Prediction of the Dispersity
of Ultrasonically Treated Starch Hydrogels
N. V. Losev and I. M. Lipatova
Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, Russia
Received July 30, 2008
Abstract—Expressions for calculating the expected particle size of the colloid phase and the gain in the
content of the water-soluble fraction in starch hydrogels upon their ultrasonic treatment were obtained.
AND POLYMERIC MATERIALS
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 6, pp. 1070–1073. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © N.V. Losev, I.M. Lipatova, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 6, pp. 1013–1016.
Gelatinous starch materials are widely used in
various branches of industry (textile, food, paper,
building). To make starch hydrogels technologically
applicable, they are subjected to thermal or
thermochemical treatment to break down their primary
structure formed by swollen starch grains. Ultrasonic
treatment of gelatinized starch allows the time and
power consumption for the breakdown of starch grains
to be considerably reduced, and the level of the
hydrogel dispersity attained in the process cannot be
reached by traditional thermal treatment. Strong
acoustic fields in liquid media can be generated both
by common ultrasonic apparatus and by hydroacoustic
devices, in particular, by rotary-pulse apparatus [1, 2].
Wide use of technologies involving ultrasonic or
hydroacoustic treatment of gelatinized starch is
restricted by the insufficiency of the theoretical basis
and lack of reference experimental data for calculation
and construction of apparatus ensuring the required
level of dispersity of starch hydrogels at minimal
The goal of this study was to obtain mathematical
expressions for calculating the expected size of colloid
particles in ultrasonically treated starch hydrogels from
the amount of the acoustic energy absorbed.
Experiments were performed with corn starch
[GOST (State Standard) 7697–82]. Starch hydrogels
for the subsequent ultrasonic treatment were prepared
by cooking starch suspension on a water bath at 90°C
for 15 min.
Starch hydrogels of the concentration in the range
1–8 wt % were subjected to ultrasonic treatment in a
UZDN-2T disintegrator at f = 22 kHz. The exposure
time was from 5 to 60 s. The volumetric density of the
acoustic energy determined calorimetrically was 1.34
The content of the water-soluble fraction of starch
(A, %) was determined by hot extraction, and the
composition of extracts, spectrophotometrically using
complexation with iodine .
The size of colloid particles in starch hydrogels was
determined by turbidimetry from the plot of the
logarithm of the optical density on the logarithm of the
wavelength, as described in . The refractive indices
of the solutions, required for the calculation, were
measured with an IRF-22 refractometer. The optical
densities of the solutions were measured with a
The initial starch hydrogels are dispersions in
which swollen starch grains are distributed in a
solution of the water-soluble fraction. As reported
previously , ultrasonic treatment of starch hydrogels
leads already in the first seconds to a decrease in their
viscosity and optical density and to an increase in the
soluble fraction content. Microscopic studies showed
that this is due to breakdown of starch grains.
In ultrasonic disintegration of particles only a minor
fraction of the acoustic energy imparted to the material