Evaluation of solid state of rice flours produced by different milling processes using ATR-FTIR spectroscopy

This study evaluated the influence of the milling process on solid state
of rice flours according to water activity using ATR-FTIR. A band at 1740
cm-1 attributed to the C=O stretching of lipids was detected for
crystalline samples, and it disappeared at a high aw range. The CH band at
2930 cm-1 of crystalline samples gradually shifted to a higher wavenumber
with aw. This band of the α-formed and wet-milled samples shifted to
higher wavenumbers above 0.8 aw. A band due to OH stretching mode in the
3500–3000 cm-1 region did not shift with aw. The result obtained from IR
spectra suggests that the parameter K calculated by Guggenheim–Anderson–de
Boar (GAB) model reflected not only the interaction between water
molecules but also the changes of state in solids. Consequently, the
results from this study provide insights about the adsorption properties
of non-ideal solids such as rice flour.