Functional Properties of Submicron‐Scale Rice Flour Produced by Wet Media Grinding

Abstract

Cereal Chem. 93(1):53-57The digestibility and hydration properties of wet-ground submicron-scale rice flour were compared with those of dry-ground coarser microscale flours. The submicron flour (mean size 0.6 µm) was produced in a wet-media mill with 0.3 mm zirconia beads by continuous 24 h pulverization. The solubility, water absorption index, and swelling power increased as the mean particle size decreased, reaching maximum values in the submicron flour.Starch damage was high in the submicron flour, with the absence of intact starch granules. The digestibility also increased as the particle size decreased, and it was highest in the submicron flour. These results show that wet-ground submicron rice flour has different functional properties from dry-ground coarser flour. The digestibility was more strongly influenced by starch damage and the water absorption index than by the mean particle size.

Mechanically and Thermally Induced Degradation and Modification of Cereal Biopolymers during Grinding

“…Thus, the accessibility and surface/volume ratio of particles significantly affect the SMD. The fragmentation of particles leads to the enlargement of the particle surface, which in turn promotes the digestion by enzymes [5,29,30]. This negative correlation between the particle size distribution and the starch modification degree (SMD) was also confirmed in the present study: while an exclusively thermal treatment of starch and flour did not result in an enhanced starch modification degree (SMD) and or the shift of PSD to smaller sizes (Figure 4A), mechanical treatments with/without thermal forces (MS and TMS) led to a decrease in particle size of wheat flours and an increase in SMD (compare Figure 4B), which is in agreement with other studies, analyzing the effects of grinding on starch modification and particle size [31,32].…”