Kathleen Purvis: Do you store tomatoes stem-up or stem-down?

June 11, 2013 

I was kind of hurt when the tomato seller snapped at me.

It was at a local farmers market a couple of weeks ago. A table full of the first greenhouse tomatoes of the season had drawn shoppers like bees.

As we ran our fingers over them, all spread on a table with curved red bottoms up, a woman asked if tomatoes should always be placed stem-down.

I answered that it’s debated. That’s when the man selling the tomatoes interrupted: “I’ve been growing tomatoes for 20 years, I went to tomato growers school in Florida, and they say stem-down.”

I bit my tongue and smiled. I wanted to buy tomatoes, not debate. But in the 24 years I’ve written about food, the stem-up/stem-down tomato rule has changed more often than an uptown traffic light.

The website for the Florida Tomato Committee, which gets information from the University of Florida, says stem-up. So does the University of California, Davis. The theory is that the area around the stem, called the shoulder, is thinner and bruises easily.

That’s contradicted by America’s Test Kitchen, which prints Cook’s Illustrated and Cook’s Country magazines. In 2008, the editors did a test that found tomatoes lose water through their stems. So tomatoes placed stem down keep longer. ATK found that a tomato placed stem-up with tape over the stem lasts even longer.

At ATK in Boston, Lisa McManus is director of tastings and testings. She says the 2008 findings were emphatic.

“Stem-up was definitely not as good,” she says. “We saw a really big difference.” She wondered, though, about the difference at the universities. Could it have to do with packing tomatoes for shipping?

“If I were shipping, I would ship stem-up. The bottom is a curve. It’s going to contact fewer points and there’s going to be less bumping around.”

What I found when I checked with the universities is more debate. Dr. Jerry Bartz, plant pathologist at the University of Florida, said he breaks with the stem-up ruling.

He prefers stem-down, he said. That’s partly because it keeps moisture from escaping, but it also stops bacteria, which gather around the stem scar, from getting into the tomato.

When he’s cutting tomatoes, he doesn’t use a knife to cut a cone around the stem because that would push bacteria into the tomato. He slices across the shoulder below the stem, then trims around the stem.

Got that? OK, but Trevor Suslow, an extension research specialist at UC Davis, disagrees. He’s still a stem-up guy, because the bottom is the strongest point.

Really, he says, the best thing to do is just eat your tomatoes as fast as you can. Then it doesn’t matter whether they’re stem-up or stem-down.

The whole thing reminded me of something else I’ve learned in food reporting: The simplest things are the hardest to prove.

McManus definitely agreed. In the test kitchen, they argue and second-guess constantly. When she started seven years ago, she says, she asked editor Jack Bishop, “Can’t we just say we don’t know?”

He told her, “We’re not real big on ‘We don’t know.’ If I got a tattoo, it would be that.”

Join the food conversation at Kathleen Purvis’ blog I’ll Bite, at obsbite.blogspot.com, or follow her on Twitter, @kathleenpurvis.

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