差异化蛋白脱除对早籼米粉性质的影响

Effects of differential protein removal on the properties of early indica rice flour

[目的]探究差异化脱蛋白对米粉理化功能性质的影响机制。[方法]采用酶法、碱法对米粉进行差异化蛋白脱除,并对脱蛋白米粉的破损淀粉含量、粒径分布、颗粒表观形态、溶解度、膨润力、糊化特性及质构特性进行分析。[结果]蛋白凝胶电泳(SDS-PAGE)和激光共聚焦(CLSM)结果表明,碱法是等比例脱除各蛋白亚基,而酶法对淀粉颗粒表面蛋白脱除的均一性更好;原粉粒径分布的主峰大约在70μm处,而脱蛋白米粉的主峰则向左偏移至6μm处;随着蛋白含量的降低,脱蛋白米粉的破损淀粉含量呈下降趋势,而弹性、硬度显著升高,其中酶法3%米粉的粒径分布最为均一,D90最小(23.58μm),破损淀粉含量也由原粉的3.32%降低至1.48%,而弹性和硬度相比原粉分别提高了54.55%,52.60%;与原粉相比,脱蛋白米粉具有较低的峰值黏度、崩解值和最终黏度,其中酶法3%米粉的崩解值和回生值均最小,说明其热糊稳定性最好,且不易回生。[结论]碱法和酶法均能有效脱除蛋白,提升早籼米粉的粉质特性,相比之下酶法处理条件更加温和,蛋白和粒径分布更加均一,抑制回生效果更明显。

[Objective]To investigate the mechanism of the effect of deproteinisation on the physicochemical and functional properties of rice flour.[Methods]Enzymatic and alkaline methods were used to remove protein from early rice flour,and the damaged starch content,size distribution,morphology,solubility,swelling power,pasting characteristics and textural characteristics of the deproteinized rice flour were analyzed.[Results]Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and confocal laser scanning microscope(CLSM)showed that the alkaline method equally removed the protein subunit where as the enzymatic method showed a better homogeneity of protein removal from the surface of starch.The size distribution of the control showed a majorpeak at ca.70μm and it shifted to 6μmafter protein removal.With the reduction of the protein content,and the damaged starch content of the deproteinized rice flour decreased while its elasticity and hardness increased.The deproteinized rice flour with 3.0%of protein(RFA@3.0),which was treated by alkaline method,showed a most uniform particle distribution,and a minimum D90 of 23.58μm was observed.When compared to the control,its damaged starch content decreased from 3.32%to 1.48%while the elasticity and hardness increased by 54.55%,52.60%,respectively.The deproteinized rice flour had lower peak viscosity,breakdown viscosity and final viscosity than the control,and the RFA@3.0 had minimum breakdown and setback viscosities,which indicated that it exhibited best paste stability and was difficult to retrograde.[Conclusion]The protein removal by alkaline and enzymatic methods can improve the properties of early indica rice flour.The enzymatic method has mild reaction conditions and the result and products has better protein and size distribution and are more difficult to retrograde than the rice flour that treated by alkaline method.