PECTIN
Rhubarb is low in pectin, jam may not set
Pectin should be added to jam at the beginning of the cooking process to help the jam set properly.
Yes, tartaric acid helps jam set by interacting with pectin and promoting gel formation. It enhances the thickening process, resulting in a firmer texture for the jam.
Reducing sugars in jam has two functions. The first function is that it helps the jam set and acts as a preservative.
A set
The usage label tells you when the jam is set to expire or be not as good to eat. It's informal or slang
Jam is a solid because it holds its shape outside of the container. if it is not set up properly, it could be a liquid.
sur-gel is a brand name. Pectin is the ingredient. Pectin is the ingredient used in jam making, it helps set the jam.
If the jam is not setting properly try adding the juice of a lemon and boiling it all up again for five minutes and then re-testing the set. it You can do this by putting a spoonful or so of the jam onto a very cold plate (taken from freezer). put it back into the freezer for 10 mins. Take it out and push the surface of the jam gently with your finger -- if you see the surface wrinkling up, the jam should set and can be put into jars.
To make blueberry jam without using pectin, you can cook the blueberries with sugar and lemon juice until the mixture thickens naturally. The natural pectin in the fruit will help the jam set.
you have to jump and then set a traffic jam!