By Xue Si-Ying, bakery application specialist
Our bakery experts test soluble and insoluble fibers in toast bread and Asian sponge cake.
Wherever there’s bread, there’s typically a consumer preference for white bread with a low fiber content. According to Leatherhead Research International, around 70% of the bread consumed in many countries is still white, despite widespread recognition of the need for more fiber in the diet.
At DuPont, we’ve invested a lot of research in developing ways to add fiber to bakery products without altering their soft, white characteristics (you can read about that in the previous issue of Bakery Performance - The Health Issue).
Mixing soluble and insoluble
Another aspect of fiber addition that interests us is the composition of the fibers added to bread and cakes. Nutritionists agree that we all need a combination of soluble fibers, which stimulate the growth of a healthy microflora in the intestine, and insoluble fibers, which support fecal transit.
The problem bakery manufacturers face is that, when they attempt to incorporate sufficient soluble and insoluble fibers into their products to qualify for a high-fiber claim, the fibers have a negative impact on structure and sensory quality.
In our bakery lab, we have conducted several trials with soluble and insoluble fiber addition to toast bread and Asian sponge cakes. The soluble fiber we have used is polydextrose. Soy fiber was the insoluble component.
Better volume and softness
Previous trials had already shown us that the use of polydextrose and specialty cellulose gum could improve volume, softness and resilience in a high-fiber, white toast bread. When we combined polydextrose addition with soy fiber, we found that the volume and sensory quality were even better. Compared to the control, bread softness was improved over a 14-day shelf life.
Similar work in Asian sponge cakes first looked at whether a high dosage of polydextrose, for example 6%, could actually directly replace some of the flour. The result here, however, was that the final cakes were low in volume and had a poor crumb texture. Recipe supplementation with 6% polydextrose in addition to the other ingredients, on the other hand, had a far more positive outcome – an acceptable volume and improved crumb.
Our next step was to test the sponge cake recipe with a combination of polydextrose and soy fiber. As we experienced in our bread trials, this added further to the sensory quality. Both moistness and crumb softening were evaluated as being comparable to the control recipe without added fiber.
No limits on quality
This tells us is that the addition of soluble and insoluble fiber combinations is more likely to enhance than limit the quality of high-fiber baked products aimed at consumers with a preference for white bread. All you need is the right proportion and choice of ingredients and a few minor processing adjustments.
Let us know if you are interested in learning more. You can also read the Bakery Performance article on Middle East and Africa markets here.