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Phase and State Transitions in Granular Starches Studied by Dynamic Differential Scanning Calorimetry
Author(s) -
Liu Yayun,
Shi YongCheng
Publication year - 2006
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.200500448
Subject(s) - differential scanning calorimetry , glass transition , amorphous solid , starch , granule (geology) , annealing (glass) , materials science , phase transition , dynamic mechanical analysis , chemistry , chemical engineering , crystallography , thermodynamics , polymer , composite material , organic chemistry , physics , engineering
Phase and state transitions of granular starches heated in water are studied by dynamic differential scanning calorimetry (DDSC). The DDSC results of various granular starches show a stepwise heat capacity ( C p ) change in the storage C p curve, which starts at the beginning of melting or immediately preceding gelatinization and ends before the melting reaches its peak temperature. Annealing reduces the magnitude of this stepwise change in storage C p . After the amorphous phase is selectively removed by acid, the stepwise storage C p is greatly reduced. The stepwise storage C p increase is not observed when recrystallized linear short chains from enzyme‐debranched waxy maize starch are heated in water. The results show that the stepwise change in C p observed on the granular starch is a unique property associated with the phase transition of granular structure and reflects a glass transition of the rigid amorphous regions in starch granules. The glass transition of the mobile amorphous phase in granular starch is believed to extend over a broad range of temperatures before gelatinization. A small glass transition below 0°C is directly detected by DDSC and is attributed to part of the mobile amorphous fraction in granular starch.