A ripe heirloom tomato can be an epiphany--soft, juicy, colorful, flavorful.
So why are so many supermarket tomatoes tasteless and rock hard?
Thanks to science, we know why these supermarket shams are so darn miserable.
And what can be done to make supermarket tomatoes totally terrific.
So the first thing you need to know it that tomatoes go through puberty
just like the rest of us.
That’s what ripening is: A hormone driven process that turns juvenile green tomatoes
into mature fruits ready to spread their seeds and get cracking on the next generation.
Tomato puberty kicks off with the simple molecule ethylene.
This hormone activates enzymes that build pigment compounds, such as red lycopene.
And it activates enzymes that build flavor molecules such as β-ionone, which gives tomatoes
a pleasantly floral odor of roses and violets, geranyl-acetone which adds leafy notes, and
6-methyl-5-hepten-2-one, which gives a citrus kick.
Teenage tomatoes also produce enzymes that convert starch to sugar to sweeten the flesh,
and enzymes that break down cellulose and pectin to make the fruit soft and juicy.
Remember, this wonderful cascade of chemistry all begins with ethylene.
Herein lies the root of the problem with supermarket tomatoes: Long ago, the produce industry began
messing with tomato puberty by breeding tomatoes to survive long-distance shipping and still
look good despite the jetlag.
In the 90s, tomato breeders announced a breakthrough: A variety that remained hard during shipping
and then ripened on supermarket shelves or in your fruit bowl.
This travel hardy variety has a mutation that curtails the production of ethylene,
the ripening hormone.
As a result, the biochemical drive to ripen in mutant plants is roughly half of what you’d
find in wild tomatoes.
Less ethylene means harder fruit and easier shipping, but it also means that there are
fewer enzymes to produce flavor and sugar.
This mutation essentially traps the popular supermarket tomato variety midway through adolescence.
This is a fate I would not wish on any life form.
There’s more bad news.
Decades ago tomato breeders also decided that tomatoes should have a uniform red color—
so they bred out the mottled green splotches you see in wild tomatoes and the heirlooms varieties
at farmers’ markets.
Unfortunately, this perfect complexion comes from a mutation in a gene essential for churning
out chloroplasts in the developing fruit.
Chloroplasts are organelles in plant cells that harness light energy to produce sugar.
They are also responsible for the very many pleasurable flavor aromas found in tomatoes.
That means the beautiful mutant tomatoes have less sugar and less fragrance.
Turns out that beauty does really come with a price.
OK, so here's the good news: Researchers in Florida and China recently sequenced the genome of
398 different varieties of tomatoes—wild varieties, heirloom tomatoes, supermarket
charlatans, you name it.
Using human tomato-testers, the scientists figured out which flavor and odor chemicals
customers liked.
Then they tracked the 28 most prized molecules back to the tomato genes that made them.
The team found that—surprise surprise—most supermarket varieties make half of these molecules
at vastly reduced levels.
The researchers also found that when supermarket tomatoes are bred to be bigger, sweetness
comes at the expense of bulk.
With these discoveries, breeders now have molecular markers to help them find a path
to tastier supermarket tomatoes.
Although genetic engineering could restore all the great characteristics to tomatoes
pretty much instantaneously, consumers aren’t keen for GMO fruits.
But growers can still use slower old-school crossbreeding methods to create a tomato with
more of desirable genes.
As we wait for breeders to restore tomatoes to their former glory, here’s a tip for getting the most
out of your red fruits.
Don’t put the tomatoes in the fridge.
Seriously people, science has shown that chilling tomatoes blocks the production of flavor-making
enzymes.
Friends don’t let friends refrigerate tomatoes.
Do you have any produce pro tips to share?
Fire away in the comments.