Recent Processing Methods for Preparing Starch-based Bioproducts - Food and Industrial Bioproducts and Bioprocessing - page 53

1976a). Latex-like dispersions were similarly obtained by sonicating graft copolymers
obtained by polymerizing isoprene and acrylonitrile onto gelatinized wheat starch and onto
a cationic starch derivatized with a quaternary amine (Gugliemelli et al ., 1979 ). In a series
of later publications, starch graft copolymer latexes were prepared from methyl acrylate,
butyl acrylate, methyl methylate and acrylonitrile, and the use of these latex-like dispersions
as stabilizers to inhibit the water-erosion of soil was examined (Weaver and Fanta, 1987;
Weaver, 1988 , 1989 , 1989 ). Laboratory tests showed that starch graft copolymers prepared
from methyl acrylate and butyl acrylate showed good performance for this area of application.
Ultrasound has been used in the preparation of starch derivatives and also to modify
starch for specific end-use applications. Mongenot and co-workers (2000) investigated the
encapsulation of liquid cheese aroma in different carbohydrate matrices by spray drying,
and used ultrasound to obtain stable emulsions with maltodextrin, which normally has poor
emulsification properties. Spray-dried maltodextrin microcapsules were more effective for
retaining cheese aroma when ultrasound was used for emulsification, as compared to high-
speed homogenization. Huang and co-workers (2007) studied the effect of ultrasound on the
properties and chemical reactivity of corn starch granules. Starch granules were suspended
in water at a concentration of 30% and ultrasonic treatment times varied from 3 to15 min.
Degree of hydrolysis (determined from the percentage of soluble saccharides formed in the
aqueous starch suspensions) varied from 3.1% after three minutes sonication to 18.4% after
15 min. Little additional effect was observed with further treatment times. Although the pore
sizes in sonicated granules increased as the degree of hydrolysis increased from 3.1 to
18.4%, there was little change in the birefringence patterns of the sonicated granules. The
sonicated granules showed the native A-type X-ray diffraction pattern and there was little
change as the degree of hydrolysis increased from 0 to 18.4%. The effect of ultrasonic
treatment on the reactivity of the starch granules with propylene oxide was then determined.
Although an increase in degree of hydrolysis from 0 to 3.1% did not significantly change the
DS and reaction efficiency, a further increase in the degree of hydrolysis up to 15.7%
resulted in a significant increase in DS. When the degree of hydrolysis was greater than
15.7%, decreases in DS and reaction efficiency were observed.
The effect of ultrasound on the preparation of acetate derivatives of yam starch was
investigated by Zhang and co-workers (2008). Comparison of reactions carried out in the
presence and absence of ultrasound showed that the use of ultrasound enabled the
esterification reactions to be carried out with shorter reaction times and decreased amounts
of catalyst.

ižová and co-workers (2008) used ultrasound and microwave irradiation to
shorten the reaction time needed to synthesize water-soluble octenylsuccinates of
carboxymethyl starch using DMSO as a solvent. Kim and co-workers (2008) prepared small
starch particles by hydrolyzing the amorphous regions of waxy rice starch with alpha -
amylase and then treating the enzyme-hydrolyzed starch with ultrasound in ethanol to
fragment the starch granules. Practical applications for small starch particles in areas such
as flavor delivery, fat substitutes, and reinforcing fillers for polymers are currently of
interest. Grinberg and Gedanken (2010) also developed a process degrading starch into
small fragments with ultrasound and then organizing these fragments into microsphere
structures containing encapsulated insulin.
Treatment with ultrasound has also been used to enhance the reactivity of starch with
enzymes. Barton and co-workers (1996) studied the effects of ultrasound on the activities of
alpha-amylase and glucoamylase toward soluble potato starch. With

Č

-amylase, increased
reaction rates were observed with sonication at low concentrations of starch (8 g per liter);
although at starch concentrations of 15-50 g per liter, both sonicated and un-sonicated

α