Jams were developed in ancient times as a means of preserving fruits that would otherwise quickly spoil. When preserved, fruits resist spoilage because they lack the water that microorganisms need in order to grow. Surface moulds can be prevented by sealing homemade preserves with an airtight layer of paraffin. Fruits boiled in sugar will gel via the interaction of fruit acids and pectin, a soluble fibre that is drawn out of the fruit cell walls by cooking. Apples, grapes and most berries contain enough natural pectin; other fruits, such as apricots and peaches, need to have it added. Low-calorie, reduced-sugar jams are gelled with a special pectin that sets at lower acidity and with less sugar. These products are often sweetened with concentrated fruit juice and thickened with starches. For nutritional value, there’s no comparison between jams and fresh fruits, because most of the vitamin C and other nutrients in fruits are destroyed by intense cooking. While fruit preserves contain substantial amounts of pectin — a soluble fibre that helps control blood cholesterol levels — this benefit is offset by their high sugar content. Simple sugars, however, make jams a source of quick energy. Fruit preserves are preparations of fruits, vegetables and sugar, often canned or sealed for long-term storage. Many varieties of fruit preserves are made globally, including sweet fruit preserves, such as strawberry or apricot, as well as savoury preserves of vegetables, such as tomatoes or squash. The ingredients used and how they are prepared determine the type of preserves; jams, jellies, and marmalades are all examples of different styles of fruit preserves that vary based upon the fruit used. In English the world over the plural form “preserves” is used to describe all types of jams and jellies. Jams and jellies are best served with cakes, pastries and tea.