Physicochemical and Functional Characteristics of RD43 Rice Flour and Its Food Application

Abstract

The increased use of a new rice cultivar is the result of increasing consumer demands for healthier choices. In this study, physicochemical, thermal, pasting, and functional properties of flour from RD43 rice, a new rice variety, and its food application were investigated. RD43 rice flour demonstrated an irregular and polyhedral shape with a volume mean diameter of 103 ± 0.15 µm. In addition, the amylose content of RD43 rice and Hom Mali rice flour was 19.04% and 16.38%, respectively. The X-ray diffraction (XRD) and Fourier Transforms Infrared (FTIR) confirmed the presence of a V-type crystalline structure and less crystallinity in RD43 rice flour, which resulted in a significant reduction of the water absorption index (WAI), swelling power (SP), water solubility index (WSI), gelatinization temperature, and pasting properties. Comparing with Hom Mali rice flour, RD43 rice flour had greater ability to disrupt cholesterol micellization and bind bile acid. Furthermore, it had lower starch digestibility, with a lower percentage of rapidly digestible starch (RDS) and higher percentage of undigestible starch than Hom Mali rice flour. Moreover, steamed muffins based on RD43 rice flour had lower starch digestibility than Hom Mali steamed muffins. The sensory analysis showed no significant differences between Hom Mali and RD43 steamed muffins. The findings suggest that RD43 rice flour could be an alternative ingredient for lowering the glycemic index of food products.

Keywords: RD43 rice; bile acid binding; cholesterol micellization; muffin; physicochemical properties; starch digestibility.

Figure 1

Photographs of (a) Hom Mali rice flour, and (d) RD43 rice flour. Scanning electron micrographs of Hom Mali flour, magnified (b) 100× and (c) 1500×, as well as RD43 rice flour, magnified (e) 100×, and (f) 1500×.

Figure 2

The particle size distribution by volume of rice flour.

Figure 3

X-ray diffraction pattern of (a) Hom Mali and (b) RD43 rice flour. Fourier transform infrared (FTIR) spectra of (c) Hom Mali and (d) RD43 rice flour.

Figure 4

Pasting properties pattern of Hom Mali and RD43 rice flour.

Figure 5

The glucose release during in vitro starch digestion from (a) rice flour, (b) incremental area under the curve (iAUC) of glucose, (c) starch fraction, and (d) total starch of Hom Mali and RD43 rice flours. Data are expressed as mean ± standard error of the mean, n = 3. * p < 0.01 compared to Hom Mali rice flour. RDS: rapidly digestible starch, SDS: slowly digestible starch.

Figure 6

Photographs of (a) rice flour steamed muffin (left: Hom Mali steamed muffin, right: RD43 steamed muffin). (b) The glucose release during in vitro starch digestion from rice flour muffins, and (c) incremental area under the curve (iAUC) of glucose. Data are expressed as mean ± standard error of the mean, n = 3. * p < 0.01 compared to Hom Mali steamed muffin.

Figure 7

Sensory analysis of Hom Mali and RD43 rice steamed muffin. Data are expressed as the mean.