There are five known fundamental tastes in the human palate: salty, sweet, sour, bitter, and umami. Umami is the proteiny, full-bodied taste of chicken soup, or cured meat, or fish stock, or aged cheese, or mother's milk, or soy sauce, or mushrooms, or seaweed, or cooked tomato. "Umami adds body," Gary Beauchamp, who heads the Monell Chemical Senses Center, in Philadelphia, says. "If you add it to a soup, it makes the soup seem like it's thickerit gives it sensory heft. It turns a soup from salt water into a food." When Heinz moved to ripe tomatoes and increased the percentage of tomato solids, he made ketchup, first and foremost, a potent source of umami. Then he dramatically increased the concentration of vinegar, so that his ketchup had twice the acidity of most other ketchups; now ketchup was sour, another of the fundamental tastes. The post-benzoate ketchups also doubled the concentration of sugarso now ketchup was also sweetand all along ketchup had been salty and bitter. These are not trivial issues. Give a baby soup, and then soup with MSG (an amino-acid salt that is pure umami), and the baby will go back for the MSG soup every time, the same way a baby will always prefer water with sugar to water alone. Salt and sugar and umami are primal signals about the food we are eatingabout how dense it is in calories, for example, or, in the case of umami, about the presence of proteins and amino acids. What Heinz had done was come up with a condiment that pushed all five of these primal buttons. The taste of Heinz's ketchup began at the tip of the tongue, where our receptors for sweet and salty first appear, moved along the sides, where sour notes seem the strongest, then hit the back of the tongue, for umami and bitter, in one long crescendo. How many things in the supermarket run the sensory spectrum like this?
