The Chemistry of a Great Tasting Tomato

It is widely recognized that the flavor quality of many commercially produced fresh fruits has declined. We have taken a systematic approach to defining the chemical composition of a good-tasting tomato by exploiting the surprisingly large chemical variation found within the species. Tomato flavor is determined by complex interactions of a diverse set of chemicals that are sensed by the taste and olfactory systems. These chemicals include sugars (glucose and fructose), acids (citrate and malate) and a set of less well defined volatiles. We have identified the most important chemicals contributing to good flavor. Knowing how the components of tomato flavor co-vary with preference, and creating a system to ‘engineer’ these preferences constitutes a new direction in the chemistry of human flavor preferences for the tomato fruit specifically, and naturally grown food products in general. Eighty tomato varieties spanning the range of biochemical diversity were tested by consumers to generate a subjective sensory profile of perceptions, including overall liking. A total of 44 sugars, acids and volatiles were either significantly positively or negatively correlated with overall liking. Many of the positively correlated volatiles were not previously associated with tomato flavor. Conversely, several volatiles widely accepted as being important contributors to flavor did not correlate with liking. The lack of correlation for the highly abundant C6 volatiles was validated with transgenic fruits that do not synthesize these volatiles. Finally, regression analysis and reverse engineering created a model, identifying target levels of each flavor chemical that essentially define the recipe for an ideal tomato. This synthetic approach to understanding the chemistry of liking for complex natural products provides breeders with the knowledge to achieve flavor improvements. Such a synthetic approach establishes a formalized method for improving a complex natural food.