Study On The Retrogradation Properties And Influencing Factors Of Glutinous Rice Starch

The food products of glutinous rice have high starch content, which retrograded easilyduring storage. Therefore it is vital to study the retrogradation properties and factorsinfluencing glutinous rice starch for controlling the quality of food and retaining freshness.The main contents of this paper are as follows: The optimization of alkaline separationmethod of glutinous rice starch and its characteristics; Detection and analysis the retrogradationindexs of the glutinous rice starch gel during storage; the effects of gelatinization methods andinhibitor on the retrogradation of glutinous rice starch.（1）The Response Surface Analysis Methodology was used to optimize the alkalinemethod separation of glutinous rice starch and the best optimal separation conditions were:lye concentration0.34%, liquid-material ratio（mL/g）5:1, soaking time4h. The SEM and RVAwere used to study the granule properties and pasting properties of glutinous rice starch.The result shows that, most of the protein was removed from glutinous rice starch granules,the glutinous rice starch has lower pasting temperature but higher setback than the rawmaterial.（2）The TPAand physicochemical detectionwas used to analysis the changing of textureproperties and physicochemical properties during the retrogradation process of glutinous ricestarch gel.The result show that, as the extension of time, the water holding capacity, moisturecontent, enzyme hydrolysbility, resilience and springiness of glutinous rice starch gel weredecreased while the hardness and gumminess were increased. Moisture content and iodineblue value decreased rapidly at the beginning while leveled off later. Though the hardness wasinfluenced by the moisture content, greater influence was contributed by the amylopectinrecrystallization. The key factor on glutinous rice gel hardening was the amylopectinrecrystallization.（3）The regression coefficient of equation reached a significant level, which was builtwith textural indiactors as dependent variables and the physicochemical indiactor as thevariable,so the regression equation is valid; The model was proved to have good predictionresults by validating the regression equation. Both the physicochemical indiactors and texturalindiactors could represent the change of the glutinous rice starch gel to a certain extent duringthe process of retrogradation, Two principal components of the glutinous rice gel weredetermined by the method of principal component analysis and the variance contribution was Z=0.83Z1+0.17Z2.The inflection point of texture characteristic of glutinous rice starch gel is7d and the critical impact factors are gumminess and hardness, which means that hardness andgumminess can be used as the main index of the quality evaluation of glutinous rice gel.（4）The retrogradation properties glutinous rice gel prepared by the conventionalheating, microwave heating and high pressure heating were investigated,compared with theconventional heating, the microwave heating had no significant effect on the retrogradation ofglutinous rice starch. However, high pressure heating could delay the retrogradation.Monostearate and xanthan gum were chosen for themodifier of glutinous rice starch gel andthe bata of β-enzyme were determined, using the response surface analysis (RSA)and theoptimum formula was selected as follows: monostearate0.43%, xanthangum0.53%,β-enzyme0.18%.（5）TPA,DSC, FT-IR were carried out for the study of anti-retrogradation of starch gels.The results showed that the additives delayed the recrystallization of amylopectin, improvingthe hardness and chewiness, extending the period of storage.