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Relationship of Gelatinization and Recrystallization of Cross‐Linked Rice to Glass Transition Temperature
Author(s) -
Chatakada Pathama,
Varavinit Saiyavit,
Chinachoti Pavinee
Publication year - 2000
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem.2000.77.3.315
Subject(s) - chemistry , differential scanning calorimetry , amylopectin , starch gelatinization , starch , glass transition , recrystallization (geology) , retrogradation (starch) , enthalpy , melting temperature , swelling , chemical engineering , food science , thermodynamics , organic chemistry , polymer , materials science , amylose , composite material , paleontology , physics , biology , engineering
Nonwaxy rice starch was cross‐linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross‐linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross‐linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross‐linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross‐linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature ( T g ) measured from the derivative curve of heat flow was ‐3 to ‐4°C. No significant change in T g was observed over the storage time studied.