Fresh tomato flavor: Interrelationships between sensory, chemical and instrumental analyses

Tomato flavor is a complex mixture of volatile aromatic compounds and sugars and acids. There is still a lack of understanding about the interactions of volatile and non-volatile compounds in fresh tomato flavor. The breeders and molecular biologists do not have a clear target for modification of fresh tomato flavor. This project evaluated the fresh tomato flavor using trained sensory panels and selected chemical and instrumental techniques, in an effort to get a better understanding.; Twelve tomato selections were evaluated in summer 1999 for their sugars, organic acids and aromatic volatile concentrations. Sensory analysis was also performed on these selections using a trained panel. The sensory descriptors generated were regressed against the chemical and instrumental measurements to generate prediction models. These prediction models were later validated using six tomato selections in fall 1999 and four more selections in spring 2000. Studies were also conducted on the sugars, acids and aromatic volatiles of tomatoes harvested at different stages of maturity, red-ripe and breaker. Two crops grown at two different locations and in different seasons were used for this purpose. Lastly, the electronic nose was used to determine whether it could successfully classify tomatoes harvested at different maturity stages and different tomato cultivars.; Good prediction models were generated for most of the descriptors based on the coefficients of determination of regression analysis. The aromatic descriptors had good relationships with both volatile compounds and sugars and acids. Hexanal, ethanol, geranylacetone and β-ionone were some of the key volatile compounds in the prediction models. Among the non-volatile measurements, sucrose equivalents and titratable acidity were important components of the prediction models. The prediction models were later validated with tomato selections from two different seasons. The predicted values for the descriptors were generally much higher or lower for both the crops.; Tomatoes harvested at the red-ripe stage were more flavorful than breaker tomatoes. The red-ripe tomatoes had higher sugars, soluble solids and sucrose equivalents and lower organic acid content than breaker fruit. These tomatoes were also rated higher by the sensory panel for sweetness, fruitiness and tomato-like descriptors and lower for sourness, bitter and astringency. The tomatoes harvested from the different locations demonstrated different correlations with volatile and non-volatile compounds. The electronic nose was successful in classifying the breaker and red-ripe tomatoes and also separating cultivars harvested at the breaker stage. All the tomato crops had high fruit-to-fruit variations with respect to their volatile and non-volatile components.; There are various factors other than the sugars and acids and volatile compounds having an influence on fresh tomato flavor. The results from these studies provide an important first step in the development of tomatoes with improved flavor.