

Low acid foods, such as meats and a lot of vegetables, as well as foods that are just fairly dense, require higher temperatures to safely store. This is because of the botulism microbe Clostridium botulinum, which creates the botulism toxin that makes people ill, often fatally. The bacteria can’t reproduce in high acid foods, but does so readily in low acid foods.

Pressure canning is the process of canning goods in a specialized pressurized container in order to get the food up to a temperature higher than boiling water normally reaches. Cl. botulinum is killed at 121°C/250°F.

Good pressure canners will have pressure gauges on them, as well as some backup safety mechanism. Pressure canners and pressure cookers without emergency pressure releases can be dangerous, and can essentially become a bomb and spray your kitchen with shrapnel.

They all also have a weight that goes over a vent; this is what controls the pressure that builds up inside.

Whichever canning method you’re using, proper inspection and preparation of the jars and lids is paramount. Canning jars need to be inspected for any cracks or chips, particularly if they’ve been used before. Lids and jars need to be clean, and particular attention must go to the rim of the jar and the edges of the lids. After filling the jars with food (I recommend a cheap canning funnel) and making sure that there aren’t any air bubbles left, also make sure no bits of food remain on the rim or kid of each jar. If there was, it could cause the lid not seal properly.

Something worth mentioning is that most of the lids you see are intended for one time use. I’m sure some people have reused ones that didn’t get deformed when the jar is finally used, but I wouldn’t risk it. There are also reusable lids that are available that are polymer or silicon of some sort, with a separate rubber seal. They can use the same rings to keep them on during the canning process.

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