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Viscoelastic Properties of Gelatinized Dispersions of Maize Starch Modified by Solid‐State Milling
Author(s) -
Kochkitaliya,
Khokhlova Yuliya
Publication year - 2016
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-11-15-0219-r
Subject(s) - rheometry , starch , viscoelasticity , chemistry , rheology , viscosity , dynamic modulus , chemical engineering , dynamic mechanical analysis , amylopectin , solid state , amylose , materials science , composite material , organic chemistry , polymer , engineering
Solid‐state milling is an effective physical modification method applied to improve functional properties of starch. In this work the effect of solid‐state milling on the viscoelastic characteristics of maize starch gelatinized dispersions (gels) was investigated by using oscillatory squeeze film rheometry. The relaxation spectrum of the samples under study was calculated from the data obtained. It was found that solid‐state milling resulted in a decrease of the storage ( G ′) and loss ( G ″) moduli; meanwhile, loss tangent (tan δ) increased. At a starch milling time more than 10 h, G ″ > G ′ and the gelatinized starch dispersions behaved as liquid‐like systems. The relaxation maxima shifted to shorter relaxation times, and the heights of the maxima decreased with increasing milling time. The relationship between the complex viscosity η* and steady‐shear viscosity η gradually altered from η* > η to η* < η as the milling time increased. The results can be used to determine the processing conditions of milled starch.