Knowing When to Stop the Boil to Create the Perfect Jelly
When cooking down the ingredients to make jelly, the hardest part of ensuring your ingredients cool to a nice jell is knowing when to remove them from heat. If you get it right, you'll wind up with a batch of delicious preserves for your family, but if you get it wrong, you'll end up with a mixture that's more like syrup or candy.
In theory, you can use a candy thermometer to check when the jelly's temperature reaches 220 F (at sea level), but that's not always the most reliable way to ensure your jelly is ready to cool.
Fortunately, there are other methods for testing jelly. Descriptions of how to do a jelly "sheet test," "spoon test," or "wrinkle test" can seem mysterious if you don't know exactly what you're looking for. Let's demystify those methods so that you can make jelly with confidence.
The Early Stage of Making Jelly
During the early stage of cooking jelly, the liquid is visible while it boils. It's nowhere near ready yet. You'll need to let the liquid boil until it becomes one gelatinous liquid with no separate liquid visible boiling to the surface.
Once you've established that the liquid is condensed into one form, then (and only then) you should apply the sheet or spoon test, but the temperature of the liquid is likely to be below 220 F at this point in the process.
The Sheet or Spoon Test
When you're satisfied with the consistency of your jelly, dip a large spoon into the boiling pot and lift it about 18 inches above the pot to pour the liquid jelly out all at once. What you're looking for is the very last bit of jelly to come off the spoon. During the early stage of cooking, the last bit will pour off in a single drop.
When the Jelly Foams Up It's Almost Ready
As it gets near the gel point, bubbles will cover the entire surface of the boiling jelly and start to climb up the sides of the pot. This is when you know your ingredients have condensed into one liquid form and are just about ready to set. Temperatures inside the liquid should be in the 220 F range no matter where you stick the candy thermometer.
Do Another Spoon Test
When the jelly is almost done, the last bit of liquid jelly will come off the spoon in two drops rather than one. This means that the jelly has already begun to form into a new jellylike compound and should theoretically be ready to take off the heat and let cool in your jelly molds. Still, you should apply the sheet test to make sure it's fully ready.
Test the Jelly Until It Sheets off the Spoon
When the jelly is ready, the last drops pouring off the spoon will run together and "sheet" off the spoon. What you want to look for at this stage is the absence of large droplets replaced by these amorphous globs instead. Once the liquid no longer pours off in drops but slides off in sheets, you're ready to apply the final test: the wrinkle test.
The Wrinkle Test for Jelly
In order to apply the wrinkle test, have a small plate in the freezer while you are cooking the jelly. When you think it is done (based on the spoon test or temperature), place a small amount of jelly on the plate and return the plate to the freezer for a minute. If the jelly wrinkles when you push it with your finger, it is done.