2017-02-16 09:32:03
Nobody knows the true flavor and aroma of the tomato until it is taken directly from the bush in its ideal state of ripeness, when the fruit has completed its life cycle and contains all the sugars and volatile substances that delight our palate.
The taste does not depend only on our taste buds, it is actually the result of the interpretation of a set of sensations from different places. Some come from our mouth. When biting into a tomato, we notice its acidity, its texture, the set of chemical substances that activate our palate,… but that is only a small part of everything. Before even sinking its teeth into it, the tomato has already sent us a bunch of signals in the form of volatile chemicals that permeate the air and are detected by our olfactory system. In the end, it is the brain that adds all this information to generate the flavor of a fruit.
Unfortunately, the tomatoes we buy in the supermarket are painfully bland. There are several reasons that we can point to to justify the loss of flavors and aromas. For starters, the variety being sold has been selected from a huge number of genetic crosses that favor characteristics that have more to do with sight than taste and smell. More attractive varieties have been sought, with a more showy colour, shape and size, more resistant to pests and whose fruits ripen slowly so that they can be collected, stored and distributed, without spoiling, to markets that are sometimes located thousands of kilometers away from the place of origin. In many cases, the tomato is picked green and ripens artificially so that it reaches our hands in the best and most attractive conditions. As you can see, none of these reasons deals with preserving the flavor and aroma and, as a consequence, they have been lost.
Our guest today, Antonio Granell Richart, a researcher at the Institute of Plant Molecular and Cellular Biology (CSIC-UPV), has participated in an international scientific study that has drawn up a genetic roadmap to recover the flavor of tomatoes. It has not been an easy job, there are thousands of tomato varieties spread all over the world, some modern and others old, some adapted to the most developed cultivation methods and others wild that live in the most unusual places, including deserts. All of them have genomes that differ from each other. The tomato genome has close to one billion genetic letters (nucleotides), approximately one third of those contained in the human genome. From the ancestral genome of the first wild tomato, thanks to human intervention, changes, additions and losses of genetic material have been selected that have given each variety its particular appearance and properties. Searching, among the enormous amount of information on the genome of each variety, for those genetic differences that are linked to flavor and aroma has been an enormous job.
One of the objectives of the researchers was to identify the volatile compounds associated with flavor, but… it is not that simple, because “there is nothing written about taste.” To the variety of volatile compounds released by the tomato, of which only a few are linked to flavor, we must add the number of olfactory receptors that each of us have, as consumers, receptors that can vary from one to another, to the point that the same chemical substance that reaches our nose mixed with the air can be detected by one person with an intensity 1,000 times higher than another.
With these premises, the researchers have carried out a study in which they have had to take into account the volatile compounds released by tomatoes, the genetics associated with them and the reactions of a group of volunteers who have put their noses to the science service.
To identify the parts of the genome associated with volatile substances involved in aroma and flavor, the team of researchers performed comparative sequencing of 398 modern, traditional, and wild tomato varieties. The closest relative of the tomato was also included, to obtain data on the fruit before humans intervened in its selection. Of all the chemical compounds in tomato, 37 directly related to flavor intensity were identified. Of all of them, the analysis of modern varieties compared to the oldest ones allowed us to identify at least 13 volatile compounds associated with flavor that have been lost or drastically reduced.
Once the culprits for the taste and aroma of tomatoes have been discovered, the results of the research are now placed in the hands of companies specialized in the selection of new varieties. It may be that, in a few years, our salads will be appetizing again thanks to science.
I invite you to listen to Antonio Granell Richart, a researcher at the Institute of Plant Molecular and Cellular Biology (CSIC-UPV).
Reference:
Tieman et al., A chemical genetic roadmap to improved tomato flavor. Science 27 Jan 2017: Vol. 355, Issue 6323, p. 391-394 DOI: 10.1126/science.aal1556
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