Interactions Between Inulin And Wheat Starch

Inulin is a kind of linear polysaccharide connected with D-fructose by ?(2?1)bonds.It was approved as the new food resources in 2009 because of its prominent role in the physiological function and quality improvement.This research studied the effects of inulin with different degree of polymerization(DP)and addition amount on wheat starch.Inulin-starch system was used to study the effect of inulin on wheat starch structure.The results contributed to a better understanding of processing theory and technology of inulin in wheat flour dough and provided a scientific basis for depth of application of inulin in food industry.The main conclusions are as follows.(1)The addition of three kinds of inulin could increase the difficulty of gelatinization of wheat starch and increase the gelatinization temperature.The addition of inulin can reduce the BD value of the starch and then enhance the heat stability of the starch granules.The starch had the minimum enthalpy value when the three kinds inulin were addedd to 7.5%,and the enthalpy of the starch was reduced by 45.1%,43.3% and 31.3%,respectively.When the addition amount of the three kinds of inulin was 7.5%,the aging rate of starch reached the minimum value,which was 16.5%,17.4% and 20.7% respectively,compared with pure starch aging rate decreased by 44.3%,41.2% and 30.1%,respectively.Inulin could inhibit the recrystallizatic of amylose and promote the recrystallization of amylopectin during storage.When the concentration of three inulin was less than 10%,inulin could play a role in anti-retrogradation in the long term storage process.when the concentration of three inulin was more than 10%,the effect was opposite,the anti-retrogradation effect of inulin on starch gradually decreases,and even promotes retrogradation.In general,the effect of FS and FI on the gelatinization,retrogradation and crystallization of starch were obvious.(2)The addition of three inulin could significantly reduce the stickiness and adhesiveness of the gel,the hardness,cohesion and chewiness of the gel were increase first and then decrease.In general,the addition of inulin to the appropriate concentration can improve the processing properties of the starch gel.In static scans,the addition of inulin does not alter the pseudoplastic fluid properties of the starch gel.FS increased the mobility of the gel;the addition of FI and FXL had no significant effect on the mobility of the gel.Dynamic rheological tests showed that the starch gel containing FS and FXL were not easily deformed under external forces.The addition of FI causeed the stability of the gel was reduced,and the starch gel to be deformed easily by external forces.When the addition of FXL was less than 10%,the curing temperature of the starch gel could be significantly increased.When the addition of three kinds of inulin were more than 10%,the curing temperature of the starch gel was significantly lower than that of the pure starch gel.FXL and low concentration of FS could improve the stability of the starch gel during storage in 5°C,and FI could reduce the stability of the starch gel during storage.In combination,the appropriate amount of FS and FXL had the better effect to improve the texture characteristics and stability of gel in dynamic process.(3)There was one single transition step on the DSC curve of the inulin-starch blend,and the glass transition temperature of the blend was between the pure substance of the inulin and starch,indicating that the three kinds of inulin and wheat starch blends were compatible.The leakage of amylose content of the mixture was reduced after adding the inulin,which indicated that the inulin molecules mainly interacted with amylose during starch.This also showed that inulin mainly affects the retrogradation process of starch by affecting the recrystallization of amylose molecules.The hardness of starch gel was mainly affected by urea solution,indicating that the interaction between inulin and starch molecules mainly through hydrogen bonding.With the increase in inulin concentration,the interaction between molecules gradually increased.The infrared spectra does not produce a new absorption peak,indicating that there was no new group between inulin and starch.