Preventing Crystal Formation when Making Jam and Jelly

Following proper procedure is critical to prevent jam or jelly from becoming grainy. This video describes causes as well as tips to prevent crystal formation.
Preventing Crystal Formation when Making Jam and Jelly - Videos


Crystal formation in jam and jelly can occur for a number of reasons. Good procedure as discussed in the video will help prevent this from occurring.


Food Preservation

More by Martha Zepp 

View Transcript


- So Martha, sometimes my jelly is grainy.

Other times, I have hard pieces of white substance in my jelly, particularly after it's been opened a while.

What are these?

- Boy, that is a great example of crystallization.

These are sugar crystals.

You're familiar with crystals as you see them when you measure a cup of sugar.

You can identify the individual crystals as you're measuring that sugar, to put it into the fruit to cook the jelly.

What you don't want is to find the crystals after the jelly is made.

- So Martha, what causes crystals to form in my jelly?

- Crystals can form as a result of excess sugar, undissolved sugar during cooking, or over or under cooking.

Another source of crystals in grape jelly is tartrate crystals.

Jelly that crystallizes in the refrigerator can be another problem.

Let's look at each situation.

Excess sugar may increase the concentration beyond what the liquid or the fruit can hold.

Use a research tested recipe, and measure the ingredients precisely.

Research tested recipes such as from "So Easy to Preserve," or from our "Let's Preserve Jellies and Jams." Use the dry measuring cups to measure the sugar, and level it with a knife.

While the jelly cooks, sugar crystals may form about the edge of the boiling mixture.

These can serve as seeds for crystallization.

If necessary, wipe the side of the pan with a damp cloth before filling the jars.

There's a couple of things you could do, you can take a paper towel and wipe the edge, just be very careful that you don't burn yourself when you're doing that.

You can wet a pastry brush, but make sure that it's not going to melt.

This is a silicon pastry brush, if you had a natural fiber that would work, and you can sort of wash the crystals down.

And before I fill the jars, I find taking the silicon scraper also helps to remove some of the crystals.

Commercially jellied products often contain corn syrup, which serves as an interfering agent to prevent crystallization.

Only use corn syrup in recipes calling for it.

Crystals form when the mixture is cooked too slowly, or too long.

Cook jelly at a rapid boil.

Cook until the sugar has completely dissolved, and is mixed with the fruit juice.

Remove from the heat immediately when the jelling point is reached on a long cooking jelly, or when the designated time is reached in a commercial pectin product recipe.

Make small batches at a time, usually five to eight cups.

Do not double recipes.

- So when I prepare grape juice for jelly, I find crystals at the bottom of the juice, even though I haven't added sugar yet.

They look different from sugar crystals.

What are they?

- Can you see the crystals in there?

- Yeah, what are they?

- They're actually tartrate crystals.

Like cream of tartar?

It's a natural component of grape juice.

What you want to do is to allow the juice to sit overnight in the refrigerator.

The crystals will settle to the bottom of the container.

Carefully pour off the juice without disturbing the crystals.

Just very carefully, pour it through a sieve that is lined with a coffee filter, or a double layer of cheesecloth, and those crystals will stay in the bottom of your container, and your strained juice will be clear.

Another time you may find crystals is after you have opened a jar of jelly, and it is stored in the refrigerator for a period of time.

If it's stored with a loose lid, the cooling process of the refrigerator may cause evaporation of the liquid.

It'll start at the top of the jar, and eventually work its way through the jelly.

Use a tight fitting lid to reduce the availability of air that can cause evaporation.

We hope this information has been useful to you, and that you will have a successful product next time.

- Thanks Martha for the information.

- You're welcome.


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