Milling of rice grains: The roles of starch structures in the solubility and swelling properties of rice flour
Rice flours with different particle sizes and degrees of damaged starch granules were produced by hammer milling and cryogenic milling of rice grains, where degradation of starch molecules was evident in the hammer‐milled flours, but not in the cryogenically milled flours. The solubility and swellin...
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Published in | Die Stärke Vol. 64; no. 8; pp. 631 - 645 |
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Main Authors | , , |
Format | Journal Article |
Language | English French German |
Published |
Weinheim
WILEY-VCH Verlag
01.08.2012
WILEY‐VCH Verlag Wiley Wiley Subscription Services, Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Rice flours with different particle sizes and degrees of damaged starch granules were produced by hammer milling and cryogenic milling of rice grains, where degradation of starch molecules was evident in the hammer‐milled flours, but not in the cryogenically milled flours. The solubility and swelling properties of the resulting rice flours were determined in cold (30°C) and hot water (90°C). The cold‐ and hot‐water starch solubility was strongly correlated with the degree of damaged starch granules, and weakly with the particle size of rice flour. No evident correlations were observed between starch solubility and the molecular structures, indicating that molecular degradation by milling process was not the only precondition of increased starch solubility. Possible mechanism for the observed correlations is that increasing surface area and/or exposure of loosely packed inner part of starch granules with increasing degree of damaged starch granules allowed more starch molecules to leach out in cold and hot water. Furthermore, the cold‐water swelling of rice flour was strongly correlated with the degree of damaged starch granules, possibly due to the rapid hydration of damaged starch granules, whereas the hot‐water swelling did not show any correlations with flour particle size and granular and molecular starch structures. The results have provided better insights in the relationship between starch structures and solubility and swelling properties of rice flour, which can be used to improve the manufacture and selection criteria of rice flour for better products. |
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Bibliography: | ark:/67375/WNG-F8T4GFTG-Z istex:1B15FF6513EE2236CB45ECDBC7370476D85903B8 Australian Research Council - No. DP0985694; No. LP0990769 ArticleID:STAR201100204 Colour online: See the article online to view Figs. 1 and 3 in colour. Colour online See the article online to view Figs. 1 and 3 in colour. |
ISSN: | 0038-9056 1521-379X |
DOI: | 10.1002/star.201100204 |