Multiple evaluation of flavor and texture in tomatoes produced under long-term hydroponic culture that identifies the differences among cultivars and harvest periods

Although the needs for objective evaluation of flavor and texture of high-quality fresh tomato in Japanese cultivars are increasing, methods have not yet been established. To develop evaluation methods for internal quality of fresh tomato, multiple evaluations of different varieties of tomatoes harvested at different periods were conducted. Three representative Japanese and two representative Dutch tomato cultivars were grown using long-term hydroponic culture, and tomato fruits harvested in three different periods were examined for their contents of major taste compounds, mechanical properties, and sensory evaluation. As a result, differences in the content of major taste compounds among cultivars and harvest periods were observed. Some mechanical parameters correlated with texture property in sensory evaluation were found to be obtained by penetration tests from the inner to outer pericarp. It is presumed that the average force of penetration into the mesocarp represents firmness of the flesh, and a value that subtracts the average force of penetration into the mesocarp from rupture force of the exocarp represents skin awareness during eating. The sensory profile containing 19 attributes (six for aroma, two for flavor, four for taste, six for texture, and one for after-mouthfeel) of each tomato sample was also obtained. Principal component analysis characterized the sensory attributes of the samples on axes of "sweetness and perceived ripeness" and "rich flavor", which defined the potential values of fresh tomato qualities. These results show that the evaluation methods developed in this study can objectively demonstrate internal qualities of fresh tomato fruits in various cultivars harvested in different periods.