Smithsonian.com

Photo: holtmi

Give a baby her first spoonful of mashed spinach or blended brussell sprouts and you can likely watch her face pucker up in shocked torment. Veggies tend to be a dreaded childhood bane for many youngsters, yet there are exceptions to the vegetable hate rule. Sweet potatoes and carrots, for example, tend to score highly. But why is that? As a general rule, much of our likes and dislikes spawn from sweetness – or at least our perception of it.

Evolutionarily, we’re programmed to like sweetness, since it’s indicative of calorie-rich sugar. Millennia ago, when we were just beginning our evolutionary journey as Homo sapiens, those individuals who preferred and thus consumed sugar had an edge. Sugar imparts a quick energy boost, so desiring, locating and consuming sugar-rich food could mean the difference between out-maneuvering a predator, keeping warm during a cold night or bearing healthy children. Our closest relatives, such as chimpanzees, also share this propensity towards the sweet. Chimps regularly concoct creative ways to brave beehives to reach the sweet honey inside.    

In today’s world of car commutes, office jobs and sugary snacks, however, our attraction to sugar turns against us, helping to fuel an epidemic of obesity. The processed food industry realized this a long time ago when it dawned on them that cranking up the sugar content of even the most cardboard-like snack automatically makes it delicious to our primitive food brains. 

But sugar, it turns out, is not the only sweetness driver. The sweetness of a farmer’s market strawberry or a hand-picked blueberry comes largely from volatiles, or chemical compounds in food that readily become fumes. Our nose picks up on and interacts with dozens of these flavorful fumes in any given food, perfuming each bite with a specific flavor profile. The sensations received by smell and taste receptors interact in the same area of the brain, the thalamus, where our brain processes them to project flavors such as sweetness. ”The perception of sweetness in our brains is the sum of the inputs from sugars plus certain volatile chemicals,” said Harry Klee, a researcher with the university’s Horticulture Sciences Department and Plant Molecular and Cellular Biology Program, said at the American Association of the Advancement of Science conference, held last week in Boston. “The volatiles act to amplify the sugar signal so that we actually think there’s more sugar in the food than is actually present.”

A dozen or more volatiles can occupy a single food. Some trigger the sensation of sweetness, others of bitterness or sourness. If we could better understand just how these chemicals interact in foods and in our brains, we could genetically tweak foods to be more to our liking.

Scientists from the University of Florida think that “fixing the flavor” of foods such as tomatoes would make them more appealing to shoppers, which on the long run may facilitate a healthier society. “If we make healthy things taste better, we really believe that people will buy them more, eat them more and have a healthier diet,” Klee said. “Flavor is just a symptom of a larger problem,” he continued. “We have bred crops for a higher yield, while quality and nutritional value have dropped.” 

What we think of as flavor actually has a great deal to do with the subtle smells of volatiles. Not convinced? The researchers predicted as much. In Boston, they whipped out samples of gummy bear-like candy (raspberry and blueberry Sunkist fruit gems to be specific) to prove the power of volatiles to the audience. As instructed by the Klee and his colleagues, I pinched my nose shut tight, then popped the candy into my mouth, chewed and swallowed half of it. As if I had a seriously stuffed up nose from a bad case of the flu, the candy felt squishy and lackluster on my tongue. This bland sensation, the researchers explained, is taste. Now, they instructed unplug your nose, and swallow the rest of the gummy candy. A wave of intense sweetness hit me like a sugary rainbow of fruity flavor. This is olfaction at work, explained Linda Bartoshuk, one of Klee’s colleagues at the university’s Center for Smell and Taste. “Who experienced a rush of flavor and sweetness that seemed about twice as powerful as before?” she asked. In a room of around 100 people, about half the hands shot up. 

Several years ago, Klee made a mission of saving the modern tomato’s flavor in the hopes of ultimately improving consumer health. Those efforts have led him down a winding vine of chemistry, genetics and food science. 

Rather than starting his investigation with tomato growers–who are paid to churn out attractive tomatoes, not make a flavorful food–Klee began with consumers, or the people who buy and eat tomatoes. He wanted to understand what makes good and bad flavor on a molecular level. Figuring out the formula for creating a delicious tomato that still maintains the high yields and disease resilience of the watery, bland supermarket offerings could give growers an easy-to-implement toolkit for improving their offerings.  

Klee and his colleagues ground up dozens of tomato variety, then asked 100 different people to sample the fruits of the researchers’ labor and report back on their favorites and least favorites. Using that feedback, the researchers could identify which of the tomatoes’ more than 400 volatiles actually drove flavor. What they found indicated that consumers prefer tomatoes with a perceived sweetness – emphasis on “perceived.”

