People often ask one of two questions (but rarely both) related to this topic:
- What is syphoning?
- Why are my preserves missing liquid after a water bath (i.e. boiling the jars with fruit in them)?
There are a few reasons that jars will lose liquid during canning, including:
- An illusion. Jars can seem to have lost liquid during canning when in fact they haven’t lost any liquid at all. Air bubbles trapped under fruit or pickles work their way to the top of a jar during the water bath and increase the headspace in the jar.
- A small crack. This is not common (although it happens) – cracks usually lead to breakage.
- Dirty rims. A small amount of spice or fruit/ vegetable on the rim can allow liquid to sneak out during processing.
But there’s another, less obvious reason called syphoning.
Syphoning is common in preserves using thin liquids such as brines or syrups. If you remove your jars from the canner immediately after your timer rings, you may run into syphoning. As the jar is removed from the boiling water the rapid cooling creates pressure on the content which helps force the air out of the jar and ‘pop’ the lid shut. If the cooling is too rapid you will find that the escaping air syphons some of the content of your jar.
Evidence of syphoning includes jars missing liquid and your counter/ cutting board being covered in brine or syrup. This is especially common with pressure canning.
To avoid syphoning, remove your canner (or turn off the heat) for a few minutes before removing the jars from the water bath. This will allow them to cool a bit before being pulled out of the waterbath and will reduce or eliminate syphoning.
Have you ever run in to this?