The particle size of corn flour powder containing Zein protein and corn starch was reduced by hydrolysis under alkali condition
at the elevated temperature and followed by a high shearing force to break up the starch gel. Both amide bond in protein
(polyamino acids) and ether bond in starch can be hydrolyzed under acid or base condition to break up the polymers
into smaller segments. Fig. 1 shows the number and volume average size of corn flour particles. The hydrolyzed CF has a
number-averaged size of 500 nm compared to a number-averaged size of 10 lm for the CF without hydrolysis. The
volume-averaged size of hydrolyzed CF is 2.8 lm because the larger particles scatter more light and are weighted more
in the light scattering method. The disparity between the number and volume averaged size of hydrolyzed CF also indicates
that the dispersion is inhomogeneous.
To analyze the amount of small particle size in the hydrolyzed CF dispersion, the dispersion was filtered through a 0.7 lm
filter. After the filtration, 91% of hydrolyzed CF passed through the 0.7 lmfilter, and their number and volume averaged sizes
are 300 and 370 nm, respectively. This indicates that the current procedure significantly reduced 90% of CF to an average
size of 300 nm, a size reduction of 33 times. The particle size of NR latex is also included for comparison in Fig. 1. They are
600 and 840 nm for the number and volume average, respectively. About 91% of the hydrolyzed CF has a particle size smaller
than NR particles. The significant difference in the particle size between the CF and hydrolyzed CF is also reflected in their
specific surface areas (cm2/cm3), which changed from 4.1 103 to 1.7 105. The particle size change is also reflected in FTIR
of the composites shown in Fig. 2. The number of hydroxyl groups of HCF increased significantly compared to CF because of