Effect of ultrasound assisted acid hydrolysis in combination with heat moisture treatment on digestibility and physicochemical properties of corn starch

In this research the production of resistant starch (RS) from normal corn starch using heat moisture treatment (HMT) in combination with ultrasound assisted acid hydrolysis (HMT-USAH) or conventional acid hydrolysis (HMT-AH) was studied. USAH was carried out as follow: starch sample was suspended in 10% citric acid for 45 min at 45 ̊C under sonication (400 W, 20 kHz). AH starch was prepared similarly while no sonication was applied. Subsequently, USAH, AH and native starch were heat moisture treated at 120 ̊C at 30% moisture content for 8 hours. Resistant starch content of starch samples were increased from 8.3% in control sample to 13.2, 21.4 and 36.8 for HMT-native, HMT-AH and HMT-USAH samples. HMT-acid hydrolysis methods reduced the swelling power and gelatinization enthalpy of starch samples while, solubility, oil absorption, emulsion stability and gelatinization temperatures were enhanced. X-ray diffraction results revealed that HMT-USAH didn’t change the diffraction pattern of native starch.