High amylose corn starch (70%) was dried in a
walk-in dryer at 50 ◦C for 48 h. To begin the acetylation
process, 110 kg acetic anhydride were placed in
a steam-jacketed reactor with a rotating self-wiping
paddle. Then, 45.5 kg of 70 % amylose starch were
added into the reactor with 5 min of continuous mixing.
Finally, 5 kg of 50% NaOH solution were added
while mixing. The temperature of the reactor jacket
was maintained at 123 ◦C. After 3 h, the reaction was
stopped by quickly adding 200 L of cold water to the
reactor. The pH value of the mixture was adjusted to
5.0 by washing with water before drying the mixture
at 50 ◦C in a walk-in dryer. After the moisture was
constant (4%), starch was ground in a Standard model
No. 3Wiley mill (Arthur H. Thomas Co., Philadelphia,
PA) and then passed through a 5mm opening sieve