Effect of ethanol concentration on the physicochemical properties of waxy corn starch treated by hydrochloric acid

Waxy corn starch was treated in 50, 70 or 90% of ethanol solutions containing 0.36 or 1.39% HCl at 65 °C for 1 h. The recovery yields of treated starch were higher than 96%. The average granule size, maximum wavelength of the spectrum of iodine coloration (λmax), pasting viscosity, gelatinization onset temperature (To), average molecular weight and average chain length of starch decreased after treated, while no obvious change on X-ray diffraction pattern and increase in solubility of treated starch was also found. The changes on pasting viscosity, To, average molecular weight and solubility of treated starch increased with increasing ethanol and acid concentrations. It was found that the solubility of acid–ethanol treated waxy starch was a function of T/To (T was the temperature used for solubility measurement). At T/To below 1.2, the solubility of starch linearly correlated with T/To value (r2=0.984).