The wrinkle test is often referred to in jam making recipes, but can be difficult to actually visualise unless shown.

Generally, after adding sugar to stewed fruit, the jam is boiled vigorously until it has reduced (water has evaporated) enough to set when cool, a point known as the setting point.

The wrinkle test is a way of checking if jam has reached setting point and is therefore ready to pot in jars.

The process is quite simple, while making the jam place a saucer or small plate in the freezer. To test for setting point remove the chilled plate and spoon a small amount of jam onto it, then after it has cooled for a minute, push your finger through it.

If wrinkles are formed on the surface of the jam then setting point has been reached and the jam can be potted up in sterilised jars.