How to Avoid Air Bubbles When Canning

If you are just starting to learn the basics of canning your own food, you may be wondering what you can do to avoid or prevent air bubbles, and what it means when after processing you see bubbles in your food.

Now, some foods, such as fruits, jams, and jellies are especially prone to air bubbles, simply because when cooked the sugars in these foods may cause oxidization and the air gets trapped.

In most cases, air bubbles are not a serious cause for concern, but it is important to learn how to avoid them and can properly, because sometimes air bubbles can mean that the item did not seal properly or when you go to can in the future making the same mistakes it could lead to wasting your time and effort!

So, here are our top tips for avoiding air bubbles when canning.

1. Always Leave The Right Amount of Headspace: Headspace refers to the amount of empty room at the top of the jar after you have filled the jar with your items. If you need to, get a ruler! If the headspace is too much or too little, what happens is the air is unable to escape the way it should to create a vacuum seal.

2. Get Rid of Bubbles BEFORE Processing: There are a number of excellent tools to do this, such as the Norpro Canning Bubble Popper & Measurer which you can get for $6 if you do not already have one. Others may use a chopstick or plastic spatula or other type of object for stirring the jars and making sure all air pockets are out of the middle. (Never use metal items when stirring jars – it can cause scratches that will weaken your jars!) It can be hard your first few tries (if you do not have someone showing you the proper way) – and just because you don’t see air bubbles does that mean they don’t exist! When removing air bubbles with your spatula, make sure that you go down the sides of the jars and then push towards the middle to help force the air bubbles out of the center but make sure not to create any new ones while doing it. Sometimes tapping the jar against a thick padded towel on a counter top can help remove bubbles as well.

3. Hot VS. Cold Pack: Packing foods hot can help reduce the air bubbles, as it has not had time to cool off and then heat back up which can cause oxidization and released air. You know how fruit turns brown if you let it sit too long? Air bubbles while processing is a similar effect basically that happens inside the jars. If a recipe states cold pack or hot pack, there is likely a reason for it, so be sure to follow the recipe unless you have reason to believe it is not from a trusted source.

4. Test Acidic Content: Fruits are generally acidic, as are most pickled items made with vinegar. However, sometimes if you are making your own variation or experimenting with something new or using less/more of something, the acidic levels can change. Using Ph testing strips or a Ph Meter can help you ensure that your foods have the proper acidic content if you will be water bath canning. (Remember: meats and vegetables should always be processed in a pressure canner!)

5. Boil Longer: Remember that processing times vary with altitude and if water bath canning what appears to be boiling may not actually be boiling. Always double check your cooking times for your altitude!

What to Do When You Have Air Bubbles While Canning

If you’ve canned something and have bubbles, the important thing is to check the seal. A proper seal will be concave and have a nice ring to it if you tap it. You will be able to take the rings off and hold the jar by the lid without it falling off or slipping (be sure that if you do this test to make sure that something soft below it so it will not shatter or break!).

If the item is properly sealed, most likely you have nothing to worry about. If the seal is not good, then you will want to either reprocess again in clean jars and new lids, or you may decide to freeze the items instead if it is not something you can eat right away.

Have any tips for avoiding air bubbles while canning that we might have missed? How do you check to make sure your items are properly canned? Share them in the comments section below!