Effect of acid hydrolysis in the presence of anhydrous alcohols on the structure, thermal and pasting properties of normal, waxy and high-amylose maize starches

P>Maize starches with different amylose contents (0%, 23% and 55%) were treated in anhydrous methanol, ethanol, 2-propanol, 1-butanol with 0.36% HCl at 25 degrees C for 5 days. Results showed that the extent of change in physicochemical properties increased from methanol to butanol. Treated waxy maize starch showed higher than 65% solubility at above 75 degrees C. The diffraction peak at 2 theta = 5.3 degrees of amylomaize V starch disappeared after treatment in ethanol, 2-propanol and 1-butanol. Acid-alcohol treatment decreased the gelatinisation temperature of normal (from 64.5 to 61.9 degrees C) and waxy maize (from 68.1 to 61.1 degrees C) starches, while it increased that of amylomaize V (from 68.7 to 72.3 degrees C) starch. The extent of the decrease in the pasting viscosity followed the following order: amylomaize V < normal maize < waxy maize. This study indicated that acid-alcohol treatment degraded preferentially the amorphous regions and the different changes depended on the crystal structure and amylose content of starch.