The study – published in Current Biology – investigated the chemistry behind tomato flavours by analysing the chemical profiles of 278 tomato samples representing 152 varieties of tomato.
Led by Harry Klee of the University of Florida, the researchers set out to define the chemicals that are most important to consumer appreciation for one particular tomato or another – finding that large variations of volatile flavour compounds and flavour-associated sugars between different varieties hold the key flavour.
"We now know exactly what we need to do to fix the broken tomato," said Klee, who added that the study findings offer a "first step to restoring good flavour in commercial tomatoes".
“Consumers care deeply about tomatoes," he noted. "Their lack of flavour is a major focus of consumer dissatisfaction with modern agriculture. One could do worse than to be known as the person who helped fix flavour."
Klee and his team used targeted metabolomics and natural variation in flavour-associated sugars, acids, and aroma volatiles to evaluate the chemistry of tomato fruits – creating a predictive and testable model of liking.
“This non-traditional approach provides novel insights into flavour chemistry, the interactions between taste and retronasal olfaction, and a paradigm for enhancing liking of natural products,” they wrote.
The samples had a very wide chemical diversity, revealed the researchers – who noted that variation in the aromatic volatiles between the different varieties was as high as 3,000-fold.
Such diversity of chemical make-up presented the researchers with an opportunity to explore what makes consumers prefer one tomato variety over another.
The team performed a series of taste tests with a consumer panel using a subset of the tomato strains that had the widest chemical diversity.
Panellists rated their overall liking of each variety as well as the overall tomato flavour intensity, sweetness, and sourness.
Statistical analysis of the chemistry and taste test results revealed that flavour intensity could be traced to 12 different compounds, whilst sweetness were linked to another 12 – including 8 that were also important for overall flavour.
The analysis also showed that some of the volatiles most abundantly present in tomatoes offer little in terms of ‘enjoyment’ in comparison to other more rare compounds.
“Taken together, the results provide new insights into flavour and liking and illustrate the flaws in a traditional approach based on odour units,” said the researchers.
“The presence of a molecule, even at a relatively high level, does not mean that it significantly contributes to either flavour or liking,” they noted.
The team also revealed that some flavour volatiles influence the perception of sweetness through the sense of smell.
"In other words," said Klee, "there are volatile chemicals unrelated to sugars that make things taste sweeter."
Such a finding raises the possibility that these volatiles could be up-regulated in new breed of tomatoes, or used in other foods to create a zero-calorie sweetness through the noses rather than the tongue.
Source: Current Biology
Published online ahead of print, doi: 10.1016/j.cub.2012.04.016
“The Chemical Interactions Underlying Tomato Flavor Preferences”
Authors: D. Tieman, P. Bliss, L.M. McIntyre, A. Blandon-Ubeda, D. Bies, A.Z. Odabasi, et al