The Mystery of Tasteless Tomatoes

tomaques

We were in the main square of the village of Aín, ready to have our evening meal when Pep Pérez came along with a salad and sat in front of us: –Have you grown all that in your plot?— I asked. —Try some tomato.

Pep tended a small vegetable plot with an acquaintance, and was very proud of his tomatoes. And so he should be! There is complete consensus when it comes to the quality of the flavour of fruit, which has declined significantly in recent decades, and this deterioration has been particularly pronounced with tomatoes, eaten fresh or processed.

—So, what do you think?

—Very nice! They actually taste of tomato…

Taste is the result of our gustatory and olfactory senses detecting a large number of chemical compounds. The sense of taste can discern five sensations: sweet, sour, salty, bitter and umami. It is thought that for a tomato to taste good there must be a balance between sweetness (glucose, fructose) and acidity (citric and malic acids), with umami (glutamate) contributing. Nonetheless, the complexity of flavour is provided by the olfactory system. In the case of tomatoes, more than four hundred volatile compounds have been identified, although only twenty of them are considered to be found in sufficient concentrations to influence taste.

«Picking unripe tomatoes may be good for producers, but poses a problem for consumers»

Numerous circumstances have led to the decline in the taste of the tomato. The origin lies in crop production intensification. Tomato-growers, who are paid by weight, demanded highyielding, disease-tolerant varieties, which could be grown all year round (outdoors or in greenhouses), with a long shelf-life after harvest and able to withstand the handling and manipulation associated with their transport and sale. To achieve the latter two objectives, tomatoes are harvested when «ripe green». When the fruits in this state are exposed to ethylene gas, they develop colour and flavour. If left on the vine, they ripen naturally and develop more flavour. However, they are unsuitable for intensive cultivation as ripe tomatoes have lost their firmness and can be damaged during marketing, also harvesting is more labour intensive. Thus, picking unripe tomatoes is good for producers, but poses a problem for consumers: «ripe green» tomatoes are indistinguishable from green ones, when the green fruits are exposed to ethylene gas they develop only colour, but no flavour. Therefore, by eating tomatoes grown intensively you may find some that do not taste of anything at all.

Uniform fruit size was another characteristic that producers sought after. A «perfect» tomato is spherical in some countries, a little flattened in others but, almost always, without cracks on the top, without dimples at the bottom and a uniform red in colour. This feature was introduced shortly after World War II, when uniformly ripening varieties were developed in which –when the fruits are green– they are a uniform green, and so when ripened, they are a uniform red in colour. Recently, as a result of research determining the tomato genome, we have found that this feature is associated with a gene called GLK2. Last year, Mètode interviewed the Valencian researcher Toni Granell, who participated in the research group involved in achieving both these feats. They found the gene encodes a protein involved in the production and distribution of chloroplasts during fruit development. Chloroplasts are organelles in which a reaction between carbon dioxide and water occurs, facilitated by sunlight, to produce sugars. Besides, it is also where many of the chemical compounds responsible for aroma occur when the fruit ripens. Uniform maturing varieties possess a gene variant that makes the protein it expresses inactive. Indeed, when tomatoes without this variant are green, they have patchy dark green areas and, when ripe, they have more flavour, and also have green patches on the top.

There is another reason why tomatoes may be a bit tasteless: when exposed to low temperatures below 10 °C, they quickly and irreversibly lose aroma. It does not matter whether they are exposed to cold after harvesting or before eating. And this affects all tomatoes, so even the fruit of traditional varieties, picked at the optimum moment will soon cease to be delicious if we keep them in the fridge.

A few days after Pep made his salad, a wild boar came down to the vegetable plots. Those in the know spoke of two females with their piglets. One of the areas through which they passed was Pep’s plot but luckily it seems they were looking for tubers and roots and messed up some furrows but did not touch the tomatoes. And so I’ve spent the summer between veggie plots and heat waves, village fiestas and savouring the first figs during my late August strolls…

Tomato confit

In his book Diccionario del amante de la cocina (The Cuisine Lover Dictionary), Alain Ducasse testifies to his love of tomatoes, obviously homegrown during the summer months. He does not hesitate call this a Mediterranean fruit, but later clarifies it originated in America. According to Ducasse, sundried tomatoes are wonderful as they «acquire a fabulous spicy flavour, undetectable when raw». On the line below, he goes on to explain how ovendried tomatoes or, as he calls them, tomato confit can be used in a host of dishes. Here I would like to propose one of these recipes, in which you can use tomato confit to embellish a salad with mozzarella and basil, or a in a pastry pie with arugula salad and parmesan flakes. Ingredients 2kg tomatoes, 3 cloves of garlic, thyme, virgin olive oil, salt. Preparation Peel the tomatoes and cut them in half, lengthwise. Place them on a tray, on silver foil brushed with olive oil. Sprinkle coarse salt, thyme and chopped garlic on top, and some olive oil. Put them in the oven at 80-90 oC, and leave for four hours, turning them over every two hours so they cook properly. Once done, they can be stored in a jar covered with olive oil.

REFERENCES
Ducasse, A., 2004. Diccionario del amante de la cocina. Paidós Ibérica. Barcelona.
Estabrook, B., 2011. Tomatoland: How Modern Industrial Agriculture Destroyed Our Most Alluring Fruit. Andrews McMeel Publishing LLC. Riverside.
Powell, A. L. T. et al., 2012. «Uniform Ripening Encodes a Golden 2-like Transcription Factor Regulating Tomato Fruit Chloroplast Development». Science, 6089(336): 1711-1715.
The Tomate Genome Consortium, 2012. «The Tomato Genome Sequence Provides Insights into Fleshy Fruit Evolution». Nature, 485: 635-641.
Tieman, D. et al., 2012. «The Chemical Interactions Underlying Tomato Flavor Preferences». Current Biology, 22: 1035-1039.

© Mètode 2012 - 75. Online only. The Festive Gene - Autumn 2012
Institute of Materials Science. Scientific Park of the University of Valencia (Spain).