For example, yellow jelly beans, a breed of tomato, contain around 4,500 milligrams of sugar per 100 milliliters. A matina tomato, on the other hand, contains around 4,000 mg per 100 ml. Yet people perceive matinas as being about twice as sweet as yellow jelly beans. Volatiles drive the perception of what we think is sweetness in these two tomatoes.

Typically supermarket variety tomatoes vary in their sugar content, but they usually range from around 2,000 to 2,500 mg per 100 ml. The cherry tomato varieties typically sit in the 3,000 to 3,500 mg per ml range.

Just 15 to 20 volatiles control the majority of a tomato’s flavor, the researchers found.  ”Some of the most abundant chemicals in a tomato have absolutely no influence on whether people like it or not,” Klee said.

This knowledge in hand, they went about creating a recipe for the perfect tomato, which resembles an heirloom. Their ideal fruit represents the average of what the research participants ranked as their preferred tomato. While absolute individual preferences may vary by demographics, cultures and whether or not someone is a supertaster, Klee believes that nearly everyone would agree that “this is a really good tomato.” 

The next step, Klee says, is to move those desirable traits into the high yielding varieties of tomatoes. In the lab, he and his team successfully crossed modern tomatoes with their perfected heirloom, creating a hybrid. The new tomato maintains the deliciousness of the volatile-laden heirloom but produces twice as much fruit and keeps the modern strain’s resistance to disease. So far, yields aren’t quite at the level to convince commercial growers to change their ways, but Klee believes production improvements will get his tomato to the marketplace eventually. 

“Can volatiles enhance sweetness while reducing our use of sugars and artificial sweeteners?” Bartoshuk posed. “We think: yes.”

Miracle berries. Image courtesy of Flickr user roboppy

If you’re Jewish—and maybe even if you’re not—there’s an excellent chance that you will eat latkes sometime before the end of Hanukkah next week (it starts tonight). I fully support this: Latkes are delicious. It wouldn’t be Hanukkah without them. (I’m going with a zucchini-potato version this year to fit in with my low-carb pregnancy diet.) But are you going to eat them all eight nights of the festival of lights? Probably not.

I’ve been thinking it’s time to throw some new food traditions into the Hanukkah mix. I have a few ideas to propose:

Have a fryapalooza. The reason latkes are so associated with the holiday is that they’re fried, evoking the miracle of the oil that was supposed to last no more than one night but lasted for eight. So why stop at shredded potatoes? Have a fried-food fest that would put the Iowa State Fair to shame.

There are at least two ways you could go here. One is down-home, with fried pickles from Homesick Texan; corn dogs from Average Betty (using Hebrew National wieners, of course); Paula Deen’s Southern fried chicken; and don’t forget your veggies—Grit magazine’s fried zucchini, perhaps. For dessert, if you and your guests aren’t doubled over with stomachaches by this time, may I suggest funnel cakes, those crispy fried dough treats dusted with powdered sugar? Moms Who Think shows you how to make them.

Another way to go would be a world tour of fried food. Mediterranean appetizers could include Spanish-inspired smoky fried chickpeas from Food52 or Italian fried olives from Giada De Laurentiis. Japanese tempura vegetables have a lighter, more delicate flavor than their Western counterparts; Leite’s Culinaria shares a recipe from Yotam Ottolenghi’s new vegetable cookbook Plenty (which I’m hoping Hanukkah Harry brings me). And, though less famous than the cheesy Swiss version, fondue bourguignonne, where pieces of meat are speared on a fondue fork and cooked in hot oil, lets your guests get interactive. Make your final stop in Israel for a dessert that really is a Hanukkah tradition, the jelly doughnuts called sufganiyot; Chow shows how it’s done.

Whichever way you decide to go, this fatty menu should probably be followed by a juice cleanse. Of course, you could always space these recipe ideas out over the course of the holiday instead of eating them all in one go. But where’s the fun in that?

Dip it, don’t fry it. There’s no rule that says oil is only for frying. In fact, as Italians and other people from around the Mediterranean have long known, some oil is just too delicious to waste by heating away its flavor. You could host an olive oil tasting party with quality oils and slices of good bread, then follow the tasting with a meal of salads and other dishes that highlight the star ingredient. Kim Vallée and Fine Cooking magazine both offer suggestions for pulling it off.

