Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2015
Publication Date: 9/22/2015
Citation: Baldwin, E.A., Scott, J.W., Bai, J. 2015. Sensory and chemical flavor analyses of tomato genotypes grown in Florida during three different growing seasons in multiple years. Journal of the American Society for Horticultural Science. 140(5):490-503.
Interpretive Summary: Dissatisfaction with the flavor of commercial tomato varieties has been documented and is still the subject of much attention. In this study 38 tomato genotypes from commercial and breeder lines were evaluated for sugars and acids aroma volatiles over multiple seasons and years, first to better determine their importance under diverse environmental conditions; second, to determine chemical differences between two genotypes perceived to have large differences in overall flavor in order to determine desirable flavor chemicals and their levels; and finally to gain insights into tomato flavor in general, and how we perceive it. The data from this study, especially on the complex aroma volatile component, should add to our understanding of tomato flavor and provide a possible model for breeders in selection of flavor quality.
Technical Abstract: Thirty-eight tomato genotypes were analyzed for sensory attributes “sweet”, “sour” and “overall flavor” over seven years, one to three seasons per year (March, June and December) as well as for physical and chemical flavor-related attributes including color, sugars, acids and aroma volatiles (6-7 years). Principal Component Analysis (PCA) of the data of nine genotypes showed that for harvest season, December-harvested fruit were generally associated with more acids and sourness perception and less sugars and sweetness perception and, therefore, lower overall flavor ratings compared to June-harvested fruit. March-harvested samples were intermediate. Despite the seasonal variations, there were significant differences between genotypes for sensory perception of sweetness, sourness and flavor; between seasons for sourness and flavor; and between years for flavor, with some interactions between genotypes, seasons and years. In addition to sugar and acid measurements, 29 aroma volatiles (acetaldehyde, hexanal, trans-2-pentenal, cis-3-hexanal, trans-2-hexenal, 2+3-methylbutanal, trans-2-heptenal, phenylacetaldehyde, methional, benzaldehyde, citral, trans-2, trans-4-decadienal, acetone, 1-penten-3-one, 1-octen-3-one, 6-methyl-5-hepten-2-one, ß-damascenone, geranylacetone, ß-ionone, furanone, methanol, ethanol, 2+3-methylbutanol, cis-3-hexenol, 2-isobutylthiazole, linalool, 2-phenylethanol, methylsalicylate and 1-nitro-2-phenylethane) were evaluated in 33 genotypes over the seasons. Eleven volatiles were found to positively correlate with flavor perception and 13 enhanced flavor along with the SS/TA ratio in a two-predictor model, providing aroma targets for breeders. Among the genotypes evaluated most frequently were the Florida industry standard ‘Florida 47’ and University of Florida hybrid ‘Fla. 8153’ which was released in 2006 and is now marketed as Tasti-Lee ®. ‘Florida 47’ was almost always rated lower for “sweet” and “overall flavor” compared to ‘Fla. 8153’. On a 1-9 hedonic scale, where 1 was least sweet, sour or flavorful and 9 was most sweet, sour or flavorful, average scores over the seven years were 3.8 and 5.1 for “sweet” and 4.1 and 5.7 for “overall flavor” for ‘Florida 47’ and ‘Fla. 8153’, respectively. Other genotypes related to ‘Fla. 8153’, including its parents, were also rated high for “sweet” and “overall flavor” compared to ‘Florida 47’ and other commercial varieties grown in Florida. Correspondingly, sugar measurements were higher, while acid measurements were slightly lower for ‘Fla. 8153’ compared to ‘Florida 47’. Thirteen out of 29 aroma compounds showed differences between these two genotypes, with 8 being higher in ‘Fla. 8153’ (including many fruity/floral notes) and 4 higher in Florida 47 (C-5 and C-6 aldehydes and alcohols giving green notes). This provides a useful chemical model for two genotypes that differ in flavor quality that can be exploited by breeders seeking to improve flavor.