Effect Of Inulin On Physicochemical Properties Of Rice Starch And The Quality Of Rice-cakes

Rice starch and inulin are the research objects in this study.The effects of inulin on the physicochemical properties such as digestion,viscosity,rheological property,gel texture,crystallinity,leakage amount of amylose and freeze-thaw stability and the ability of retrogradation resistance were studied.In addition,the effects of inulin on cakes qualities and texture of inulin rice-cakes were also studied.Results are as follows:The Englyst method was used to study the influence of inulin on the digestibility of rice starch.When inulin content up to 15%,the degree of hydrolysis reduced nearly 7%.The invitro digestion rate k of blend system also decreased,which suggested that inulin can inhibit the hydrolysis rate and degree of hydrolysis of the rice starch in some degree.The content of resistant starch in the mixing system increased from 27.7% to nearly 33%,which indicated that inulin can improve the nutritional quality of rice starch.The rheological characteristics showed that the blend system tends to be Newtonian fluid,which is good for the shape maintenance of starch-based food;Area of thixotropic loop reduced from 1077.48 Pa·s-1 to 104.07 Pa·s-1,which suggested that the energy needed for mixing system recovery after shearing was declined.The results of freeze-thaw stability indicated that the inulin can reduce the syneresis of the blend system,and improve its freeze-thaw stability.Gel characteristics results showed that the gel strength decreased from 25 g to 15 g,which suggested that the system tended to form a more soft gel.By leach amylose content determination,X-ray diffraction and rapid viscosity analysis,the mechanism of inulin inhibiting rice starch retrogradation was studied.Results showed that with the increase of proportion of inulin,the leach of amylose content decreased from 19% to 10.5%,re-crystallinity decreased from 8.95% to 5.13%,retrogradation decreased from 1258 cp to 1088 cp.Single factor and orthogonal test were used to determine the optimum addition of inulin for the rice-cakes.The optimal parameters are as follows: water content 57.5%,ratio of glutinous rice powder and japonica rice powder 3:2(g/g),inulin addition 3%.The instrumental analysis results were in good correlation with the sensory evaluation of inulin rice-cakes.