In the United States, jam that has been filtered to remove pulp and make it clear is called jelly (and is not called jam). In the United Kingdom and elsewhere, filtered jams are still called jams, the word "jelly" usually being reserved for a sweetened gelatine dessert. (An exception is bramble jelly, a seedless blackberry jam.) Jam that has whole pieces of fruit is sometimes called preserves, or conserves if it has nuts as well. Jam with citrus fruit peel is called marmalade.



The use of cane sugar to make jam and jelly can be traced back to the 16th century when the Spanish came to the West Indies, where they preserved fruit, but the Greek technique of preseving quinces by boiling them in honey was included in the Roman cookery book associated with the name Apicius.

The proportion of sugar and fruit varies according to the type of fruit and its ripeness, but a rough starting point is equal weights of each. When the mixture reaches a temperature of 104 ?C, the acid and the pectin in the fruit react with the sugar, and the jam will set on cooling. However, most cooks work by trial and error, bringing the mixture to a "fast rolling boil", watching to see if the seething mass changes texture, and dropping tiny samples on a plate to see if they run.

How easily a jam sets depends on the pectin content of the fruit. Some fruits, such as gooseberries, redcurrants, blackcurrants, citrus fruits, apples and raspberries, set very well; others, such as strawberries and ripe blackberries, need to have pectin added. There are proprietary pectin products on the market, and most industrially-produced jams use them. Home jam-makers sometimes rely on adding a pectin-rich fruit to a poor setter; hence the popular old favourite blackberry and apple. Other tricks include extracting juice from redcurrants or gooseberries. Making jam at home used to be common, but the practice is declining, and the accessories, particularly the cellophane covers for jam jars, are becoming more difficult to find in some locations.

In the European Union, the jam directive (Council Directive 79/693/EEC, 24 July 1979) set minimum standards for the amount of "fruit" in jam, but the definition of fruit was expanded to take account of several unusual kinds of jam made in the EU. For this purpose, "fruit" is considered to include many things that are not ordinarily classified as fruits: "tomatoes, the edible parts of rhubarb stalks, carrots, sweet potatoes, cucumbers, pumpkins, melons and water-melons". This definition continues to apply in the new directive, Council Directive 2001/113/EC (20 December 2001).

Joan Mir? used blackberry jam as an art medium.