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Characterization of the Pasting, Flow and Rheological Properties of Native and Phosphorylated Rice Starches
Author(s) -
Lin Qinlu,
Xiao Huaxi,
Zhao Jian,
Li Lihui,
Yu Fengxiang
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.200900184
Subject(s) - starch , rheology , retrogradation (starch) , shear thinning , swelling , viscosity , food science , chemistry , phosphate , phosphorylation , materials science , biochemistry , amylose , composite material
Phosphorylation of rice starch and its effects on the physiochemical properties of the starch were investigated. Phosphorylation was conducted using the oven heating method by heating mixtures of rice starch and monosodium dihydrogenphosphate at 120‐150°C for 0.5‐2 h, and the pasting, flow and rheological properties of the resulting starch phosphates were analyzed. Phosphorylation with substitution degrees of up to 0.12 was achieved by raising the reaction temperature to 140°C, but further increase in the temperature to 150°C caused a marked reduction in the degree of substitution. Phosphorylation resulted in significant declines in pasting temperature and setback, but increases in peak viscosity and breakdown. Suspensions of rice native starch and starch phosphates were shown to be non‐Newtonian, pseudoplastic fluids, exhibiting typical shear thinning. They also exhibited yield stress, the magnitude of which increased with the degree of phosphate substitution. Dynamic testing showed that phosphorylation resulted in a decrease in the temperature at which storage and loss moduli ( G ′ and G ″) reached a peak during heating and a reduction in G ′ during cooling. These results appeared to indicate that phosphorylation improved the shear stability of rice starch pastes and enhanced swelling of starch granules, but impeded starch retrogradation.