Alibi V.27 No.29 • July 19-25, 2018 

Know Your Ingredients

What is an heirloom tomato?

And why are they so tasty?

Heirloom tomatoes come in all colors, shapes and sizes
Heirloom tomatoes come in all colors, shapes and sizes

Tomato season is nigh, a fact that makes many foodies—yours truly, included—very happy. Do you remember the first time you tasted a homegrown tomato, when you realized that the styrofoam-flavored red things you buy at the supermarket had been lying to you about how good a tomato can be? Yeah, that’s called the tomato moment, and it’s the gateway into suddenly getting picky about the quality of your fruits and veggies. Once you’ve had the real thing, it’s hard to go back.

If you’re one of the converted and no longer accept subpar tomatoes, you probably know that heirloom tomatoes are where you’ll find the widest variety of flavors. But what, exactly, is an heirloom tomato? And why are they so much better than the run-of-the-mill Best Boys and Early Girls we’re all used to?

The particularities of what make a given variety of tomato—or any seed, for that matter—an heirloom are debated, and there are no real hard and fast rules. Generally speaking, though, an heirloom variety is a non-hybrid, meaning that it hasn’t been cross-pollinated with any other varieties (at least, not for many generations). It can be thought of in the same terms as a thoroughbred dog: Growers select qualities that they like in a certain variety—a taste, color or even resistance to disease—then allow that variety to “breed true” for several generations. In this case, breeding true means that the plant self-pollinates, and the seeds produced from these tomato varieties will grow into tomatoes with the exact same DNA as the parent plant.

Heirloom, of course, also means old. Many of the heirloom varieties of tomato grown in the US today were brought over as seeds by immigrant families decades or even centuries ago, and have been preserved by dedicated growers ever since. The purply-red Black Krim originally hails from Russia, for instance, and the Tomaccio is a “created heirloom” from Israel bred from a wild Peruvian tomato varitey.

So, why do heirloom tomatoes taste so much better than hybrid varieties? Commercial tomato varieties—beefsteak, Roma and cherry, among a few others—are bred for uniformity and mass production, not for flavor. While these qualities might have made tomatoes more marketable in the Depression Era, they do not hold much appeal with the current era of locavores who prize the marbled colors, bizarre shapes and vast spectrum of flavors that many heirloom tomatoes display.

In recent years, a biochemist at Stanford named Ann Powell made further discoveries as to why commercial tomato varieties bred for high yield and unchanging appearance just don’t taste very good. According to an article in the Stanford Alumni magazine summarizing Powell’s findings, “the mutation that promoted uniform ripening had also knocked out a gene needed for the full development of sugars in the fruit.” While there is no scientific unit to measure tastiness, I feel pretty secure in claiming that a tomato with more natural sugars in it is going to taste decidedly better.

While heirloom varieties are your best bet for finding truly outstanding flavor, there are valid arguments for the genetic strength of hybrid varieties, too. Heirloom varieties tend to be less disease resistant and more finicky about the climate they’re grown in, which are the main reasons they’re not grown more commercially. To the converted, though, the extra effort put into growing them just makes them taste that much sweeter. The best way to ensure you’re flush with tasty tomatoes all season? Pick up a plant at the farmer’s market, find a sunny spot for it and give it plenty of love.