The tantalizing aroma of freshly baked brioche is hard to resist, while a virtuous loaf of whole wheat often lacks that same allure. Blame it on the ferulic acid.
See, whole-wheat bread contains all parts of the wheat, including the bran, but white bread does not. That bran in the wheat bread contains the aforementioned ferulic acid, which overrides the compounds that give white bread its mouthwatering smell, according to new research.
Much nudging from the health police has convinced more people to eat whole-grain bread, but just 60 percent of Americans eat a whole-grain food at least once in two weeks, according to the Whole Grains Council. Clearly our hearts, and our palates, still belong to white.
"My children, they cut off crusts from wheat bread. Why?" asks Devin Peterson, co-director of the Flavor Research and Education Center at the University of Minnesota. He knows he's not the only parent who's noticed that whole wheat can be a tough sell.
But unlike the rest of us, Peterson has the chops to figure out what makes for whole wheat's lack of appeal. His lab baked up whole wheat and white bread, removed the crust right when it came out of the oven, and froze the crust in liquid nitrogen.
After that Peterson and his colleagues ground the frozen bread crust in a mortar and pestle, added solvent, distilled the liquid, and ran it through a series of gas chromatographs and sniffers. (Crust was chosen because it's the part of bread that browns the most, and browning is a major part of flavor.)
The white bread crust gave off chemicals that smell like corn chips, potatoes, caramel, and flowers, while the whole wheat produced malty, earthy, cucumber, fatty smells. Which would you choose for toast?
To combat some of these issues, manufacturers often add salt and sugar to whole-grain bread. But that takes away from its nutritional value. Indeed, some products labeled "whole grain" have more sugar and calories than products that don't sport that label, a recent study in the journal Public Health Nutrition found.
Products with the Whole Grain stamp, which is a common symbol on food packages these days, were higher in fiber and lower in trans fats than some other foods, but had more sugar and calories compared to products without the stamp. Researchers from the Harvard School of Public Health found that products that met the American Heart Association's standard — requiring a 10:1 ratio of carbohydrates to fiber — were healthiest overall.
The Whole Grains Council, which developed the stamp, took some issues with Harvard's conclusions. "It's designed to address whole grain content and nothing more," says Cynthia Harriman, director of food and nutrition strategies for Oldways and the Council. And, she noted: "Whole-grain consumption went up 20 percent in the first three years after [the stamp] was introduced in 2005."
Still, more of us could stand to gain from the well-documented health benefits of whole grain, so figuring out how to make it yummier while still being healthy would be a big plus for the many people who have yet to make the switch.
In Peterson's quest for better whole-grain taste, he found that ferulic acid in wheat bran blocked production of d-2, a molecule that helps produce a warm, browned smell we associate with white bread. "If I were to give you this compound in pure form, it's very discernible," Peterson told The Salt. "It's a very nice baked note."
Chefs call that nice baked note the Maillard reaction, after a Frenchman who realized a century ago that it's what gives grilled steak and browned bread its rich flavor. (NPR's Joe Palca gives the lowdown on Maillard and how deliciousness can come from heating a mixture of sugars and amino acids.)
Bitter taste is also a problem for whole-wheat bread. Peterson has looked into that, too, and says the problem is not in the flour but in compounds created in fermentation and in the Maillard reaction. In the past, bakeries have tried different forms of flour to reduce bitterness, but Peterson thinks the solution lies in tweaking the proofing and baking process instead.
Removing ferulic acid from whole-wheat bran isn't the answer, Peterson thinks; he speculates that it may have health benefits. "You have to look at the whole picture and keep the good elements together."
He hopes that by figuring out just what makes whole-wheat bread taste and smell the way it does will help food manufacturers how to keep the nutritional goodness of whole grains, without losing the rich brown smell of freshly baked bread. Peterson's research was published in the Journal of Agricultural and Food Chemistry.