Uh-oh, your jars leaked during processing. What do you do now, and why did it happen?
More than likely, you’ve just experienced what’s known as “siphoning.” Siphoning occurs when the contents of your newly canned jars are drawn out (or pushed out) during the sealing process.
If you ever have greasy jars after pressure canning, or if your jam and jelly jars are sticky, then siphoning is likely the culprit.
Fortunately, it’s not harmful —usually—just super annoying.
What Causes Siphoning in Canning?
Turns out, siphoning is just a “fluke” sometimes. Like a failed seal—despite your best efforts, it can happen.
Siphoning can be caused by extreme temperature variations, air bubbles, insufficient (or too much) headspace, fluctuating pressure, and the misalignment of the sun and the moon.
Okay, that last reason is a joke.
Sometimes we just don’t know why a particular batch of jars decided to act up, although it does seem more common in pressure canned food and when preserving fruit or tomatoes.
However, there are a few ways that we can minimize the risk of liquid loss.
How Do I Stop My Jars From Siphoning?
Nobody wants to lose a drop of preserved food. We don’t haul out the canner and subject ourselves to steam-induced frizzy hair for fun, right? 🙂
So, to avoid losing any of your food, here’s how to reduce the chance of siphoning when canning:
- Be sure to leave the amount of headspace specified in the recipe. Headspace is important, and the specifications are there for a reason.
- Remove air bubbles. There are tools for this, but running a rubber scraper around the inside of the jars should help break these up. While the presence of air bubbles may not contribute directly to siphoning, they do affect the amount of liquid you think is in the jar. So, get rid of them before canning just to verify you have the amount of liquid and headspace required.
- Avoid extreme temperature fluctuations. It’s a good idea to let them sit for 5-10 minutes before moving them to the counter.
- If using a pressure canner, follow the pressure recommendation in the recipe and don’t allow abrupt pressure changes. Maintain a steady rocking motion during processing. Then be patient when removing the jars. Once the pressure comes down to absolute zero, remove the weight and let the canner rest for 5-10 minutes. Then, remove the lid and wait 10 more minutes before removing the jars.
When Liquid Loss Becomes an Issue
Losing liquid in your canned food can sometimes be harmful, whether it’s due to siphoning or another reason.
It depends on the amount of liquid lost:
If the liquid in your jar drops by half or more, don’t put it on your pantry shelf. It’s not ruined, but it’s no longer safe to assume it’s shelf stable.
Instead, break the seal and put it in your refrigerator to eat within 3 days. Alternatively, you can go ahead and freeze it after breaking the seal.
Just remember, liquid loss up to 50% is still acceptable as long as the jar has sealed. When greater than 50% of liquid is lost, treat it as an unsealed jar.
