Not just quantity: Nofima says think about fiber quality

12-Nov-2015 - Last updated on 14-Nov-2022 at 15:52 GMT

Is the manufacturing process harming fiber quality?

There’s frequently talk that consumers aren’t getting enough fiber in their diets; but are they simply not getting the best quality fiber?

Research from Norwegian food research institute Nofima argues the quality of fiber in cereal, snacks and food might be as important as the quantity.

Nofima scientists Anne Rieder, Svein Halvor Knutsen and Simon Ballance are researching dietary fiber and the healthy aspects of cereal through projects such as Optifiber and OatMet. One aspect of the research is currently looking at how beta-glucan, which helps with the formation of viscous solutions in the small intestine, is affected by bread production.

“There is a general increased awareness that fiber is not like fiber,” Rieder told BakeryandSnacks. “There are differences in their chemical, physical and biological properties.”

Differences known, but may not be recognized

The differences between fibers are numerous, according to Rieder. For example, viscous fibers like beta-glucans are linked to slower nutrient updates from the small intestine with a positive effect on blood sugar regulation and cholesterol levels, while insoluble fibers like cellulose are linked to increased fecal bulk and decreased intestinal transit time.

Fibers have diverse properties, she said, but also experience both positive and negative changes during processing. Beta-glucans from oats or barley may see a decrease in molecular weight during processing, something that affects their solubility. Rieder said weight and solubility are important to form a viscous solution in the intestine, which benefits blood sugar and cholesterol levels.

“Some manufacturers are aware of this and want to know more about how to preserve the positive properties of beta-glucans during processing,” Rieder said. “However, in Europe the only criteria for the use of a health claim on cereal beta-glucans is the amount in the product and not the quality of the beta-glucan in the end product."

Cutting down on baking time

While beta-glucans won’t disappear during manufacturing, their degradation can be “dramatic” depending on the type of processing in bread, cereal and other gluten-based foods.

Baking usually has the largest effect on the fiber, as dough kneading and fermentation can impact the beta-glucan in wheat, barley, oat and ry.

“Decreasing the contact time by shortening the process (short fermentation times) or incorporating the beta-glucan containing ingredient at the latest possible time point (just before pan proving for example) will help,” she said. “Standard extrusion, on the other hand, has little impact on the molecular weight of beta-glucan and may even increase solubility.”

Improving as manufacturers and consumers

Nofima uses a customized high performance liquid chromatography (HPLC) process for detection, but she doesn’t believe this type of analysis will become common across the industry. Instead, she believes many organizations will set up a method based on viscosity measurements to help give an indication of beta-glucans’ nutritional quality.

Many small scale manufacturers are already speaking with Nofima about baking course and asking questions about fiber and beta-gluten, she said. However, many consumers across the world still fall well short of reaching dietary recommendations of fiber intake.

“Even though too low fiber intake may still be the biggest problem in the population, we have to start thinking not only about fiber quantity but also about fiber quality,” she said.