Isolation of native starches
Waxy corn starches were isolated using the method of
Jiranuntakul, Puttanlek, Rungsardthong, Puncha-arnon, and
Uttapap (2011) with slight modifications. Corn kernels, 400 g for
each sample, were steeped in water containing 0.16% sodium
hydrogen sulfite at 50 ◦C for 24 h to inactivate the enzymes. The
steeped water was drained off, and the grains were ground in
a blender. The ground slurry was screened through a 106 m
sieve. The cloudy supernatant was removed, and the sediment
was re-slurried in 0.2% sodium hydroxide solution. Then the
supernatant was discarded, and the starch cake was re-suspended
in water. The starch slurry was then passed through a 63 m sieve.
The starch was given repeated washings with water until the pH
of the starch slurry reached 7. The starch cake was then dried in an
oven at 40 ◦C for 24 h.