December 31/Food & Farm Week -- According to recent research published in the International Journal of Food Science and Technology, "Five dietary fiber-rich ingredients were used at 5%, 10% and 15% replacement levels in a white flour cereal base to produce an extruded cereal product. The inclusion of the dietary fibers into the flour bases had no significant effect on the expansion ratio of the products.

"However, the bulk density of the extruded products increased with inulin addition. The pasting properties of the raw flour and fiber base, as well as the extruded products were altered with the incorporation of dietary fiber, with guar gum enriched products showing elevated peak and final viscosity readings. This appeared to be related to moisture manipulation and hence the regulation of gelatinisation. In vitro starch hydrolysis of the raw bases and the extruded samples illustrated that the extrusion process significantly increased the availability of carbohydrates for digestion. Additionally, the inclusion of dietary fibers in the raw bases significantly reduced the rate and extent of carbohydrate hydrolysis of the extruded products," wrote M.A. Brennan and colleagues, Massey University.

The researchers concluded, "As such the addition of dietary fibers to extruded products reduced the amount of readily digestible starch components of breakfast products, and increased the amount of slowly digestible carbohydrates."

Brennan and colleagues published the study in International Journal of Food Science and Technology ("Effect of inclusion of soluble and insoluble fibres into extruded breakfast cereal products made with reverse screw configuration." International Journal of Food Science and Technology, 2008;43(12):2278-2288).

For additional information, contact M.A. Brennan, Massey University, Institute Food Nutrition & Human Health, Palmerston North, New Zealand.

From the January 5, 2009, Prepared Foods e-Flash