Since sharing my first recipe for Margarita Marmalade here on Food Fanatic, I've received a few questions about how to reach the gel stage.
The gel stage is the point at which your jam, marmalade, or other preserve sets up or gels, and becomes spreadable. To help clear things up, the Canning question I'll be addressing today is: How do I make sure that my soft spreads made without the use of commercial pectin will gel properly?
The answer is that there are three tests you can perform to ensure that your soft spreads made without the use of commercial pectin have reached the gel stage.
Note: Always remember to remove the pan you're using to cook your soft spreads from the heat first when performing these tests!
1. The Temperature Test
The first test is to cook the soft spread until it reaches a temperature of 220°F Fahrenheit, or 8°F above the boiling point of water. I use a candy thermometer like the one pictured above because I find the digital display easy to read.
No matter what type of thermometer you choose, make sure not to let it make contact with the bottom of the pan when measuring the temperature, or you will get an inaccurate reading.
Also, you may need to adjust for your altitude as well. If you are at or below 1,000 feet above sea level, water boils at 212°F...but at higher altitudes, water boils at a lower temperature, so to compensate you'll need to subtract 2°F for each added 1,000 feet. For example, at 2,000 feet above sea level, you would cook your soft spread until you reach a temperature of 216°F Fahrenheit.
In addition, atmospheric pressure may affect the set of your soft spread as well. If you're cooking jam and a storm rolls in, atmospheric pressure decreases, which also affects the boiling point for water by lowering it slightly. It may or may not have a huge effect on your spread, but it's something to have in the back of your mind if you hit a few snags achieving the set you want.
In this sense, making jam is actually quite similar to making candy. At the temperature of 220°F, two things happen: the first is that the structure of the sugar in your soft spread is altered and it bonds with the natural pectins in the fruit, which is what causes it to gel and become spreadable.
Also, the soft spread has reached a measure of physical heat such that sufficient water has cooked out, thereby increasing the ratio of sugar to water.
On a related note, if you've ever drastically reduced the amount of sugar in a recipe only to end up with a very runny or sauce-like jam, this is why: your recipe no longer contained enough sugar to effectively bond with the available pectin, causing the spread to fail to achieve a high enough temperature to reach the gel stage. (Of course, there are ways to reduce the amount of sugar in a recipe using commercial pectin, but that is a topic for another article.)
2. The Freezer Test
The second test, and the one I do most often now that I'm more familiar with how soft spreads should look when they are close to reaching the gel stage, is to chill a small plate or two in the freezer.
When you're ready to test, place a teaspoonful of your soft spread on the plate, and place it back in the freezer for a minute or so. Take the plate out and push the edge of the spread with your finger.
If the surface has formed a skin and it wrinkles when you push it, you've reached the gel stage. If it doesn't wrinkle or is still very runny, cook your soft spread a few minutes longer and try the test again.
3. The Sheet Test
The third test is to dip a cold metal spoon into the boiling jam. Quickly lift the spoon and turn it horizontally so that the soft spread runs off the edge. If it is very drippy when it falls off the spoon, cook a few minutes longer and try the test again.
You'll see that the drops will start to become heavier, and will begin to drop off the spoon two at a time. When the two large drops join together and fall off the spoon in one large "sheet" of soft spread, you've reached the gel stage.
I hope this helps! As always, if you have any canning questions, feel free to send me an e-mail or to shoot me a message on Twitter or Facebook. Happy canning!