There are many different jellied products but the processing steps are similar. In the past a fruit was selected, sugar was added and the mixture was boiled until it thickened enough to become a jellied product. This traditional process of manufacturing jams at home has not changed much but the availability of pectin has introduced different methods of making jellied products. They can be made faster, more economically, with a lighter color, using a softer texture and with little or no sugar. Traditionally made products cannot be made with little sugar or no sugar, but the modified pectin makes it easy today. Products made in this way are extremely attractive to those on a low calorie diet or others who have to stay away from sugar.
Jam is a thick spread made from small fruits or fruit pieces. Its gel is firm enough to hold the contents together but not strong enough to retain the shape of the container when removed. According to US standards, jelly must not contain less than 45 parts by weight of fruit juice to each 55 parts by weight of sugar. The difference between jam and jelly is that in a jelly fruit juice is used rather than the fruit itself. Both jam and jelly are concentrated to not less than 65% solid.
Jelly is made from strained fruit juice and its clarity and sparkle determine its quality. Its gel is strong enough to hold the shape of the jar when removed. According to US standards jelly must contain not less than 45 parts by weight of fruit juice to each 55 parts by weight of sugar. The finished soluble solid contents of a jelly should not be less than 65%.
Marmalade is a soft jelly which incorporates small fruits or pieces of fruits inside. Marmalades often contain pieces of citrus fruits inside, especially orange. Marmalade is made from fruit juice, peel and sugar. It displays a similar texture to a jam, except for the use of sliced peel.
Preserves are small fruits or pieces of fruits in a soft jelly (syrup). The syrup is a mixture of water and sugar. Acidic fruits are combined with heavier syrup (more sugar in water), and sweet fruits require a lighter syrup. A preserve does not hold its shape when removed from the jar.
Conserves are jams made from more than one fruit and may contain raisins, nuts, or coconut.
Fruit butters, such as apple butter, are made by cooking fruit pulp and sugar until thick. Fruit butter is the smooth, semisolid mixture containing at least 5 parts by weight of fruit to each 2 parts of sugar.
Fruit leathers, also known as fruit roll ups are very popular with a younger crowd. They are made by drying a very thin layer of fruit puree to produce a soft product with a texture similar to soft leather.