Chutneys are thick, jam like mixtures made from a variety of fruits and vegetables, spices, sugar and sometimes vinegar. Any edible sour fruit can be used as a base for chutney to complement the sweet taste from the sugar. The high sugar content has a preservative effect and vinegar is not always necessary, depending on the natural acidity and maturity of the fruits that are used. Most chutneys are boiled, which produces a caramelised syrup and alters the taste, colour and thickness of the product. Boiling also helps preserve the product through pasteurisation.