Molecular structure, rheological and thermal characteristics of ozone-oxidized starch
2011
Chan, Hui–Tin | Leh, Chiu Peng | Bhat, Rajeev | Senan, Chandra | Williams, Peter A. | Karim, Alias A.
The effects of oxidation by ozone gas on the molecular structure, rheological and thermal properties of starch (corn, sago and tapioca) were investigated. Starch, in dry powder form, was exposed to ozone for 10min at different ozone generation times (OGTs). Average molecular weight decreased in oxidized corn and sago starches but increased in oxidized tapioca starch. All oxidized starches exhibited non-Newtonian shear-thinning behaviour. Starch viscosity decreased drastically with increasing OGT. Young’s modulus for all oxidized corn and sago starch gels stored for 1 and 7days at 4°C increased significantly compared to unmodified starch. No differences were noted in gelatinization temperatures and gelatinization enthalpies of all oxidized starches compared to unmodified starch. Retrogradation enthalpy increased markedly in corn starch after 1min OGT. These results show that the extent of starch oxidation varies among starches of different botanical origins under similar ozone treatment conditions.
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