VOLUME 32, NUMBER 31 THURSDAY, May 10, 2001
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Capaldi explores preferences for tastes
Provost's work finds that taste preferences are learned, and can be modified

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She says she loves to eat-spaghetti is her favorite food-and is reportedly an excellent cook. So it's only natural that Provost Elizabeth D. Capaldi-a psychologist by training-would bring her love of food into the research lab.

  In addition to managing the academic aspect of the UB operation, Provost Elizabeth D. Capaldi maintains an active research lab in Park Hall.
Photo: Frank Miller
Focusing specifically on taste preferences, her work with rats, college students and even 5-year-olds has found that very few taste preferences are genetically determined. In fact, most are learned, she says, and therefore can be modified.

Capaldi's used one of the few genetically built-in taste preferences, that for sweet, to teach college students to enjoy broccoli and children to like grapefruit juice.

The secret? A sprinkling of sugar.

Capaldi, who maintains an active research lab in the basement of Park Hall, acknowledges that most parents resist this tactic, called flavor-flavor learning. But after five to 10 servings of the sugar-sweetened vegetable or juice, the sugar can be withdrawn and the food will be consumed. Unsweetened.

"That's a method that will actually work," she stresses, noting that the pleasure associated with eating sugar extends to whatever food is paired with it, including vegetables.

Flavor-flavor learning accounts for how adults learn to drink black coffee, she adds: They begin by counteracting the bitter taste of the coffee with sugar and cream, then eventually learn to like the beverage without either enhancement.

But using sweets as a reward to children for eating something they don't like "is the absolute worst thing" parents can do, she insists.

"What that does is teach the kid to dislike vegetables and to like dessert; it's completely reverse of what parents think they're doing," Capaldi says.

This strategy produces a contrast effect. "Compared to dessert, string beans aren't that 'good,'" she says, noting that when rats are given rice followed by sucrose, they don't learn to like rice.

Flavor-flavor learning only works if flavors are mixed together, or at most separated by a seven-second delay, she says.

But if you mix the string beans into the dessert, flavor-flavor learning kicks in, and kids will learn to like the beans, even after the dessert is taken away, she maintains.

And once a taste preference is set, it doesn't go away-unless, of course, you mix the beans with a taste the child doesn't like, she adds.

"Once you've learned something like this, you will eat more, and if you eat more of it, you will like it.

"All you have to do is get them (kids) to eat it (the vegetables)," she says, noting that at that point, it will become part of their eating routine.

Capaldi, who has edited two books on the psychology of eating and authored the chapters on taste preferences, points out there are other ways besides flavor-flavor learning to determine food preferences. One is by mere exposure-by eating the same thing over and over "it becomes familiar and you come to like it more," she says.

Take, for example, skim milk. Most people find it watery when they first start drinking it. Yet after awhile, the taste is not so bad, and whole milk will seem too rich, she says.

But it can take two to four months for a person to learn to like a particular food. "And most of us are not that patient," she notes.

This familiarity effect also produces a mechanism that leads us to eat a variety of foods, she adds, joking that even she couldn't eat spaghetti every day because "you get tired of a particular taste."

"If I give you only bananas, how many bananas could you eat, no matter how hungry you are?" she asks. "Part of the reason we eat.is food tastes good and it's a sensory pleasure; it's fun to eat."

The more variety in a meal, the more you'll eat, she says.

"If I give you bananas and bread, you could eat more. And if I give bananas and bread and chocolate, you could eat a whole lot more."

Most diet plans are based on this concept, she says.

"They say to eat only 'x.' It really doesn't matter what 'x' is, if you can only eat 'x,' you will get tired of it and you will eat less," she says, recalling the cabbage soup diet fad.

Capaldi says another way of determining preferences, called taste-aversion learning, involves pairing a particular taste with an unpleasant experience. For example, becoming ill after eating a particular food will lead to an aversion to that food, a tactic, she points out, that she does not recommend.

Yet another way, flavor-nutrient learning, involves pairing a taste or flavor with nutrients-calories-to increase liking for that food.

Genetics, she says, play a role in this type of learning. In order to survive, animals learned to eat foods that are higher in calories, and humans "do the same thing. We're genetically built to go for the high fat-it makes us feel fuller faster," Capaldi says.

And pairing fat and sweet is "the magic combination," she says.

Take a brownie-a tasty treat that is full of sugar and fat.

Since sugar makes you like whatever you're eating it with, "when you eat a brownie, you're teaching yourself to like fat," she says. And sugar masks the taste of fat, so you don't realize what you're eating.

Moreover, fat makes sugar taste better because it produces something called "mouth feel," she says.

So, what can we do to eat better?

The good news, Capaldi says, is that we can get used to different levels of sugar and fat in our diet. And "once you go low enough (in sugar, fat or even salt), you get used to it, and you can't go back (to the higher levels).

"Every time you eat, you're giving yourself a learning trial, training yourself to prefer something," she says. "You can teach yourself better eating habits. It just takes a lot longer to get it to taste good than you might be willing to wait."

Capaldi's work this semester has focused on taste-smell. The basic finding, she says, has been that "actually, we can smell the taste."

Rats can learn to like or dislike salt by their experiences, even if they don't eat it.

"They smell it. And the same for saccharin-they can smell it and learn about it by smell," she says, calling the finding "surprising."

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