The most common ingredients in soft drinks are carbonated water, which provides the bubbles, and some sort of sweetener. In colas, caffeine is the principle addition, adding the stimulant. While colas are the most common form, soft drink companies have developed highly diverse flavor options, as well as varieties that substitute for at least one main ingredient, such as with diet sodas.
Originally, colas used extracts from both the coca leaf and the coca nut in combination with sugar water for their recipes, the coca leaf being the item from which cocaine is derived. Nowadays, cola manufacturers use only the nut, the major active components of which are caffeine and theobromine. Most modern soft drinks no longer use plain sugar, but a substitute called high fructose corn syrup. However, diet varieties typically use either aspartame, saccharin or sucralose instead.
Most soft drink producers prefer a finished product exhibiting some bite, which adds a cleansing aspect to the taste. This commonly involves an acid, such as phosphoric or citric, the latter being especially applicable to lemon-lime varieties. To enhance shelf life and prevent development of bacteria, molds and yeast, preservatives such as sodium benzoate and potassium sorbate are common to soft drink recipes. Red dye 40 is frequently used to color orange-flavored varieties.