Sweet and Salty, what are our taste buds telling us?
Flavor—encompassing both aroma and taste—provides the defining characteristic of how we experience food. Flavor has long been an enigma to scientists: Aristotle described two categories of taste, sweet and bitter. Today we recognize five basic tastes in food: sweetness, saltiness, sourness, bitterness and umami (savory). But what are the scientific components of flavor, and how can flavor be studied, quantified and replicated?
Flavor is caused by receptors in the mouth and nose detecting chemicals found within food. These receptors respond by producing signals that are interpreted by the brain as sensations of taste and aroma. Certain taste and aroma combinations are characteristic of particular foods.
For example, a green apple tastes the way it does because the unique combination of chemicals found naturally within it are perceived by our mouths, noses and brains as the distinct blend of sweet and sour tastes and volatile aromas characteristic to the fruit. Identifying this chemical profile allows food producers to retain flavor in preserved green apples and, through synthesis of these flavor compounds, makes possible the production of candy, soda and other products using artificial green apple flavor.
However, even in understanding that, the chemicals that produce flavors are notoriously difficult to study because a single natural flavor may contain hundreds or even thousands of component substances, and some of these substances are present in minute quantities. For example, one of the nine key aroma compounds found in pineapple is so potent that human subjects can detect it at only 6 parts per trillion—the equivalent of a few grains of sugar in an Olympic-size swimming pool. Understanding the components of flavor has become more important than ever with the modernization of food systems and the increased reliance on processed foods.
“The perfume of a rose, the tang of an ocean breeze, the aroma of a sizzling steak—tastes and smells, two of our senses by which we characterize the world around us. And yet, we can not adequately express, define, or explain our taste and smell sensations. We can record the sounds we hear, we can photograph the sights we see, but we cannot store and retrieve the flavor of a food or the scent of a flower except in and from our mind.”
— Irwin Hornstein and Roy Teranishi, USDA ~ The Chemistry of Flavor, a C&EN feature, 1967.