Now, Peterson and Moskowitz are challenging the dogma about what makes whole grain breads bitter and, consequently, less acceptable than processed white bread to U.S. consumers. In spite of its current vogue among the health-conscious, whole wheat flour sales are not rising as rapidly as once anticipated and even declined slightly in 2007 to just 3.9 percent of the total U.S. flour market. "My daughter is five" years old, Peterson says, "and I'm having a problem getting her to eat whole grain bread."
He's not the only one. A study conducted by flour-maker ConAgra and the University of Minnesota found that school-age children ate more of just about anything—pizza, breadsticks or tortillas—when they were made from refined rather than whole grain wheat flour. According to Elizabeth Arndt, ConAgra's manager of research and development, the consensus in the industry is that whole grain flour's flavor is a necessary evil: the health benefits of wheat are contained in the high-fiber bran, which is also loaded with a bitter-tasting phenol called ferulic acid, which acts as a crosslink in plant cell walls. The darker the bread, the more fiber it has, and the more bitter it is. ConAgra has started using a winter wheat in its Ultragrain whole grain flour, which is lighter in color and tasty enough to fool those same schoolchildren into thinking it is the refined variety.
But Peterson sees Ultragrain as an incomplete measure and thinks there's another, more fundamental solution to the bitterness problem that would work for any flour type. "The amounts of phenols are very low—and too low, I think, to make an impact," he says of the ferulic acid in bran, "The amount that's there—if I were to put it in water, I would find no bitterness." Instead, he says the phenols may interfere with the Maillard reaction, stunting the development of bread aromas, and triggering the production of many more compounds that are bitter on the tongue.
To test this idea, Moskowitz runs her vials of bread extract through what she calls "a big fancy oven." As the extract heats up, individual odors become airborne and pass through a threadlike tube, nearly 100 feet (30 meters) long. The instrument, called a gas chromatograph, measures the intensity of these aromas as they rise from the liquid and create the gas mixture known as the "headspace." Meanwhile Moskowitz places a tube up her nose and writes down her experiences over 45-minute sittings. Her lab notes are filled with columns of visceral, one-word descriptions: puke, glue, latex, nutty, onion, popcorn and butter.
"I wouldn't expect to smell mushrooms, dirt and cucumber," she says, "but when it comes together it smells like bread." So far, her lists for white and wheat contain the same subjective scent descriptions, but she says she has to dilute the extract to compare their intensities.
At the same time, Peterson tries to home in on the development of bitterness. He pulls up a graph that looks like a roller coaster with eight humps. In an experiment he ran weeks earlier, he yanked all the phenols from the whole wheat crust extract, and these eight humps represent the important flavor components left behind. He isolated each of these fractions, turned them into a powder, and tasted them.
"It's bitter," he says of fraction 4. "There are a couple others in here that have what I call a mouth-coating astringency, and they just stick to your tongue." There can be anywhere from 10 to 100 chemicals that make up each of these humps, and he'll have to partition them again to pinpoint the exact chemical. One thing is already clear, he says, "Bitterness is not coming solely from phenolic compounds...90 percent of it is coming from other molecules generated during thermal processing."
ConAgra's Arndt welcomes the new research and believes it could have wide-ranging implications in the food industry. "Anything we can do to make whole grain more universally acceptable to consumers," she says, "is a good thing."