Agriculture Reference
In-Depth Information
But a high concentration of a compound does not necessarily mean that it is the most
important element. Some chemicals found in tomato flavor are more distinctive than oth-
ers, even though they may be found at far lower concentrations. Methyl salicylate, for ex-
ample, makes the distinctive smell of wintergreen. Linalool is a sweet, floral scent found
in coriander seed and oranges. Safrole - found in wintergreen, anise, vanilla and camphor
- is often described as smelling like root beer. In fact, it was used as a chemical flavoring
for the drink until it was found to be mildly carcinogenic.
Chemicals are perceived in different ways as well. There are "top note" flavors, which
tend to be heat volatile, meaning they are released just from the warmth of your mouth
and are immediately identifiable. And there are "bottom note" flavors, which are not so
volatile and linger in the background. And you wondered why there is no such thing as a
good artificial tomato flavoring?
All this chemical name-dropping is of more than academic interest. To get a handle on
the problem of tomato flavor, scientists need to be able to quantify just what it is made of,
where it comes from and how it can be measured. This is far more complicated than you
might think. To begin with, the chemical nature of flavor is not static. The flavor com-
pounds that are present in a whole tomato change when the cell structure of that tomato is
altered.
Slice a tomato, and chemicals combine and react. Chew it, and the same thing happens.
Even more elusive: when you eat a tomato, some flavor compounds are formed by the
interaction of the tomato's chemicals and your own - those enzymes found in saliva, for
example.
The fruit is constantly changing, too. It doesn't take slicing or chewing to start the fla-
vor reactions. Cell walls soften during ripening, which allows the exchange and combin-
ation of chemicals. This process, in particular, is the key to much of what we regard as
fine tomato flavor. As tomatoes ripen, all sorts of flavor-building events occur. The first
and most obvious is that the color changes from dark green to brilliant red (well, in most
cases). This is not simply a matter of decoration. That color change is caused by the devel-
opment of coloring chemicals called carotenoids. And unlike some other pigments, these
have flavor-causing chemicals attached to them.
At the same time, as the tomato ripens, the amount of sugars builds, and their compos-
ition changes. Green tomatoes don't have much sugar, and what is there is mostly glucose.
As the fruit ripens, the sugars that develop are much more heavily weighted to fructose,
which is three times sweeter than glucose. The acids in the tomato change as well, from
