Study on the Change in Powder Properties of Rice Flour by Different Milling Processes

Abstract

The aim of this study was to clarify the change in the powder properties of rice flour depending on the milling process. Rice flour samples, which have gradual mechanical shock properties, were prepared using different milling methods. Furthermore, the correlation between the starch damage, owing to mechanical shock, and powder properties of rice flour was investigated. The particle size was changed gradually through each milling process; however, the change did not clearly correlate with starch damage. The results of the X-ray diffraction (XRD) pattern of nongelatinized samples showed the typical A-type structure of starch. The crystal structure of starch in rice flour may change to a disorder state with the progress of milling; thus, in this study, instead of crystallinity, we considered the disorder index (DI) calculated from the XRD intensity of samples. Relationship between DI and starch damage was confirmed with R 2 = 0.923. Therefore, the mechanical shock caused by the milling process contributes to the crystal state of starch. The parameter q m calculated from the Guggenheim-Anderson-de Boer (GAB) equation of each sample corresponded to the DI. This result suggested that the sorption site of rice flour decreased, and a positive correlation was observed between the parameter K and DI. Thus, the interaction between the rice flour and water molecules weakened because of the mechanical shock. In addition, the use of a SEM image supports the insight that the change in parameter K may reflect the structural change in the solid phase. These results demonstrated that the change in powder properties of rice flour caused by mechanical shock of the milling could evaluate quantitatively.

Quantification of Starch Order in Physically Modified Rice Flours Using Small-Angle X-ray Scattering (SAXS) and Fourier Transform Infrared (FT-IR) Spectroscopy

“…The ''a-formed'' sample was also prepared, and the white rice was subjected to a-type milling at 130 C. The sample preparation method was the same as that used in our previous study. 13 Small Angle X-ray Scattering Small-angle X-ray scattering (SAXS) in the 0.06-4.00 of 2y range was measured using a Smart Lab (Rigaku Co.) with 0.01 intervals of 2y. The tube current and X-ray voltage were 200 mA and 45 kV, respectively.…”

“…12 Indeed, the changes in the surface of starch particles in rice flour were reported through scanning electron microscopy in our previous research. 13 Nevertheless, the ambiguity of the structure of starch in rice flour constrains the interpretation of its solid state, and thus structural models in non-thermal processing, such as milling and water sorption, are still under investigation.…”

Phenomenological analysis on whipping behavior of rice flour batter

“…Shoji et al (2012) also found that the hydration behavior is closely related to the internal structure of rice flour. Moreover, Ishikawa et al (2017) demonstrated that adsorption properties might affect the internal structure and showed the potential of developing optimally controlled rice flour production based on mechanical shock in the milling process. However,…”

“…Moreover, Ishikawa et al. (2017) demonstrated that adsorption properties might affect the internal structure and showed the potential of developing optimally controlled rice flour production based on mechanical shock in the milling process. However, precise analysis of the process control methods for rice flour production is still needed.…”