Canning, Japanese style

As many of you know, home canning is pretty established in America, we have jars with a flat lid that is held down by a removable rim. Here in Japan, we have jars that have full lids, they seem to work okay, but they always make me a bit worried when I am canning, as it is not as easy to check the seals with these jars.

I would like to take a moment to explain how to can using the water bath method. You should follow these instructions closely, as there are other ways to seal jars, but they are not recommended.

Before using your jars, sterilized them by boiling for 10 minutes.

You wants to get your lids ready at the same time. I like to have them sitting in boiling water waiting for me.

Take out the jars, fill with whatever you are canning leaving 1/4 inch headroom, bubble the jars, wipe the rims, dry the lids and screw them on snugly. You don't want to make the lids too tight, or the hot air won't be able to escape.

Boil the jars for the time required by the recipe.

The jars should be completely covered by water, with the water covering two inches above the top of the jar. This will heat the air in the jar, and it will be forced out, helping to create the seal.


Take your jars out and let them cool on the counter on a towel, its better not to put the glass onto a cold surface as it might cause the jar to crack.

Here are a couple questions you might have about this process:

What is Bubbling the jars?
You may have noticed that I say bubble the jars. This means using a chopstick, or a plastic spatula to get ride of the air bubbles in the jar. You can also give the jar a bit of a bang on the counter to try and knock them loose. If you don't bubble your jar they may not seal well. As I said, the seal works by heating the air and pushing it out of the jar. If you have too much air, it won't seal well.

What is Headroom? This is the amount of space you need to leave between the top of your food, and the lid. If there is too much, or not enough space, you jar won't seal well.

Why is this important? The main reason we boil the jars to seal them, rather than using one of the other possible methods, is to help kill the bacteria that lives naturally in all produce.

What can I can? There are many things you can can, but remember, only use fully tested recipes. The reason we can can pickles is because the vinegar is highly acidic, the reason we can can jams and jellies is because the sugar acts as a preservative. Remember, never can meats or fruits and veggies that are low in acid unless you are using a tried and true recipe.

How bad can it get? You could die. If you properly process your jars, there is very little chance of danger. However, if you don't work hard to ensure everything is sterilized and sealed correctly, there is a chance of bacterial growth. Many kinds of bacteria are visible. Unfortunately, one of the most deadly, is not. That is the bacteria responsible for botulism. The bacteria that causes this isn't visible, and leaves no noticeable trace. It is actually the dead cells that are poisonous. So if you see something growing in your jars. Throw them away. Even if it looks like a simple mold you could scrap off the top don't. Trash it. Remember though, even if your jars don't seal well you can still eat them right away if you put them in the fridge.

But don't worry too much, and enjoy canning!