There are a number of factors which effect a food’s flavor: taste, smell, color, temperature, texture, spiciness or hotness, appearance and psychological effects. Taste is sensed by the taste buds which are found on the upper surface of the tongue. Our sense of taste acts like a signal to our bodies to take in essential nutrients. Some studies have found that different tastes are markers for underlying nutritional qualities. For example, it is believed that breast milk has a umami taste and that babies crave both sweet and umami, which is reflective of their underlying need for nutrients.
In the western part of the world we are basically familiar with four basic tastes: sweet, sour, salty and bitter. In 1908 a Japanese scientist identified a fifth taste that is found in some foods: umami. To be a “taste” there must be taste receptors (buds) that are triggered by the particular chemical compounds that makes up the taste.
There is no English word for umami. It is a savory taste created primarily by glutamate – it is subtle and blends with the other tastes to round out flavors. Most people don’t recognize umami when they eat it, but it can be detected in ripe tomatoes, Parmesan cheese, cured ham, mushrooms and some meat and fish. MSG also produces umami taste. Tomato sauces and soy sauces add umami taste to foods.
One of the keys to creating great tasting food is to combine the five tastes to create a synergistic effect. When glutamates and isosinates are combined, they have a powerful multiplier effect, which enhances the umami-ness of the underlying food.
Umami can help explain the powerful spread of the tomato from South America. In a few hundred years, it radically transformed ancient cuisines (e.g. Italy and India). The local recipes were already very attractive before the tomato, but the addition of the tomato unleashed more of the umami qualities that were already present in minute quantities in the underlying substances.
The existence of umami explains certain preferences of great chefs: young peas over older ones, ripe tomatoes over fresh ones, and aged cheeses over un-aged ones. Same with aged hams, and dry-aged beef, and sun-dried tomatoes (even when fresh ones are available.) Your palate is selecting for the more powerfully concentrated glutamates (and drying is just one way of achieving that).
Spiciness or hotness is not a taste. Again, there is no specific taste bud receptors for spiciness. Instead, spiciness is detected by a combination of normal taste reception and triggering of the nerve that is normally responsible for detecting the thermal temperature of food. Ethanol and the chemical capsaisin are the chemicals typically responsible for triggering the particular nerve. As you would guess, capsaisin is common in chili peppers.
Researchers in France claimed that there is a sixth taste – fat. They claim to have discovered taste receptors in the tongue for fat. The scientific and culinary community has yet to accept their claim of the sixth taste. Obviously, fat changes the flavor and enjoyment quality of food, but to be a taste it actually has to trigger taste bud receptors on the tongue. If fat is not a “taste” then it changes the flavor of food by affecting the texture or some other aspect of flavor.
Many thanks to JD Hilburn suggesting this IFOD ten years ago!