Sweetness doesn't just come from sugar -- there are hundreds of organic, synthetic, and inorganic compounds that taste sweet. Many plants contain sugar derivatives known as glycosides. Stevia, for example, is a plant high in glycosides that has been used for centuries to sweeten foods and drinks.
The degree of sweetness we taste depends on how well the receptors in our tongue interact with the molecules. The stronger the interaction, the sweeter we perceive the taste. (Check out this animation to learn more about how taste buds work.)
Taste scientists at a company called Senomyx have identified the taste bud receptor that is responsible for finding what we consider "sweet." Sugar and artificial sweeteners bind to this receptor, creating the sweet sensation that we get when we eat them. The receptors are found on the surfaces of cells all over the tongue and inside the mouth. They send messages to the brain to tell it that we're eating something sweet.
Artificial sweeteners are compounds that have been found to elicit the same (or a similar) "sweet" flavor we get from sugars. Some are low-calorie because they so much sweeter than sugar that only a tiny amount is needed. Others are low-calorie (or no calorie) because our bodies can't metabolize them. They simply pass through our digestive system without being absorbed.
Next, we'll learn about the history and use of artificial sweeteners.