Preparation and properties of granular resistant starch

In order to enhance resistant starch (RS) content, and obtain optimal preparation conditions, high-amylose (~70%) corn starch (Hylon VII) were modified by heat-moisture treatment (HMT), enzymatic treatment, and enzymatic treatment combined with HMT. The resulted highest RS content of three modification methods was 51.5%, 42.5% and 55.1%, respectively. Enzymatic treatment combined with HMT could increase resistant starch content. The results showed that after three modification methods, the products remained birefringent and granular appearance, and therefore they were granular resistant starch (RS2). Compared to native starch, appropriate HMT and enzymatic treatment could obviously increase amylose content. X-ray diffraction indicated that HMT and enzymatic treatment did not change the crystalline type and remained “B” type diffraction pattern. The differential scanning calorimeter pattern showed that the temperatures of the onset, peak, conclusion and enthalpy of gelatinization were increased. HMT and enzymatic treatment could prepare granular resistant starch with thermal stability.