Do you find the tomato skin harder than ever? It has an explanation

ViladecansWe are at the Baix Llobregat Agrarian Park surrounded by tomato plants and under a scorching sun. "We have planted 540 varieties of tomatoes," says Jaume Torras, owner of SoulBlim. He grows and supplies fruits and vegetables for the restaurant industry (he previously had a market stall and sold to individuals through his website, but for some years now he has only worked for professionals) and has recently become part of the Catalan Academy of Gastronomy and Nutrition (ACGN). Today he presents his project, we taste all kinds of tomatoes, we discover things we didn't know and confirm others we suspected, such as the fact that many tomatoes have tougher skin than ever. Why?

The question is asked by the chef and vice-president of the Academy, Carme Ruscalleda. Torras confirms it and attributes it to genetic crosses that have sought to have tough-skinned tomatoes. First, for a variety from the Canary Islands, but later, and especially, for the crops in Andalusia and Murcia. This way, the fruit has room to travel and arrive in Northern Europe in good condition. We review the science behind it, and we will finish with Ruscalleda's advice on how to deal with this thick skin that is difficult to cut and often crushes the tomato.

Science can explain it

Marta Pujol, IRTA researcher at CRAG specializing in horticultural plant genomics, explains to ARA that "there are many new varieties arriving thanks to genetic improvement programs." The criteria for developing these varieties involve improving specific aspects, such as those that aim to facilitate cultivation and, for example, make the plant resistant to diseases. Others are linked to consumption, affecting the color of the tomato, making it juicy, or acting on its texture. And there are also those linked to sustainability, such as making the plant require less water. Fruits lasting longer once harvested is also related to this issue, as if the fruit spoils, food waste increases. "The tomato has a very short post-harvest life. It loses water and turgor, and spoils in a short time. Fungi arrive and it can rot," says Pujol. The tough skin protects it from all this. An example of a tough-skinned tomato is the "tomàquet de penjar" (hanging tomato), whose thick skin protects it from fungi. "It doesn't rot and we can keep it for up to 300 days in perfect condition," explains the researcher.

Genetic improvement programs (which should not be confused with gene editing) are carried out through crosses, such as those aimed at improving firmness. "When the tomato ripens, it softens. Enzymes break down the cell walls. It changes color, sugars are released, aroma appears... many things happen," says Pujol, who adds: "Since it is known to lose firmness, varieties are sought where this happens more slowly or not at all. But since the process is complex, you might lose something else. If we significantly alter ripening, we might lose flavor."

In fact, the idea of the tomato losing flavor is a widely shared concern among consumers. Marta Pujol explains that in 2024, the magazine Nature published an article on this fact that justified the loss of flavor by selecting large specimens, which have less sugar, during plant domestication. With current scientific advances, this has been reversed, and it is possible to have large and sweet tomatoes. Local varieties have also been recovered and improved, such as a tomato from Collserola.

In the future, moreover, it will be possible to be more precise. The European Union has approved the law for genetic editing, so a single factor can be modified without the risk of destabilizing others. "Interventions so small they could have occurred spontaneously in nature," explains Pujol. In a couple of years, it will be possible to work with these advances. With the current technique, a new variety can take eight years to reach the market, and with genetic editing, deadlines will be shortened. "We will have better tomatoes every time," assures Pujol. Currently, there is practically no consumption of transgenic foods in Europe, beyond cereals arriving from abroad, which have passed many controls and are intended for animal consumption.

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