Comparison Of Properties Of Pregelatinized Rice Starch Prepared Using Different Water Content And Its Application In Rice-cakes

Pregelatinized starch is a kind of modified starch obtained by high temperature heating.The properties of different pregelatinized starches with the same raw materials during preparation are different.It has not been reported whether this difference is related to the water content in preparation of pregelatinized starch.In this paper,the structural characteristics,physicochemical properties,retrogradation characteristics,and application in rice-cakes of pregelatinized starch prepared using different starch concentrations,namely different water content,were compared.This provided a reference for developing different properties of pregelatinized starches for different applications.The main research results are as follows:Pregelatinized rice starch was prepared at different starch concentrations(5%,10%,20%,30%).The structural characteristics of different samples were analyzed based on particle morphology,particle size,crystal structure,short-range structure and distribution of amylose.The results showed that the A-type crystal structure of rice starch almost disappeared after gelatinization.No new chemical groups were formed during the whole process.With the increase of water content in the preparation process,the pores and cracks of the pregelatinized rice starch particles increased,and the sample prepared at 30%starch concentration had the largest particle size.The short-range order of starch structure decreased gradually.More amylose was released into the water,and the amylose content in the precipitate gradually decreased.The physicochemical properties of pregelatinized rice starch prepared using different water content were different in cold water and hot water.The results showed that with the increase of water content during preparation,the solubility,swelling power,transparency,cold paste viscosity and freeze-thaw stability of pregelatinized rice starch in cold water increased gradually,while the sedimentation decreased,and the time for solution to reach stability was prolonged.The final sedimentation volume increased first and then decreased,and reached the maximum when the starch concentration was 10%.The solubility,swelling power,transparency and final sedimentation volume of pregelatinized rice starch in hot water increased firstly and then decreased with the increase of water content during preparation,and reached the maximum when the starch concentration was 10%.There was no significant difference in freeze-thaw stability between different pregelatinized rice starches(p>0.05).The experiment of gelatinization characteristics showed that the viscosity of the sample increased with the increase of water content during preparation,while the breakdown decreased.The retrogradation rate of pregelatinized rice starch prepared using different water content was different and related to the water temperature during reprocessing.Thermal properties,recrystallization,short-range ordered structure,and texture were used as indexes to investigate the retrogradation characteristics of pregelatinized rice starch in cold and hot water.The results showed that with the increase of water content in the preparation process,the retrogradation enthalpy,retrogradation ratio,relative crystallinity,R_1047/1022 value and hardness of pregelatinized rice starch decreased.It indicated that the retrogradation rate of pregelatinized rice starch prepared under more water was slower.After the pregelatinized rice starch was cooled in hot water,the samples prepared under high water content(starch concentration?10%)were prone to retrogradation.Compared with the samples prepared under low water content,the retrogradation enthalpy,relative crystallinity,R_1047/1022 value and hardness were higher.The quality of rice-cakes could be improved obviously by adding pregelatinized rice starch prepared under high water content.The effects of pregelatinized rice starch prepared using different water content on the quality of rice-cakes were studied with specific volume,chroma,sensory evaluation,texture and storage quality as indexes.The results showed that the higher the water content in the process of preparing pregelatinized rice starch,the larger the specific volume of rice-cakes,and the smaller the luminosity.The pregelatinized starch prepared under high water content could significantly reduce the hardness,chewiness and adhesiveness of the rice-cakes,and increase the springiness,sensory evaluation score and storage quality of the rice-cakes.