From his food engineering lab at the Center for Excellence in Post-Harvest Technologies (CEPHT), Guibing Chen, Ph.D., is on a quest to improve the nutrition and quality of high-fiber bread and baked goods.
It isn’t uncommon for visitors to Guibing Chen, Ph.D.’s food engineering lab to be greeted by the appetizing aroma of baking bread. It’s a humble, homey scent and makes an odd contrast to the shiny beakers and the bustle of white-coated lab assistants.
But it’s all in a day’s work for Chen and his team. They are intent on finding new ways to enhance bread and baked goods that not only yield terrific taste and texture, but improve human health into the bargain. Chen’s main focus is on processing bran fiber to make it more palatable, nutritious and easy to incorporate into baked products, without affecting taste or shelf life. The process could add value to food industry products.
On this day in early September, Ph.D. student Yun Wu is comparing a standard-recipe loaf of white bread with one that has been enriched with 20% corn bran. As he lifts the loaves from the bread baking machines, Wu explains he is gathering data on how adjustments to the amount of water and bran affect bread quality. He examines the 20% bran loaf, which lacks the uniform loft of the other, and shrugs.
“It could be better,” he says.
And how does it taste? That remains to be seen. Although the recipes tested here use edible ingredients, the lab is not certified for food production or sensory testing. Each bread making machine sports a label in bold black type reading “Not for Human Consumption.” Still, much can be learned with instruments that measure density, texture, nutrition and other properties. Sensory testing by humans will have to wait until it can be conducted in an approved setting.
Wu is just one of several Ph.D. students Chen advises. Another of his students, Maria Ortiz de Erive, was a finalist in the graduate student research paper poster competition at the 2018 Institute of Food Technologists’ annual meeting, recognizing her research on high-fiber bread. The secret to her success was adjusting the water content and using a special process for corn bran that Chen is developing.
Why research bran?
There are good reasons for Chen’s focus on cereal bran. Not only is it an optimal source of fiber, but it also contains much of the nutrition found in grains. Fiber is something nutritionists say most of us need more of, but few of us consume as much as we should.
According to the Institute of Medicine, women are advised to get 25 grams of dietary fiber per day, a little over 8 teaspoons. For men, it’s 38 grams, about 12 teaspoons.
Considering that a cup of cooked brown rice or a medium apple each contains only about 4 or 5 grams of fiber, it’s easy to see why many of us eating the standard American diet have trouble getting the recommended amount.
Then there’s the fact that bran fiber poses a challenge for the food industry. Bran makes baked goods heavy, dense and gritty. It also turns rancid quickly, imparting “off” flavors and shortening shelf life. All of which are turn-offs for consumers and producers alike. And that’s why most baked goods are made from white flour, which has been milled to remove the outer bran layer.
White flour performs well in recipes, is shelf stable, and is popular for its mild taste and smooth texture. Unfortunately, white flour also is implicated in diabetes and obesity. It’s mostly starch and has a high glycemic index, causing blood sugar to spike.
Bran happens be the component in grains where micronutrients reside. It’s packed with most of the vitamins, minerals, antioxidants and disease-fighting phytochemicals that exist in grain. It also has physical properties that make for good digestion. Everyone agrees it’s a shame all that goodness gets subtracted from flour, but when it comes to consumer satisfaction, fluffy and soft usually win out over heavy, dense and gritty.
Mindful of bran’s healthful properties, the food industry has grappled with ways to process it so that it can pass muster with consumers. They treat it with enzymes, or pulverize it with mills or grinders, or compensate for bran’s heaviness by adding more gluten or gums to recipes, all with varying degrees of success.
Several years ago, Chen got interested in the quandary and wondered, what if there was an even better way to process bran? Could bran be made virtually undetectable to consumers and more healthful, while also performing well in recipes and lasting longer on the shelf without the need for additives?
The search for that synergy inspired his research, and he turned for an answer to an unconventional technology: microfluidization. It’s a technology more common to medical and nanotechnology research and rarely used in food engineering. Chen is pioneering this application.
Engineering bran
Microfluidization works by forcing a liquid stream containing solid particles or liquid droplets at high pressures through minute tubules with diameters similar to human hair. The extraordinary shear force breaks down the particles into micro- or even nanoparticles and changes the structure of materials of which the solid particles are made.
Microfluidization is a process more common to medical research than food science, but it has shown promise in improving cereal bran’s palatability, shelf life and health-related properties.
Chen used this technology on bran, finding that it loosened its structure and unlocked more of its nutrition. He extracted and analyzed the nutrient concentration, comparing it to that of unprocessed bran.
As expected, nutrients and antioxidants were significantly higher in the processed version. This was most likely due to the increased porosity and surface area of the particles, he said. Chen thinks the nutrients’ porosity should make them more bioavailable during digestion, and he plans to test that hypothesis in future studies. The higher concentration of antioxidants also might increase shelf life, considering they may slow down lipid oxidation, he said.
Along his research path, Chen also developed an answer to another issue inherent in commercializing microfluidized bran: the high amount of water it takes to force the material through the machine. A potentially expensive next step would be needed to reduce the moisture and get the right concentration. To solve the problem, he engineered a process for up to 20% bran in water, which yields a product that is ready to use in recipes.
“You could use it directly, with no dewatering,” Chen said, adding that the process easily could be scaled up for commercial applications, since some microfluidization machines can process hundreds of pounds of material an hour.
He has done similar microfluidization research with wheat and oat bran. Corn bran, which comes from the largest grain crop in the United States, was the logical next step. The research has potential to produce new products to improve human health.
Future steps
Chen’s published research demonstrates the threefold mission of CEPHT: to educate future food scientists, improve nutrition for consumers, and spur economic growth through value-added products and processes.
He said more avenues of research into processed bran will be explored as funds become available. He wants his next project to examine the role of bran in the microbiome, the ecosystem of bacteria in the human gut that plays an important role in overall health. He also hopes to conduct sensory testing and, finally, an economic analysis.
“We want to make a more powerful bread, with more bran, so you can eat the same amount but get more health benefits,” Chen said.
“You could get half your daily requirement in about 5 ounces of bread. Three or four slices. It isn’t hard to eat 5 ounces.”
