Structural changes induced by high speed jet on invitro digestibility and hydroxypropylation of rice starch

Influences of high speed jet (HSJ) at different pressures (0, 80, 160, 250MPa) on digestibility and hydroxypropylation of rice starch were evaluated. HSJ treatment increased the content of rapidly digestible starch and slowly digestible starch and decreased the content of resistant starch with increasing of the treatment pressure in native starch. The degree and the reaction efficiency of hydroxypropylation of rice starch increased with an increase in treatment pressure. Scanning electron microscopy and X-ray diffraction analysis showed that both the crystalline structure and the overall granular structure were partially destroyed. Meanwhile, HSJ treatment led to degradation of starch molecules. The results suggested that the changes of starch structure resulted in decreasing gelatinisation enthalpy of rice starch and might be response for the changes of reactivity and its digestibility to some extent.