Submitted to: Postharvest International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 25, 2005
Publication Date: N/A
Interpretive Summary: There are problems with tomato flavor due to breeding for disease resistance, yield, size, color and other horticultural traits, however, little selection is done for flavor due to lack of information. This has resulted in poor flavor quality in currently available tomato varieties in Florida, the main supplier of fresh tomatoes in the US. As a result, the US fresh tomato market has lost market share to greenhouse grown tomatoes from Canada and vine-ripe hybrid tomatoes from Mexico. The purpose of this study is to provide breeders and molecular biologists with flavor targets, specifically desirable and undesirable aroma compounds, that can be emphasized or de-emphasized in breeding selections or genetic manipulations on the molecular level. Fresh tomato homogenate headspace was sampled by gas chromatography (GC) and simultaneously sampled through a sniff port so that each aroma compound coming through the GC was smelled by a human subject, and descriptors for aroma recorded. Food grade compounds were also spiked into deodorized tomato homogenate, which was then sampled by a panel whose members generated descriptors for taste and smell. This information was used to determine desirable and undesirable flavor notes that would contribute to development of high flavored, premium tomato varieties.
Technical Abstract: The contribution of volatiles to tomato (Lycoperscon esculentum Mill.) flavor is little understood. Coarsely chopped deodorized tomato puree was spiked with one or three levels of individual food grade volatiles, reported to contribute to tomato flavor, and presented to a trained descriptive panel for flavor analysis. Fresh tomato homogenate was also analyzed by gas chromatography/olfactometry (GCO) and an aromagram generated. Based on descriptors resulting from the aromagram, past experienced consumer panel screening and trained panel rating of these individual aroma compounds, volatiles were then grouped based on similarities of descriptors into 'green', 'earthy' and 'fruity' mixtures, again added to bland homogenate at three different levels and presented to a trained panel. Six to eight panelists rated 5 aroma, 8 taste, and 3 after-taste descriptors on a 15 cm unstructured line scale and data are an average of two panels. The 'green' mix enhanced overall and green aromas while decreasing perception of tropical taste. The 'earthy' mix enhanced perception of vine and earthy aromas, and sweet taste, while negatively impacting sour and ripe tomato taste. The 'fruity' mix enhanced overall, sweet tomato, and tropical aromas as well as sweet, tropical and fruity tastes. This mix also negatively impacted perception of green and musty aromas as well as sour taste. Principal component analysis (PCA) was performed on means across panelists. Three factors were extracted explaining about 50% of the variation. Spiking with 2-isobutylthiazole, 'earthy' mixes, 1-penten-3-one and 'green' mixes resulted in drivers for high loading on the earthy and green descriptors. The 'fruity' mixes, furaneol and 2-phenylethanol were drivers for high loading on sweet and floral aroma.