Eat a miracle (fruit). Unlike the Passover story, which requires the whole Haggadah to explain, the Hanukkah story is told succinctly by the dreidel, the spinning top with four sides spelling out in Hebrew, “A great miracle happened there.” Although the name has more to do with marketing than divine intervention, so-called miracle fruit is pretty neat anyway. Miracle fruit is a West African berry that temporarily alters the way you perceive flavors, turning everything sweet—even something as sour as a lemon—for a while. It’s similar, though much more dramatic, to what happens when you eat an artichoke. The berries are available frozen, dried or in tablet form, or you can buy seedlings and grow your own. You could turn the evening into a game, serving an array of foods, some with bitter or sour flavors, and asking blindfolded guests to guess what they are.

Fuyu persimmons, courtesy of Flickr user outdoorPDK

The first time I tried a persimmon was a few years ago. I spotted the attractive fruit at the supermarket, and its smooth skin and deep orange color tempted me to buy one. Unfortunately, I didn’t know that the variety of persimmon I bought—hachiya—shouldn’t be eaten until it is extremely ripe. It tasted like industrial-strength cleaner. Since then, I’ve learned that fuyus, which are short and squat, are the variety to buy for eating fresh; pointy-bottomed hachiyas are better for baking.

Fuyus have a pleasantly firm, mango-like flesh. The most similar flavor I can think of is papaya—sweet, but not overly so, with a hint of floral or spicy tones. Both fuyus and hachiyas are usually available in late fall and early winter. Here are a few ways to use either variety:

1. In a salad. Despite originating thousands of miles apart, persimmons (from East Asia) and pomegranates (from the Middle East) harmonize nicely—both flavor-wise and visually—in a fall/winter fruit salad. For an even more colorful (and very nutritious) dish, toss them with sliced red cabbage, Romaine lettuce, Asian pear, hazelnuts and gorgonzola cheese, as in the Rainbow Chopped Salad from Epicurious.

2. As a condiment or accompaniment. Organic Authority suggests serving a fresh persimmon salsa with grilled fish or chicken. Or it can be cooked into a spicy chutney with apples and raisins, as Moscovore recommends. Firm fuyus can also be sliced and roasted to be served as a sweet/savory side dish, as in this recipe from About.com.

3. Dried. Hoshigaki, or dried persimmons, are a popular treat in Japan, where they are made through a labor-intensive process you’re unlikely to want to replicate at home. But even the shortcut method you can make in your oven—like this recipe from Martha Stewart—produces a yummy (albeit very different, I’m sure) snack.

4. In a drink. Just because I’m teetotaling for the next few months doesn’t mean you have to. Imbibe magazine’s recipe for a persimmon margarita rimmed with cinnamon salt is a novel twist on one of my favorite cocktails. On the nonalcoholic side, 101 Asian Recipes explains how to make a Korean persimmon tea.

5. In dessert. Nicole of Pinch My Salt shares her grandma’s recipe for sweet, moist persimmon cookies. And I would like to be in Denise’s Kitchen next time she makes this delicious-looking fuyu persimmon, pear and walnut rolled tart. Having spent only one very rainy day of my life in Indiana (on the interstate en route from Nashville to Chicago), I was unaware that persimmon pudding was a traditional regional food there. Joy the Baker explains how it’s made (including how to wheedle the fruits from your neighbor), describing the result as “sweet and super moist bread pudding meets spice cake.” Sounds good to me.

Delicious looking watermelons, courtesy of Flickr user whologway

If watermelon were a brand, it would be a very successful one. First of all, it has a name that tells you exactly what it is—at more than 90 percent water, it’s the juiciest fruit going. It has attractive packaging. Plus, it’s got impeccable timing. It doesn’t even bother making an appearance until summer really heats up and all anyone wants is something cool, sweet and hydrating. If they could only figure out that seed problem. (Sorry, so-called seedless watermelons are neither truly seedless nor, in my experience, as good as the original.)

The best way to eat watermelon? Straight up, by the wedge, bare feet dangling into a pool, lake or other body of water. But here are five other pretty good ideas:

1. Salads. It’s Greek. It’s salad. But it’s not Greek salad. Toss together some watermelon with feta cheese and olives and you’ve got the basics of a classic Aegean summer dish. For a twist: Grill the watermelon, as Recipe Girl does, to caramelize the sugars. Jacques Pépin adds fresh mint and Tabasco sauce. The Food Section gives equal billing to another quintessential summer fruit, tomatoes. Bobby Flay takes it in a Southwestern direction by swapping in jicama instead of olives and feta and adding lime juice.

