Did you know that pectin is a water-soluble substance that is found in the tissues of all fruits and is a natural thickening and jelling agent.Different fruit have different amounts of pectin.
Under ripe fruit contains more pectin than ripe fruit but the flavor of under ripe fruit is not as suitable for jams and soft spreads. The amount of pectin in fresh fruit varies depending on the type and variety and freshness.
How it works...and this is where we get a little geeky ;)
When pectin molecules come in contact with fruit acid, chainlike structures in the pectin become charged and they begin to fold in on themselves. These folded chains trap water from the fruit or juice and form a gel. The introduction of sugar increases the strength of pectin, allowing it to trap more water and increasing its ability to jell. This is why it is important to use the right ration of fruit, pectin, sugar and acid. Too much sugar will result in too firm a set, too little and it will be runny. Jams made without added pectin must be cooked for longer period of time and end up thickening from the evaporation of the juice rather than from the process of jelling.
Excessive heat or high heat for an extended period of time during cooking will cause the pectin to break down and prevent jelling from occurring. If the length of boiling time is not controlled you may damage the pectin and end up with a runny jam.
Commercial Pectin is not evil
It comes in 2 forms; liquid or powdered. They are NOT interchangeable. Each requires a different balance of fruit, sugar, and acid to obtain the desired set. Powdered pectin is added to the fruit BEFORE cooking, while liquid pectin is added to the heated fruit and sugar mixture near the end of the cooking process.
Both forms are 100& natural and are derived from either tart apples or the white pith found under the colored peel of citrus fruits. The pith tends to have a sour flavor and it tends to be used in marmalades.
You can make your own pectin but be aware that you may have inconsistent results as you will be unable to control the concentration of pectin. Also, home made pectin has an extremely short life span and should be used within 24 hours.
I prefer to use store bought pectin to ensure consistent results when making jam.
Canning without pectin
When making jam or jelly without adding commercial pectin, at least ¼ of the fruit must be under ripe in order for it to set. But always remember, that this high proportion of under ripe fruit can change the flavor and texture of the final product. It must also be cooked for a longer period of time.