UF researchers unlock keys to sweeter strawberries

In this April 4, 2012 file photo, strawberries are on sale at the Downtown Farmers Market in Gainesville.

Matt Stamey/The Gainesville Sun
Published: Wednesday, March 5, 2014 at 2:10 p.m.
Last Modified: Wednesday, March 5, 2014 at 2:10 p.m.

Almost everyone loves strawberries for their bright red color and sweet, but not too sweet, taste.

Scientists at the University of Florida have recently homed in on that uniquely loveable flavor in the fruit, which they say could potentially be used to sweeten other foods in place of sugar.

The study is led by post-doctoral student Michael Schwieterman in the Plant Innovation Program at UF's Institute of Food and Agricultural Sciences. He identified six volatile compounds — out of hundreds in strawberries — that are responsible for the fruit's sweetness.

The 300 or so compounds in strawberries are part of its survivalist strategy, explained Thomas Colquhoun, an assistant professor in environmental horticulture at UF and Schwieterman's adviser.

"The more volatile compounds you have, the more signals that the fruit is ripe," Colquhoun said. That attracts more animal consumers, and the seed dispersal from those helps propagate the plant species, he added.

But only a handful of those compounds are what people crave when they want a sweet strawberry. Using biochemical testing and taste panels of 100 strawberry consumers, the researchers looked at 35 strawberry varieties in Florida over two growing seasons to identify those compounds.

"The main purpose was to discover which volatile compounds drive the flavor of a strawberry so we can reverse engineer an ideal strawberry for greater flavor," Schwieterman said.

In the short-term, this information will allow growers to breed more flavorful strawberries.

In the long-term, however, "The implication is that we might be able to use volatiles to enhance processed foods," like strawberry yogurt, Colquhoun added.

And that would mean adding less sugar to foods, which is better both for strawberry consumers as well as the plant itself, Schwieterman explained.

"If you have a lot of sugar, it (the strawberry) doesn't last as long after harvest," he said, explaining that sugar attracts more microbes, which erode the plant.

The researchers are studying sweet compounds in other fruits now, too, beginning with blueberries. They are also looking for volatiles that suppress sourness.

"We're running down the list of Florida crops: blueberry, peaches and citrus," Colquhoun said. "Once we find these fingerprints, we'll be able to design a very specific mix of volatiles to enhance very specific products."

"With every season that goes by, we're adding another season of data to the matrix," he continued, adding that this is the fourth year that they've studied strawberries.

Years of study on the volatile compounds in tomatoes at UF led researchers to identify six compounds responsible for their sweetness and commercialize the "Tasti-Lee" tomato.

"We speculate that by next season, the strawberries on the market will have specific levels (of volatile compounds) designed to be more flavorful for the consumer," Colquhoun said.

Contact Kristine Crane at 338-3119 or kristine.crane@gvillesun.com.

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