2. Drinks. Watermelon is practically a beverage already, but it’s also a natural in cocktails and nonalcoholic drinks. You can mix up a Mexican-style agua fresca with lemon juice and mint. What’s Cooking in America makes the novel suggestion of blending watermelon puree with rosewater and lime juice. Imbibe magazine offers a spicy watermelon margarita recipe for those who like that hot-cold, salty-sweet combination. Or just cut to the chase and spike the whole melon with vodka (recommended only if you have a large group of friends to help finish it off).

3. Soups. The most ubiquitous summer soup isn’t necessarily made with tomatoes; a watermelon-cucumber gazpacho from Salon comes with a Spanish cultural history lesson. I’m intrigued by the addition of buttermilk and rosewater (apparently not as novel an ingredient as I thought) in a Bulgarian chilled watermelon soup. Thai-spiced watermelon soup with crabmeat from Epicurious also sounds delicious.

4. Dessert. Watermelon only needs the slightest nudging to be taken into the dessert category—Wicked Good Dinner explains how to make a watermelon granita by simply freezing the pulp with some salt and sugar and adding fresh basil. “Watermelon” ice cream pie is adorable but it’s made with lime and raspberry sherbet; Emeril Lagasse offers a recipe for real watermelon-flavored ice cream with chocolate chips (they look like seeds).

5. Pickled. You don’t have to be a freegan to want to minimize food waste. Why throw away all that watermelon rind when it only takes a couple of days or so to turn it into pickles? Seriously, according to The Bitten Word, they’re not very complicated to make, and if you’ve never tasted sweet-sour pickled watermelon rind you are missing out on one of the triumphs of southern pickling. Pickled pig’s feet, on the other hand, I’m not so sure about.

“Great news, Mom and Dad—Matt and I are having a cucumber plant! And some peas, and tomatoes, and beets, too. I know we should wait to tell people until we’re certain they’ve germinated, and there’s a long way to go before they actually fruit, but we just planted the seeds yesterday and we couldn’t be more excited. Matt already built the (raised) beds.”

Somehow, I don’t think this imaginary conversation with my parents would cause quite as much commotion as a similar announcement my brother and his wife made nine years ago. Theirs was accompanied by a picture of their first daughter’s ultrasound. Even though most embryos look pretty similar at that stage, it’s always awe-inspiring to see a brand-new person forming in the womb (and I can only imagine the awe is increased a hundredfold if the womb is your own). There is the head with beginnings of eyes, the tiny appendages that will someday turn into limbs with fingers and toes.

What I never realized was that a similar process happens in the plant kingdom. Inside every seed are the basic parts of a fully formed plant: immature roots and tiny leaves curled up like a vegetal embryo. As it turns out, they’re even called embryos. Within the seed’s protective wall is also a food called endosperm that nourishes the embryonic plant as it starts growing into a seedling.

Friends who have had children in recent years signed up for daily emails telling them what was happening to their fetus at that point in its development. As a novice gardener starting my first vegetable garden, I have a similar curiosity (obviously, on a far less emotional scale) about what’s going on just under the surface of my newly planted raised beds. If things are going well, three days after sowing, my little ones should be in the early stages of germination.

First tomato seedlings, courtesy of Flickr user amandabhslater

I got a preview of how this happens when I tried sprouting radish seeds a couple of months ago. The seeds were soaked in water, then rinsed twice daily to keep them moist. This, plus sufficient warmth, was enough to make the seed coating break down, which released enzymes that caused the embryo to grow into a sprout, or the beginning of a plant—though they wouldn’t ever reach full “planthood” without soil and sun.

The same thing is (I hope) happening under the soil with my vegetable seeds, although the required conditions vary slightly for different seeds. Some need warm soil, some need cooler temperatures, and a few require some light to properly germinate (all of which are helpfully spelled out on the seed packets). Larger seeds contain more endosperm, meaning they can be planted deeper into the soil and be nourished as they grow roots and shoots. I enjoyed seeing all the different shapes and sizes of the seeds—beets were knobby and irregular; lettuce, tiny, smooth and lozenge shaped; peas were, well, peas.

This Discovery Channel video explains the germination process in simple terms: After the seed coating breaks apart, the first root, called the radicle, starts to grow downward in search of nutrients. Then another shoot, called a plumule, grows up in search of light. With the help of nutrients from the soil, plus water and light, it will continue to grow to maturity.

The best part of all? No need to save for their college tuition. Although, between seeds and materials and tools, I could see how gardening could become an expensive hobby.