Nature's Supreme Summer Glory

June 27, 1994|By TIM BAKER

Here's a scientific experiment. Follow these directions:

1. One day this summer take a red, vine-ripened tomato. One that you picked from your own garden or bought at a roadside stand. Take one that you've already kept sitting on your kitchen window sill for two or three days. Hold it in your hand. Does it feel warm? Good. Soft but not bruised or mushy? Good.

2. Cut the tomato into slices, each about a quarter of an inch thick. Put them on a clean plate. Check your watch. Then set the plate on the kitchen table and sit down in front of it.

3. Do not eat the tomato slices.

4. Instead, smell the aroma for three minutes.

5. Now see how much longer you can wait before eating the tomato. Time yourself.

This experiment will give you some idea how William Blake could see ''a World in a grain of sand/ And a Heaven in a wild flower.'' If you know what's going on, you'll see the secret of the seasons in every juicy, red, vine-ripened Maryland tomato you eat this summer.

Consider everything that happens in this experiment. When we start, the tomato is sitting on your window sill. It's been at least

several days since it was picked from its vine and cut off from its biological support system -- deprived of nutrients from the soil and photosynthesized sugars from the plant leaves. But the tomato isn't dead. It isn't even rotting.

It's alive! It's ripening, all on its own. Metabolizing. Breaking down the starches it stored away on the vine and turning them into sweet fructose and glucose.

It's even breathing. A tomato actually exchanges gases with the air in your kitchen. In fact, as it ripens, it begins to breathe more heavily. Sounds erotic, doesn't it? Maybe that's why tomatoes were once called ''love-apples'' and considered an aphrodisiac.

Anyway, the whole time your tomato's innocently sitting there on your window sill, its internal cellular equipment is whirring away. Click, click, click. Genes turning on and off in coded sequences.

One of them triggers the release of ethylene gas which floods the interior and sets off a whole chain of genetic reactions. Additional genes turn on and start producing different enzymes. Some of these weaken the cell walls and soften the tomato's flesh. Others replace green chlorophyll with orange carotene and then red anthocyanins.

All this and more is going on inside that quiet unassuming red irregularly-shaped spheroid that looks so peaceful while it sits there on your window sill. But the most dramatic action is just about to explode.

But when you cut a tomato! Slice it in half!

Within seconds, the shock of oxygen and the disruption of the cells will release new enzymes. They break down a particular fatty acid and immediately convert it into a wildly fragrant compound called (Z)-9-hexenal. It mingles with dozens of other fruit perfumes, and together they play an aromatic summer symphony.

The blended bouquet peaks in three minutes, if you can wait that long.

Take a big bite.

The sugars balance the citric and malic acids to give you that sweet and tart taste that sings the song of nature's supreme summer glory -- a perfect vine-ripened tomato.

A rose might smell as sweet by any other name, but a tomato will never taste this good in winter, no matter what agricultural science, greenhouse design and even biotechnology do to it.

It's a summer vegetable. You must sow your seeds in the back of your laundry room in April, plant the seedlings in May, worry about a late frost, stake, mulch, water, watch out for bugs and rot, and start picking in July and August.

If you can't do all that, then at least you've got to have a favorite road stand on your way home from work and another one where you always stop on the way back from your vacation at the beach.

We do these things for two reasons. Biology demands this process because a tomato has an intimate relationship with the elements.

It begins with April showers, which moisten the ground before planting, and runs through the dog days of August, which warm the picked tomato while it's still ripening on your window sill. When you violate the integrity of that process, you end up with those dull tasteless things you can buy at the supermarket in January.

Slicing open a vine-ripened tomato in summer also nourishes our own internal human processes. We ourselves have an intimate relationship with the changing seasons. Our genes click on and off. They release enzymes. We ripen and mature under a cold rain and a hot sun.

One of the best things about living in Maryland is that we have such distinct seasons. Falling maple leaves in autumn. Swirling snowflakes in winter. Blooming daffodils in spring. And then in summer, those luscious red tomatoes.

Tim Baker is a lawyer who writes from Columbia.

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