Effect of chemical modifications on the crystallinity of yellow corn, sordan, sorghum and pearl millet starches [Egypt]
1988
Abou-Arab, A.A. (Ain Shams Univ. , Cairo (Egypt). Faculty of Agriculture) | Mahmoud, R.M.
X-ray diffraction was used to examine the strength of associative bonding forces between starch chains for native and chemically modified yellow corn, sorghum, sordan and pearl millet starches. X-ray patterns showed that the proportion of retrograded or "B" structure was developed in all crosslinked and palmetic modified starches which was absent in all native starches. Moreover, both yellow corn and sordan cross -linked starches have also "C" structure. The intensity of "V" type which characterized the fat amylose complex was more pronounced in palmetic acid modified starches. The relative crystallinity of various chemically modified starches were also measured by X-ray diffractometer. The patterns showed that areas of crystallinity portions of all modified starches markedly higher than correspondings native starches. On the assumption that crystallinity of native starch is 1.0, that of palmetic containing yellow corn starch was 2.2. Cross-linking starch crystallinity and increase was higher in fatty acid modified starches than that of crosslinking.
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