If you shop in a supermarket you may well have asked why the fruit and veg you buy there is so tasteless, especially if you’ve also tried homegrown alternatives. Traditional breeds of tomatoes usually grown in gardens, known as heirloom tomatoes, for example, are often small and strangely shaped and coloured but renowned for their delicious taste. Those in the supermarkets, meanwhile, are often pumped up in size but somewhat insipid to eat.
This is because plants used by most tomato farms have gone through an intensive artificial selection process to breed fruit that are big, red and round – but at the expense of taste. Now a 20-strong international research team have identified the chemical compounds responsible for the rich flavour of heirloom tomatoes and the genes that produce them. This information could provide a way for farmers to grow tomatoes that taste of something again.
The unique flavour of a tomato is determined by specific airborne molecules called volatiles, which emanate from flavour chemicals in the fruit. By asking a panel of consumers to rate over a hundred varieties of tomato, the researchers identified 13 volatiles that play an important role in producing the most appealing flavours. They also found that these molecules were significantly reduced in modern tomato varieties compared to the heirloom ones. And they found that bigger tomatoes tended to have less sugar, another reason why large supermarket fruits often fail to inspire.
Tomatoes originally hail from the Andean region of South America and belong to the Solanaceae family, making them relatively close relations of potatoes and peppers. The original, ancestral tomato was very small, more like a pea, showing just how much human intervention has swollen the fruit. We don’t know how long they have been grown for human consumption but they had reached an advanced stage of domestication by the 15th century when they were taken to Europe.
Before the 20th century, tomato varieties were commonly developed in families and small communities (which explains the name “heirloom”). With the industrialisation of farming, the serious business of tomato breeding began with intensive selection for fruit size and shelf life.
Some more recent effort has been put into improving the flavour of tomatoes through breeding. But the new research appears to indicate that this has ultimately been unsuccessful and that earlier breeding efforts have doomed modern commercial varieties to mediocrity.
The new paper, published in Science, emphasises what seems to be a constant conflict between the food industry’s desire for profit and what the public actually want. The researchers tactfully excuse the way tomatoes have been bred for size and shelf-life at the expense of taste as being down to breeders’ inability to analyse the fruit’s chemical composition and find the right volatiles.
But many people will find this hard to swallow. After all, the new research itself used the most ancient volatile analysis system there is: the human taster. It wouldn’t have taken much for farmers to incorporate taste trials into their breeding programmes.
Because modern farmed tomatoes have only lost their flavour in the last hundred years or so and varieties are still available that produce the tasty volatiles, it should be possible to reinsert the crucial taste genes back into commercial varieties. This could be done by genetic modification or conventional breeding. Just as we are seeing a resurgence in organic and artisan growing, it would be great to see a new generation of tomato breeders interested in returning flavour to the fruit using wild and heirloom varieties, while maintaining other commercially desirable traits.
There is significant public opposition to the idea of genetically modifying foods by inserting genes into a plant’s DNA in the lab. But the idea of reinserting lost genes may be more palatable to the public than introducing completely new ones. Either way, it shows how perverse the food industry’s methods are that we may need to use one of the world’s most advanced technologies to give an inherently delicious food some flavour.