Why my homemade grape jelly set?

There are a few reasons why your homemade grape jelly might not have set.

* Insufficient sugar. Sugar is essential for the gelation of jelly. If you didn't use enough sugar, the jelly will not set properly.

* Overcooking. Overcooking the jelly can cause it to lose its pectin, which is also necessary for gelation.

* Using underripe grapes. Underripe grapes contain less pectin than ripe grapes, so they are not as suitable for making jelly.

* Not adding enough lemon juice. Lemon juice helps to lower the pH of the jelly, which helps to activate the pectin. If you didn't add enough lemon juice, the jelly will not set properly.

* Using a dirty jar. A dirty jar can contain bacteria that can prevent the jelly from setting. Make sure to sterilize the jar before filling it with jelly.

If you followed all of these instructions and your jelly still didn't set, you may need to try a different recipe. There are many different recipes for grape jelly available, so you may need to experiment to find one that works for you.