Effect of Dry and Wet Millings on Physicochemical Properties of Black Rice Flours

Abstract

The physicochemical properties of black rice flours produced from dry and wet milling were carried out to investigate their applications in food processing industry. The dry milled black rice flours showed lower fat, protein, ash, and anthocyanin contents than those of wet milled black rice flours with no effect due to number of millings. Average particle sizes (379～288 μm) of dry milled flours were bigger than those (336～253 μm) of wet milled flours. Particles with 60 mesh or more increased with increasing milling times. Wet milled flours had higher damaged starch, water solubility index (WSI), and water absorption index (WAI) compared to dry milled flours. Pasting properties measured by rapid visco analyzer (RVA) resulted in higher pasting temperatures in dry milled flours (62.5～69.4 o C) than wet milled flours (46.1～46.4 o C). As the number of milling times increased, pasting temperature of wet milled flours were not effected. Dry and wet milling resulted in reduced trough, final viscosity, and consistency with increasing milling times.

Rheological properties of rice flour treated with mild solutions of citric acid

“…The setback value representing the degree of retrogradation for wetmilled rice flour was 124.2 RVU and that of dry-milled flour was 114.7 RVU. Previously, dry-milled black rice flour was shown to have a higher peak viscosity, trough, and final viscosity than those of wetmilled black rice flour (13). On the basis of the particle size and viscosity results, we conclude that differences in milling conditions may lead to changes in particle size, which ultimately influences the RVA results.…”

“…Preparation of dry-and wet-milled rice powder, and particle-size determination Wet-milled rice flour was prepared by soaking rice in distilled water for 8 h followed by drying at room temperature for 1 h and milling with a roll mill (KM-18; Kyungchang, Seoul, Korea) (13). Dried wet-milled rice flour was sealed in a plastic bag and stored at 20…”

Agronomic and genetic analysis of Suweon 542, a rice floury mutant line suitable for dry milling

“…In wet milling, the quality of rice flour is improved by reducing flour particle size as well as damaged starch content through soaking procedures. However, the production costs are high because of the additional expenses associated with the disposal of waste water, sterilization and drying of the wet flour (Altheide et al 2012 ; Jun et al 2008 ; Kim et al 2009 ; Lee and Kim 2011 ). Recently developed technologies such as jet milling and cryogenic milling also require expensive investment and production (Ashida et al 2010 ; Tran et al 2011 ).…”