Effect of Soaking on Wet-milling of Rice

National Taiwan University, Graduate Institute of Food Science and Technology, 59, Lane 144, Keelung Road, Section 4, Taipei, Taiwan
Journal of Cereal Science 01/2002; DOI: 10.1006/jcrs.2001.0419

ABSTRACT Soaking is an essential step in wet-milling of rice flour. The effects of soaking duration and temperature (5 and 25 °C) on the properties of rice flour have been investigated. The uptake of water by rice kernels increased with temperature and reached a plateau at about 30–35%. Protein, lipid, and ash leached out during soaking. The moisture content after soaking appeared to be a key factor on loosening the structure of rice kernels, which resulted in the production of small particle flours with little starch damage. The particle size of flours did not alter the gelatinisation temperature (Toand Tp) in DSC thermograms. Small particle and low lipid content flours appeared to have high peak viscosity measured by RVA. The change in microstructure of rice kernels during soaking was also examined by SEM.

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