Changes in retrogradation properties of rice starches with amylose content and molecular properties
2004
Lii, C.Y. | Lai, V.M.F. | Shen, M.C.
The increases in storage modulus (G'), retrogradation enthalpy change (deltaH) and deltaH-related Avrami kinetic parameters of gelatinized rice starch dispersions at 25% (w/w) were investigated with respect to storage period, amylose content (AC), and molecular properties. Three high-AC and five low-AC rice cultivars were compared for understanding the multiple influences of AC and molecular properties involved. After refining the results of correlation analysis, the G' of just-cooled samples changed positively, mainly with AC and additionally with the average chain length of amylose (CL(AM)) and the weight ratio of extra-long plus long chains to short chains of amylopectin (AP) (r(APchain)). The developed deltaH on short-term storage (10 days) elevated with increasing AC and CL(AM) and decreasing degree of polymerization of AP (DP(AP)), but after long-term aging for one to three months with increasing r(APchain), especially for the low-AC cultivars examined. Greater Avrami rate constants for retrogradation could be attributed to the combination of a lower DP(AP) and r(APchain) or AP chain length and a greater CL(AM). The polynomials using these critical factors to describe the retrogradation parameters were elucidated and could account for 85-99.6% of data deviations.
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