挤压处理的预糊化米粉添加量对大米粉理化特性的影响

Effect of the additive amount of extruded pregelatinized rice flour on the physicochemical properties of rice flour

为了探讨挤压制备的预糊化大米粉不同添加量(0%、2.5%、5.0%、7.5%、10.0%、12.5%)对混合米粉和米糊的品质影响,对混合粉的水合特性、冻融稳定性、糊化特性、热特性、流变特性及米糊的静态流变、动态流变特性进行测定。研究表明:添加预糊化大米粉后,米粉的吸水指数提高了2.10%~14.34%,且米粉凝胶的回生值、峰值和谷值黏度分别降低了3.99%~19.29%、4.94%~25.20%和3.05%~16.59%;差示扫描量热结果表明添加预糊化大米粉后,峰值温度升高,糊化焓降低了7.62%~17.05%;添加预糊化大米粉后混合米粉凝胶的储能模量和损耗模量均减小,米糊的稠度系数K增加了0.69~7.95倍,米糊的触变性增强;米糊的储能模量和损耗模量均减小,但损耗角正切值增加。在大米粉中添加预糊化大米粉,水合特性与冻融稳定性都得到一定的提高,回生值以及热焓值减小,米制品的老化以及蒸煮或烘焙时间降低。

In this study,extruded pregelatinized rice flour was added to rice flour with mass fractions of 0%,2.5%,5.0%,7.5%,10.0%,and 12.5%,then,the changes in the quality of the mixed rice flour and rice paste were determined,including water hydration,freeze-thaw stability,pasting,thermodynamics,rheological properties,static and dynamic rheological properties.The results showed that the addition of pregelatinized rice flour increased the water absorption index of rice flour by 2.10%,and the regain,peak and valley viscosities of rice flour gels were reduced by 3.99%,4.94%and 3.05%,respectively.The peak value,valley value and final viscosity of the mixed system decreased significantly with the increase of pregelatinized rice flour addition,and the attenuation value and regeneration value of the rice flour gel decreased significantly,but the effect on the pasting temperature was small.After the addition of pregelatinized rice flour,the water precipitation rate of the mixed rice flour decreased significantly from 60.43%to 56.44%,hence there was a negative correlation between the water precipitation rate and the amount of pregelatinized rice flour added.The DSC results showed that the addition of pregelatinized rice flour increased the peak temperature and decreased the enthalpy of pasting by 7.62%,hence,the thermal stability of rice flour was reduced by the addition of pregelatinized rice.The energy storage and loss modulus of the rice flour gels decreased,the consistency factor K of rice paste increased by a factor of 0.69,and the thixotropy of the rice paste increased with the addition of pregelatinized rice flour.The energy storage modulus and loss modulus of the rice paste decreased,but the loss angle tangent increased.In summary,the addition of pregelatinized rice flour to rice flour resulted in a certain improvement in hydration characteristics and freeze-thaw stability,and a reduction in the regrowth value as well as enthalpy,which can reduce the ageing and cooking or baking time of rice products.