Effect of the Amount and Particle Size of Wheat Fiber on the Physicochemical Properties and Gel Morphology of Starches

Abstract

Effects of added wheat fiber, with different levels and particle sizes, on the physicochemical properties and gel morphology of wheat starch and mung bean starch were investigated, using rapid visco analyzer (RVA), texture analyzer (TPA) and scanning electron microscopy (SEM). Each starch was added with wheat fiber at 10, 20, 30 and 40% (weight basis, g/100g), and different sizes of 60, 100 and 180 mesh, respectively. The peak viscosity (PV) of starches with wheat fiber were higher than the control. Starches had the highest PV with 40%, 60 mesh wheat fiber. The starches with wheat fiber showed higher hardness when compared to the control. Wheat starch and mung bean starch, with 40%, 60 mesh wheat fiber, had the highest hardnesses of 147.78 and 1032.11g, respectively. SEM showed that the dense honeycomb structure of starch gel was diminished with increasing wheat fiber. Additionally, the number of internal pores was reduced, and a large lamellar structure was formed.

Functionality-driven fractionation the need for mild food processing

“…Sun et al (2015) found a similar trend after the addition of fibers to a starch gel. Yet, the increase in hardness values when additional fibers were present was less substantial as the increase found by Sun et al (2015).…”

“…Sun et al (2015) found a similar trend after the addition of fibers to a starch gel. Yet, the increase in hardness values when additional fibers were present was less substantial as the increase found by Sun et al (2015). The cohesiveness value, representing the ability of a sample to retain its structure after compression (Yildiz et al 2013a), shows that all three starch gels were able to retain, to most extent, their structure and the deformation was non-destructive.…”

“…In other words, the mildly refined starch and the recombined starch fractions can be considered as a phase separated mixture, in which the water-binding of the fibers influences the effective starch concentration in the continuous phase, which leads to an increased viscosity. This conclusion is supported by Sun et al (2015), who found that the peak viscosity of starches to which wheat fiber was added, was significantly higher than the control where no fiber was added. The wheat fiber was found to have an even higher WBC than the starch, which explained the bigger effect in case of wheat.…”

“…These blends are currently created by blending highly refined ingredients, leading to illogical combinations. For instance, Sun et al (2015) blended highly refined wheat starch and fibres in different ratios. Understanding these interactions is important not only to improve the fractionation of raw materials but also to help explore possible synergistic effects with respect to the functional properties of partly fractionated ingredients.…”

“…The presence of non-starch polysaccharides affects these structural functionalities (BeMiller 2011). In literature, it is found that the pasting and rheological properties of several starch dispersions were significantly affected by the addition of apple pomace (Parra et al 2015), rice dietary fiber (Lai et al 2011), wheat fiber (Sun et al 2015) and oat, pea, lemon and apple fiber (Yildiz et al 2013a). The magnitude of this effect is related to the nature of the fibers and the extent of starch substitution (Collar et al 2006).…”