米粉中蛋白组分对陈化后淀粉颗粒间解聚的影响

Effect of protein components in rice flour on disaggregation of starch granules after aging

为揭示米粉中脂肪和各蛋白对其陈化后糊化过程中淀粉颗粒间解聚集的影响,以富含蛋白的米粒外层为研究对象,比较储前各蛋白逐一脱除并经陈化后,糊化粒度分布和显微形态的变化。结果表明,随着米粉中脂肪和清蛋白的脱除,所得样品陈化前后的粒度分布差异趋于消失。清蛋白的存在明显抑制了淀粉颗粒间的解聚,而脂肪的存在则对淀粉颗粒间的解聚具有一定的促进作用,陈化后这种影响愈加明显。陈化中清蛋白和脂肪对抑制淀粉颗粒间解聚变化的陈化贡献率分别为118%和-18%,而球蛋白、谷蛋白和醇溶蛋白对淀粉颗粒间解聚的影响不大,光学显微观察较好地支持了粒度分析结果。而且,米粉中清蛋白的存在使陈化后峰值黏度和衰减值显著减小,成糊温度显著增大,表明陈化中清蛋白引起的淀粉颗粒间解聚变化明显改变了糊化特性。因此,米粉陈化中清蛋白的变化使淀粉颗粒间难于解聚,是米粉陈化后糊化特性变化的主要原因,这对于揭示稻米陈化机制具有重要意义。

To reveal the effects of lipid and proteins in rice flour on the disaggregation of starch granules after aging and heating,taken the outer layer rich in proteins of rice grains as material,the particle size distribution and microscopic morphology changes of residues after protein removal one by one and aging were compared.The results showed that the difference in particle size distribution of the obtained residues disappeared between before and after aging with the removal of lipid and albumin in rice flour.The albumin inhibited the disaggregation of starch granules,while the presence of lipid promoted the disaggregation of starch granules,and this effect became more obvious after aging.In the aging process,albumin and lipid contributed 118%and-18%to the difficulty of disaggregation of starch granules due to aging respectively,while globulin,glutelin and prolamin had little effect on it.The results of particle size analysis were supported by light microscope observation.Moreover,the presence of albumin in rice flour significantly reduced peak viscosity and breakdown and increased pasting temperature after aging,which indicating that the disaggregation difficulty of starch granules caused by albumin aging significantly changed pasting properties.Therefore,that the changes of albumin in rice flour during aging make starch granule difficult to disaggregate is the main reason for the changes in pasting properties of rice flour after aging,which is of great significance to reveal the aging mechanism of rice flour.