The impact of extrusion processing on fortified breakfast cereals containing β‐glucan‐enriched flour: physical, structural, and nutritional aspects

This study evaluated the effects of various factors on breakfast cereals containing β-glucan-enriched flour fraction (BEFF). A central composite design (CCD) was used to examine the effects of BEFF level, screw speed, and die temperature on the physical, textural, microstructural, and nutritional properties of the cereals. The addition of BEFF initially increased the L* value by 5.1%, followed by a decrease at higher levels. Porosity increased linearly, whereas starch digestibility decreased. Screw speed was the most significant independent variable affecting the physical and structural properties of the cereals, followed by die temperature. The optimum processing conditions were 5.1% BEFF, 435 rpm screw speed, and 170 °C die temperature (with the other barrel zones maintained at 40, 50, 70, 90, and 100 °C), yielding β-glucan content of 14.3 g kg-1 and starch digestibility of 196.46 mg maltose g-1. β-Glucan loss was limited to 42% at most when compared with the unextruded blend. Extrusion increased starch digestibility and reduced β-glucan content, and the enthalpy of starch gelatinization tended to decrease with BEFF incorporation into the control sample. All breakfast cereal products in this study met Food and Drug Administration (FDA) requirements, containing at least 0.75 g of β-glucan per serving portion.