Effect of temperature on the synthesis, composition and physical properties of potato starch
1999
Tester, R.F. | Debon, S.J.J. | Davies, H.V. | Gidley, M.J.
Potato tubers (cv Maris Piper) were grown at 10, 16, 20 and 25 degrees C in constant-environment chambers until maturity, whereupon the starches were extracted and subjected to rigorous chemical and physical analysis. The structure of the amylopectin molecules from the different starches postdebranching with isoamylase showed very little variation. The amylose and phosphorus content of the starches did show some variability while granule size tended to decrease as growth temperature was increased. There was, however, a marked increase in gelatinisation temperatures with a roughly constant enthalpy of gelatinisation as a function of growth temperature. The number of amylopectin double helices was determined by (13)C CPLMAS-NMR and crystallinity by wide-angle X-ray diffraction and in common with the enthalpy of gelatinisation found to be almost constant. It is proposed that the differences in the gelatinisation temperatures reflect enhanced registration of the amylopectin double helices in crystallites which restricts hydration and hence elevates gelatinisation temperatures. This is probably associated with enhanced rigidity of amorphous regions. The consequence of these ordering effects is that sweding is restricted, even if there is no detectable order by DSC (post-T(c)), because of steric hindrance to hydration exerted by the closer proximity/improved registration of the amylopectin chains.
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