Science Of Strawberries

Goran Ivanisevic’s offer to serve strawberries at this year’s Wimbledon may be a more useful job than he imagined. As well as delicious with cream, this symbol of the summer could help fight cancer according to scientists.

Research has shown that natural plant chemicals in strawberries can inhibit the growth of cancer cells. And now scientists at the Institute of Food Research have begun work to identify the compounds responsible.

“The modern strawberry is just one of hundreds of varieties cultivated worldwide. There are also about twenty wild species. They all have different properties – visible in the size, shape and colour of the fruit, or the size and abundance of flowers. The aim of our project is to identify the properties that play a role in inhibiting carcinogenesis”, says Professor Richard Mithen, Head of Plant Foods for Health Protection at IFR.

The wild ancestors of the most commonly cultivated strawberry today, Fragaria ananassa, can be white, yellow, taste like pineapples, or the stalks can even point the fruit towards the sun. The Institute of Food Research will study both wild and cultivated varieties, and is growing white and pale yellow strawberries as well as red.

In the future, the work could help the team to develop new varieties in which the anticarcinogenic compounds are enhanced.

One of the strawberry chemicals that may play a role against cancer is ellagic acid. Strawberries and raspberries are the main dietary source of ellagic acid in the west. Research by Dr Yannick Ford at Horticulture Research International [1] has highlighted the variation in ellagic acid content between varieties, with some white-fruited strawberries having particularly high levels.

Professor Mithen says, “The great thing about doing research on the health benefits of strawberries is that people enjoy eating them, as I’m sure we’ll see at Wimbledon next week!”

Other strawberry facts:

• Professor Mithen’s research is part of a long term project, and one of many IFR projects analysing the health benefits of fruits and vegetables.
• IFR scientists have also developed a rapid spectroscopy method for detecting adulteration of hand-pressed fresh strawberry and raspberry purees.
• The modern strawberry, Fragaria ananassa, is a hybrid between Fragaria chiloenis from Chile and the North American Fragaria virginiana. The Chilean strawberry, transported to France in 1714, was mainly selected for its large size, while the North American for its hermaphroditism. Hermaphrodite flowers simplify crop production as they enable a crop to be cultivated from a single source.
• The native British wild strawberry is a “diploid” – it has two sets of chromosomes, as in humans. The most commonly cultivated strawberry, Fragaria ananassa, is an octoploid with eight sets. This makes it a good candidate for demonstrating DNA extraction – with eight copies of each gene in the strawberry genome, strawberries are packed full of it.
• The strawberry has a unique structure and is known as a “false” fruit. Unlike any other fruit, the seeds are the true fruits of the plant and are the black dots on the surface. The fleshy ‘berry’ to which they are attached is an enlarged, softened receptacle.
• Both the strawberry and the raspberry belong to the rose family. The English word strawberry comes from the erratic straying habit of the plant, which it shares with many other members of the rose family such as the blackberry.
• A variety developed in 1821 by English market gardener Michael Keens is the ancestor of virtually all modern varieties commercially cultivated today. Its size and flavour caused a sensation.
• The Latin name fraga refers to the fruit’s fragrance.