March 18, 2014 | 5
The other day I went to my local bodega in Brooklyn, New York and bought a 16-ounce plastic carton full of Driscoll’s strawberries. These fruit, the packaging informed me, were grown in Mexico. They looked delicious. I washed them and brought a particularly plump and rosy one to my nose. The aroma, although by no means overpowering, was immediately recognizable and very alluring. As I bit into the fruit, a splutter of flavor washed over my tongue: sweet and subtly earthy, with a hint of something sharp. All too quickly, the taste was gone.
I considered myself lucky. My experiences with supermarket strawberries have vacillated between moderately satisfying and utterly disappointing. In the past I have purchased strawberries that failed to deliver even a smidgen of real flavor. Anecdotally, many people have been similarly dissatisfied. Although you can find strawberries in stores pretty much any month you go shopping, consumer research shows that most people take a chance on the fickle fruit no more than four times each year.
But it’s not really the strawberry’s fault. In the process of creating the modern supermarket strawberry, we inadvertently dulled a lot of the fruit’s once robust flavor and aroma. Now, scientists are learning to bring that scrumptiousness back.
The story of how we changed the wild strawberry into today’s familiar store-bought version begins long ago. We have enjoyed strawberries since the Stone Age. For thousands of years, people gathered the generally small fruit of wild strawberry plants, which grow in temperate regions all around the world. By the 1500s, and perhaps much earlier, people were farming patches of strawberries and growing clumps in their gardens. When Europeans arrived on America’s shores, they discovered a native species known as Fragaria virginia that produced numerous small but scrumptious berries. Explorers brought this species to France in the 1600s. In the early 1700s, a French military engineer and spy named Amédée-François Frézier discovered an especially large-fruited strawberry species growing on the beaches of Chile. He delivered five specimens of Fragaria chiloensis to his home country, where it was grown in fields near Fragaria virginiana. As neighboring plants of the same genus are wont to do, the intercontinental pair mated. Their large, sweet offspring became the ancestors of modern strawberry cultivars: Fragaria × ananassa. It seems fitting that one of the most sensual of all fruit is the child of a French love affair.
To meet the demands of modern industrial agriculture, plant breeders have tirelessly mated Fragaria × ananassa plants that differed in their characteristics, trying to create new varieties with as many desirable traits as possible. They developed strawberry plants that produce large numbers of fruit; they made the fruit themselves larger and firmer; they got plants to grow fruit earlier in the year or nearly year-round; they fortified plants with resistance to many diseases; and they ensured every fruit would blush a lip-staining red upon maturity. Flavor and aroma were rarely the focus of such breeding. It’s not that plant breeders did not care about flavor—they did. But guaranteeing that plants will retain so many different traits generation after generation is incredibly challenging. “Any time a breeder needs to add another important trait into the mix it increases the complexity and the odds of messing things up,” says University of Florida strawberry breeder Vance Whitaker. So breeders prioritize the traits that assure them a livelihood. Flavor was simply not a top priority for the nurseries, shippers and grocers to whom strawberry breeders sold their fruit. The major concerns were yield, hardiness and luster.
Today, farmers around the world grow more than 2.5 million metric tons of supermarket strawberries every year. In the U.S., the vast majority of strawberries are grown in the nurturing climates of California and Florida. Like the ones I bought in Brooklyn, many of the strawberries sold in the U.S. are imported from Mexico, where labor costs are comparatively low.
Modern supermarket strawberries may be the most widely grown cultivars, but they are by no means the only ones. A few groups of farmers and gardeners have preserved dozens of different heirloom strawberries: varieties that were once commonly consumed, but are not produced for the masses today. A few of these neglected cultivars are far more pungent and tasty than what you find at a typical grocer’s. Some gardeners adore nickel and dime-sized Fragaria vesca, also known as Alpine strawberries or fraises des bois (French for ‘strawberry of the woods’), which can be red, yellow or white and mingle familiar strawberry flavor with that of pineapple and rose. Then there’s the somewhat larger musk strawberry, which “has mottled brownish red or rose-violet skin,” tender white flesh and a “peculiar floral, spicy aroma” with hints of honey, wine, melon, raspberry, animal and cheese, writes David Karp in Smithsonian. “Adored by some people, detested by others, the aroma is so powerful that a few ripe berries can perfume a room.” The musk strawberry makes an appearance in Jane Austen’s Emma, published in 1815: at a picnic, everyone agrees that musk strawberries, or “hautboys” as they were called in England, were “infinitely superior” to other varieties—“no comparison—the others hardly eatable.” Another beloved backyard cultivar is Mara de bois, which was bred in France in the 1990s and produces highly fragrant, “exceedingly tasty” fruits halfway between the size of wild strawberries and supermarket fare.
