How Long does it take for Jam to Set?

Making your own jams can be a fun, exciting way to preserve the fruits that you have grown or picked throughout the harvest season, plus it gives you complete creative freedom to test out interesting flavor combinations to make something all your own.

In order to make jam, it has to be boiled first; during the boiling process, the jam is runny and doesn’t have much density to it, thus making it hard to tell to the untrained eye just what the jam setting point is. So we’ve compiled some tried-and-true expert tips that will help you determine when your jam has set.

What Makes Jam Set?

Before we dive into exploring the ways to tell that your jam has set, let’s first take a look at what makes jam set to begin with.

Making jam is a reactive process that goes far beyond just boiling your fruits and some sugar. What makes the jam set into its jiggly form is how the sugar, acidity from the fruit, and pectin combine and react to each other. Pectin is the main ingredient when it comes to making jam and what ultimately ensures that the jam sets properly, and it can be found already added into specialty jam sugars.

What causes the setting reaction is when the fruit and sugar are boiled during the cooking process, the pectin starts bonding with the ingredients, causing them to weave together to create a tight bond much like a spider’s web while the water evaporates. The acid in the fruit also plays a key role, as these acids help attract the pectin to itself, thus creating the semi-solid mass known as jam.

How to Test When Your Jam is Set

In order for your jam to reach the perfect setting point, it must first come to a rolling boil. If it doesn’t reach a rolling boil, the jam will most likely not set the way it is supposed to. A rolling boil will tell you that the much of the water contained in the fruit has evaporated, and as more water evaporates, the temperature will increase to just over 100 degrees Celsius or 212 degrees Fahrenheit.

For the perfect jam setting temperature, you’re going to look for 105 degrees Celsius or 220 degrees Fahrenheit, and it’s easy to find out the exact temperature of your jam with a jam or sugar thermometer. This type of thermometer was specially designed to test the setting point of jams and jellies.

Just stick the tip of the jam thermometer into the boiling jam mixture to get an accurate temperature reading; once it’s reached the perfect setting point, you just remove it from the heat and begin pouring the jam into jars.

However, just in case you don’t have a jam or sugar thermometer, there are other methods that can be used to check the setting point without having to use one.

• Spoon Test

To use this method, you will want to place your spoon into the refrigerator to cool it, as you need a cold spoon.

While the jam is at its rolling boil, take the cold spoon and pick some jam up onto it, then raise it up above the pan and tilt it so that the jam flows off of the side of it. If the jam runs off of the spoon smoothly like a sheet as opposed to dripping, then it has reached the ideal setting point.

• Wrinkle Test

For this test, you will need some plates or saucers that are heatproof; place them in the freezer before you begin making the jam so they reach the ideal level of cold.

Once you think the jam is ready, take out one of the plates and spoon out a little of the jam onto it, then wait for a few minutes for it to cool and give it a poke. If when you poke the jam there is any tension on the surface and it wrinkles, then you have reached the ideal setting point. However, if it’s runny the jam needs to continue to cook for another five to ten minutes before it’s tested once more.

Determining the Setting Point

Although the sugar thermometer method is best, the other methods described will work in a pinch. Part of making great jam is picking out the perfect fruit and achieving the perfect combination of pectin, acid, and sugar as well as lots of practice, so don’t become discouraged if you don’t succeed at first. Besides, any under-set jams can be used as bases for fruit sauces and syrups unless they’re burnt, so it’s not necessarily a waste if it doesn’t go right.

Pectin and Acid Chart of Fruits and Vegetables

Fruits with high pectin and acid levels should be prepared with low to medium pectin and acid ingredients to create the perfect jams. For example, to make an apricot jam, use lemon juice. A great blackberry jam is made with a combination of blackberries and apples as well as some lemon juice. Check out this chart for comprehensive acid and pectin content in many common fruits and vegetables.

Common Problems

So you’ve tried making jam, but no matter what you’ve tried to do it hasn’t set? This can be caused by a lack of pectin and acid, or maybe the water hasn’t evaporated enough, so return the jam to boiling for a few minutes then retest. Lemon juice can also be added before re-boiling to help add to the acid content.

Other common problems that can’t be re-boiled to fix them include:

• Caramelization, when the jam has darkened in colour and tastes like caramel
• The fruit becomes tough due to not being cooked enough before sugar was added
• The fruit floats to the top for the same reason or not standing long enough
• Crystallization from too much sugar not being dissolved
• Fermentation from bruised, mushy, and/or over ripe fruit