Effect of calcium and hydroxypropylation on crystallinity and digestibility of rice starches

✍ Scribed by Nurul Islam, Mohammad; Mohd Azemi, B M Noor

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 268 KB
• Volume: 76
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(199802)76:2<161::aid-jsfa918>3.0.co;2-6

✦ Synopsis

The digestibility of native and hydroxypropyl rice starches in the presence of calcium was investigated. Calcium interacted with native and hydroxypropyl rice starches and altered their relative crystallinity. Hydroxypropylation was measured in terms of molar substitution (MS) which in turn enhanced calcium binding. Depending upon the amount of calcium added (50È250 lg calcium per g dry starch) and levels of MS (ranging from 0É02 to 0É12), 25É4È 34É1 lg calcium was bound per g of hydroxypropyl starch. Native starch bound 25É4 lg calcium per g dry starch, which was much less than the hydroxypropylated starches. Crystallinity decreased with the increase of MS and calcium concentration. Digestibility of ungelatinised hydroxypropyl starches increased with MS (2É5È4É1 mg reducing sugar released per g dry starch) and the trend is reversed in the gelatinised form. Calcium-induced amylolysis of the starches by porcine pancreatic a-amylase but somehow inhibited amyloglucosidase attack.