Spreading A Little Jam
There is some science involved in preserving a good quality jam. Typically recipes call for the flesh and juice of a single variety of fruit or vegetable and many of them have a high enough amount of natural pectin in them that packets of additional pectin are not required. Examples of these kinds of fruits include cranberries, plums, apples and blackberries. Other fruit that contain lower amounts of natural pectin can produce quality jams when combined with fruits with higher natural pectin. For example, cherries, peaches, rhubarb and strawberries can be mixed with apples to make a great jam without having to add additional pectin.
Jiggling Like A Bowl of Jelly
The juice used for jelly comes from a filtering or straining of cut, crushed, chopped and cooked down fruit. The cooking of the fruit assists with both juice and pectin extraction when filtering takes place. There are jelly bags available on the market just for this purpose and there is a very simple, yet strict, method to the straining. Typically the bag is suspended over a bowl by string with gravity doing all the work. Squeezing the bag to speed up the process is not recommended as it may force some pulp into the jelly mixture. This is not a problem for some home canners where others adhere to the requirements of their recipe to the letter. Jelly is also a bit more versatile than jam in that the spectrum is wider in what fruit or vegetables can be used which is why there are such selections a grape or apple jelly all the way to spicy jellies containing hot peppers and additional fruits and vegetables.
The Bonus Round
Now that you have a better understanding of what a jam or jelly is, do you know what marmalade is? Marmalade is a fruit spread that is produced using the juice and peel of citrus fruits. There is no chopped, cut or crushed flesh in the mixture which is boiled in water and sugar to activate natural pectin. Oranges, lemons, grapefruits and limes produce excellent marmalade as does combinations of these fruit. Again, there are some similarities to jams and jellies but this is still in a category of its own along with the difference between jam and jelly.