All are a mixture of fruit and sugar. The difference between jelly and jam is the amount of solid fruit in the mixture. Marmalade is made with citrus rinds. Jelly, jam and marmalade are all fruit preserves.
What is fruit preserve?
Fruit preserve is any fruit and sugar preparation meant to last for months or even years. The Greeks were preserving fruits with honey before sugar was introduced to Europe.
Recipes for fruit preserves can be found in the oldest collection of methods to survive from antiquity, De Re Coquinaria (“The Art of Cooking”) is attributed to Marcus Gavius Apicius, the famed epicure who flourished during the reign of Tiberius early in the first century AD. The recipes themselves were not compiled until late in the fourth or early in the fifth century. [Source]
The practice was developed to preserve what had been harvested during the warm months to tide people over during the winter. In the warmer regions where there are no bitterly cold winters, it was a matter of economics—preserve what couldn’t be consumed to avoid wastage.
Jams and jellies originated from the Middle East where sugar was already in widespread use long before the Europeans were introduced to it.
How is jam different from jelly?
When pieces of fruit are boiled with sugar syrup, it becomes jam. Jam has visible bits of fruit it in and it has a spreadable consistency. If the fruit is stewed in sugar uncut, the result is a compote.
If the cooked mixture is strained, the clear strained mixture is jelly. If fruit juice is cooked with sugar, the result is jelly. Jelly is more firm than jam. There are no visible bits of fruit in jelly.
Fruit jelly is NOT the same as fruit-flavored gelatin in the grocery. Gelatin comes from animal collagen.
What about marmalade? Is marmalade a jam or a jelly?
Marmalade is neither a jam nor a jelly. It is made with citrus rinds—yes the skins—and sugar.
Since jam is made with fruit and jelly is made with fruit juice, marmalade does not fit into either description. Clearly, marmalade is a fruit preserve in its own class.
Moreover, those who say that marmalade is, by definition, made with rinds of the “Seville orange” exclusively are wrong. The choice of the “Seville orange” is a British preference. Marmalade can be made with other citrus rinds, including lemon, lime and mandarin oranges, or the combined rinds of different citrus fruits.
Why is it important to know what is jam, jelly or marmalade?
They’re all fruit cooked in sugar. They all serve the same purpose—to be spread on crackers and bread. What purpose does it serve being able to tell the difference between, jam, jelly and marmalade? Well, for one, the three differ in nutritional value. Whole fruits in a jar contains more nutrients than reduced fruit juice in a jar. They also differ in flavor and texture.
Because it is the rind of the citrus that is most aromatic, marmalades may be more aromatic that jams and jellies but they are not necessarily more flavorful nor more nutritious.
Finally, there’s the matter of price. Jellies—made mostly from juices leftover from making jam—should logically be less expensive.