Premium
Dynamic Rheological and Thermal Properties of Acetylated Sweet Potato Starch
Author(s) -
Lee HyeLin,
Yoo Byoungseung
Publication year - 2009
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.200800109
Subject(s) - differential scanning calorimetry , starch , dynamic mechanical analysis , rheology , dynamic modulus , acetylation , retrogradation (starch) , enthalpy , materials science , glass transition , potato starch , chemistry , food science , composite material , thermodynamics , biochemistry , amylose , polymer , physics , gene
Dynamic rheological and thermal properties of acetylated sweet potato starch (SPS) pastes (5%, w/w) were evaluated as a function of the degree of substitution (DS). The transition temperatures ( T o , T p and T c ) and enthalpy of gelatinization (Δ H ) of acetylated SPS, which were determined using differential scanning calorimetry, were lower than those of native starch, and significantly decreased with an increase in DS. Magnitudes of storage modulus ( G ′), loss modulus ( G ′′) and complex viscosity (η*) of acetylated SPS pastes were determined using a small‐deformation oscillatory rheometer. Dynamic moduli ( G ′, G ′′ and η*) values of acetylated SPS pastes except for 0.123 DS were higher than those of native starch, and they also decreased with an increase in DS. The tan δ (ratio of G ′′/ G ′) values (0.37–0.39) of acetylated SPS samples were lower than that (0.44) of native starch and no significant differences were found among acetylated SPS samples, indicating that the elastic properties of SPS pastes were affected by acetylation but did not depend on DS. The G ′ values of acetylated SPS during aging at 4°C for 10 h were much lower than those of native starch, showing that the addition of acetyl groups produced a pronounced effect on the retrogradation properties of SPS.