If such tasty strawberries exist, why aren’t we growing them commercially? The trouble is that these varieties often succumb to common crop diseases; they do not make huge numbers of fruit; their intense flavors are concentrated in fruit many times smaller than the ones to which we are now accustomed; and they either turn to mush during long trips from field to supermarket or, if they do make it, have a very short shelf life—all of which adds up to them being too unappealing and unprofitable to grow at a large scale for national grocers.
Instead of trying to commercialize the comparatively tiny musk or Alpine strawberry, some scientists have tried to get their bold flavors into the large modern cultivars. Mating heirlooms with modern varieties to create a new kind of strawberry is impractical because the plants have different number of chromosomes and end up producing sterile offspring. Instead, researchers have attempted to decipher the chemical codes that determine the flavor of both supermarket types and heirlooms and use that information to suss out plants that will produce the most delicious fruit.
As a strawberry goes through its version of puberty, it changes from green to white to pink and finally to a stunning scarlet as a red pigment called pelargonidin 3-glucoside accumulates in its skin. The fruit begins to produce and concentrate sugars and acids. The right balance of these two components is essential to a delicious strawberry: in general people like them on the sweet side. But there’s another equally important and more complex chemical ingredient: volatile organic compounds—highly aromatic molecules that waft off plants and into our noses (think: the biting yet sweet smell of a ripe orange; freshly cut grass; pine trees). Strawberries are known to produce more than 350 different kinds of volatile compounds; heirloom varieties—like Alpine and musk—tend to produce more than standard store-bought fare. Simply having a lot of aromatic molecules in a strawberry is not enough to enhance its flavor, however—they must also be combined in the right way. The wrong mix of volatile compounds, for example, can produce an acerbic bouquet or overpower typical strawberry flavor with an unpleasant grassiness.
Over the years, scientists have pinpointed at least some of the key molecules that make for a delightfully pungent and tasty strawberry. Furaneol, for instance, is so vital to quintessential strawberry flavor that it is also known as strawberry furanone. Another crucial flavor compound, methyl anthranilate, is found in heirlooms, but not in standard supermarket strawberries. Recently, Whitaker and his colleagues discovered some previously unrecognized pieces of the chemical recipe for a delicious strawberry. Between 2010 and 2012 Whitaker and his team grew 35 different kinds of strawberries in Wimauma, Florida and recruited 166 men and women to taste the fruit and rate its flavor, sweetness and texture. The scientists also vaporized and incinerated strawberries inside machines that detected and counted every last sugar, acid and volatile organic compound, creating detailed chemical profiles. Comparing the results of the taste test with the laboratory analysis revealed 17 fragrant molecules that had not been linked to aroma or taste in prior studies.
It turns out that gamma decalactone, for example—which is normally associated with intense peach flavor—contributes to a pleasant strawberry taste, too, when blended with the right aromatic companions. This winter, the University of Florida will fully commercialize a new kind of strawberry known as Florida Sensation™, which has 15-20 percent more sugar than the state’s current leading cultivars, as well as higher levels of gamma decalactone.
Whitaker and his team have also found sequences of the strawberry genome consistently associated with gamma decalactone and are preparing to use this genetic marker to make smarter choices when mating strawberry plants. By taking leaf samples from very young plants and analyzing the DNA within, Whitaker and his peers can determine whether the plants will make gamma decalactone in their fruit as adults, as well as whether they will have a range of other traits. That information helps decide whether to raise those plants to adulthood in the field or not. Maybe a plant has the right genes to make gamma decalactone, but does not have enough disease resistance, in which case they can cross it with a plant that will lack the peach scent, but is immune to pathogens. By analyzing the DNA of strawberry plants to predict their future tastiness and crossing plants generation after generation, the scientists will gradually build a more delicious strawberry. The whole process can take between 5 and 8 years, but DNA analysis will hopefully speed everything up.
Strawberries souped up with science are an appetizing prospect, but we should remember that supermarket strawberries disappoint us for more than purely chemical reasons—there are psychological explanations, too. The modern store-bought strawberry is something of a visual illusion: we have bred it to look superbly sumptuous and, at the same time, drained its perfume and flavor. As a consequence, a standard strawberry—that glistening scarlet heart with its darling wreath of leaves—consistently dazzles the eyes before preceding to disenchant the tongue. That sensory disconnect likely makes the fruit seem even blander than they are. Shopping at a supermarket also robs us of the pleasures of the harvest. A berry picked at peak ripeness will have a firmer texture and more concentrated sugars and aroma than one that has endured several weeks in a dark truck on its way to a grocer. But there’s also something viscerally gratifying about eating fruits and vegetables we have picked ourselves. The joy of plant to hand to mouth is so great that it can sometimes compensate for the absence of robust flavor. “If I let people go out and pick strawberries from the field, they say ‘Wow this is amazing!’,” Whitaker explains. “But I say, ‘This is actually same variety you get in the store.’”
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