The colder it gets, the sweeter they taste

Summer may be the sweet season, as strawberries, melons and peaches appear in a delicious progression of ripeness. But the sweet tastes of winter are treasured too.

After the first frosts, something magical happens to the vegetables that remain in the garden. It’s quite different from the sugar buildup in summer fruits, designed to entice animals to nibble them and thereby disperse the seeds.

In October, I start to notice how much better the broccoli tastes. As the days’ heat lessens, so does arugula’s “hot” flavor. Radishes and kohlrabi picked during the crisper days of fall are crisp themselves — and sweeter. The hardier lettuces such as oak leaf and the romaines lack the bitter edge they had in August. Mustard greens lose some of their pungency. Cabbages — both the Asian and the Western kind — are milder too.

Spinach becomes luxuriant, its leaves more substantial, flavorful and sweet. All the leafy crops seem improved, and none better than the black Tuscan kale; it attains a sublime mildness and tenderness for the duration of its season, which lasts well into winter. Brussels sprouts sweeten up so well that they rival fruitcake as a Christmas treat.

Of the crops that remain in the ground all winter, leeks are tender and sweet and parsnips bide their time safely, their tissues suffused with sugars. Jerusalem artichokes also accumulate sweetness. Crisp orange “Mokum” carrots become like candy and stay that way until the longer days of February stimulate their growth again.

Humans have evolved with a desire for sweetness — to help us select all those nutritious strawberries, no doubt — but the idea of a “sweet” taste is a complicated one. A great many of the foods we grow and appreciate also contain chemicals used by plants to turn herbivores away — the fire in chili peppers and mustard, the sulfurous bite in an onion, the strong flavors of the cabbage tribe, the bitterness of the chicories.

Plant catalogs use the phrases “sweet” and “mild” to designate the relative absence of these sometimes off-putting compounds, but up to a point they need to be there. We would find them bland if sweetness and mildness were all we tasted, just as a sweet orange or blueberry would be unexciting with no acidic tang.

Those winter carrots satisfy because of a balance between their sugars and the resinous-tasting turpenoids that identify them as carrots. Without that, they’d be as dull as those watery, “supersweet” corns. I suppose that modern science will soon have the power to transform all our vegetables into characterless sugar lumps, but let’s hope it stays its hand.

If you want to know what an inappropriately sweet vegetable would taste like, just let your potatoes get too cold in storage. When the temperature drops below 40 degrees for a while they get so sweet that factories must reject them for chip and french fry use — the excess sugar causes the flesh to scorch when fried. That might not be a problem for home use, but the un-potato-like flavor could certainly be. If this happens to yours, just move them to a 45- or 50-degree spot and the excessive sugar will turn back to starch again.

The sweetening-up of plants as an acclimation to cold is a complicated business, and has bedeviled far better minds than mine. It’s not just a matter of sugar-as-antifreeze, even though sugaring the water in your plumbing pipes will certainly lower their freezing point. A plant must already have other cold-hardy traits (subtropical sugar cane is freeze-tender despite the sugar in its stems). Photosynthesis slows down in cold weather, and both starches and sugars tend to accumulate for later use instead of fueling growth. Sugar seems to have the effect of strengthening cell walls — a good cold-weather strategy. It also curbs the action of decay organisms — hence its addition to jellies and jams.

Whatever the process is, I’m glad it is happening. Some of the greatest pleasures of the coming year will be the result of the seasons’ changes and the foods appropriate to them. And many of them would not be possible without my home garden, or a garden nearby.

Those delectable Mokum carrots are never shipped long distances because they snap like icicles when you drop them. And the first treat of the spring season — asparagus spears that will poke up out of the still-cool ground — must be eaten right away. They start to lose both flavor and sweetness within a day of picking, and after warm weather sets in their general quality starts to decline too. But by then there will be plenty of Sugar Snap peas. And right now there are fat, pale parsnip roots hiding under the ground. Nothing like a parsnip to sweeten a winter day when it’s roasted in butter.

Barbara Damrosch

Barbara Damrosch

Barbara Damrosch’s latest book is “The Four Season Gardener’s Cookbook.”

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