From MSNBC:
That fresh grassy smell wafting up from the newly sliced tomato may be its way of saying “I’m good for you.” Indeed, the odors from foods ranging from garlic and onions to ginger and strawberries may be nutritional signals that the human nose has learned to recognize. “Studies of flavor preferences and aversions suggest that flavor perception may be linked to the nutritional or health value” of foods, researchers Stephen A. Goff and Harry J. Klee report in Friday’s issue of the journal Science.Klee and Goff analyzed two types of tomato, the wild cerasiforme and the commercially grown Flora-Duke. Except for one chemical that also affects color, the sugars, organic acids and volatile compounds associated with tomato flavor were reduced in the commercial product.
For example, one of the volatile compounds associated with the “tomato” or “grassy” flavor is called cis-3-Hexenal, which is also an indicator of fatty acids that are essential to the human diet. They found that the wild tomato contained more than three times the amount of that chemical than the cultivated version.
More here.