Effect Of Wheat Fiber On The Gelatinization And Retrogradation Of Wheat Starch

Starch is a widely distributed substance in nature and possesses application in the food industry.However,starch after gelatinization is easy to retrogradation,affecting the quality and practical value of starchy foods.The addition of wheat fiber can increase the content of dietary fiber in starch-based foods and improve the physical and chemical properties of wheat starch gel.In this study,wheat fiber was used as the object to study the effect of wheat fiber on the gelatinization and retrogradation properties of wheat starch.The wheat fiber was pretreated by steam explosion.The effects of wheat fiber on wheat starch properties before and after treatment were analyzed.The application of the medium and the development of dietary fiber fortified food provide theoretical basis.Wheat starch was used as raw material to study the effects of wheat fiber on the gelatinized viscosity properties,thermal properties,rheological properties,crystalline and microstructure of wheat starch.The results showed that the addition of wheat fiber significantly reduced the regenerative value,disintegration value and gelatinization value of wheat starch gel,and it was negatively correlated with the addition amount.Wheat starch is a pseudoplastic fluid.When wheat fiber is added,the shear stability is enhanced and it can significantly affect the viscosity of wheat starch.At the same time,it can obviously reduce the aging value and relative crystallinity of the starch gel to form a more continuous and dense gel structure.When the addition amount of wheat fiber reached 20%,the retrogradation value decreased from 1215.33mPa·s-1 of original starch to 519.33mPa·s-1.After storage for 28 days,the aging value decreased from 5.83J/g of original starch to 3.10J/g,the relative crystallinity decreased from 22.17%of the original starch to 12.62%.It indicated that wheat fiber could inhibit the short-term aging and long-term aging of wheat starch gel and significantly enhance the refrigeration stability of wheat starch gel.Therefore,wheat fiber can be used as a novel starch aging inhibitor in starch-based foods.Wheat fiber can adsorb the water in the starch gel system in a large amount,hinder the repolymerization of starch molecules,inhibit the formation of large ice crystals during the freezing and thawing process of wheat starch gel,and significantly reduce the aging enthalpy and relative crystallinity.Gel.It indicated that wheat fiber can significantly enhance the freeze-thaw stability of wheat starch gel and it is positively correlated with the amount of addition.Therefore,wheat fiber can be used as a new freeze-thaw stabilizer in quick-frozen foods,prolonging the shelf life of food and improving food quality.After steam explosion pretreatment,the average particle size of wheat fiber is significantly reduced,the specific surface area is significantly increased,and more water binding sites are exposed,thereby enhancing the water absorption and water holding capacity of wheat fiber.When the steam explosion pretreatment pressure is 1.6 Mpa,the particle size is the smallest.There is no new absorption peak in the infrared spectrum of the modified wheat fiber,that is,no new chemical structure and functional groups are formed,and the stability of the colloidal suspension after modification is remarkably improved.The results show that steam explosion pretreatment of wheat fiber is a very effective physical modification method.The effects of modified wheat fiber obtained by steam explosion pretreatment at different pressures(1.4Mpa,1.6 Mpa and 1.8 Mpa)on the gelatinization and aging characteristics of wheat starch were compared by RVA,DSC,XRD and SEM.The results showed that the addition of wheat fiber after steam explosion treatment significantly reduced the disintegration value and retrogradation value of wheat starch,enhanced the stability of wheat starch paste,inhibited the short-term aging of wheat starch,and the gelatinization viscosity and gelatinization value.Both of them decreased.When the steam explosion pretreatment pressure reached 1.6 Mpa,the decrease was the largest,and the delay effect on wheat starch gelatinization was the most significant.As the treatment pressure increases,the aging enthalpy and relative crystallinity of wheat starch decrease first and then increase;a more dense gel is formed.Therefore,the modified wheat fiber can inhibit the aging of wheat starch,and the suppression effect is best when the steam explosion pretreatment pressure is 1.6 Mpa.