苜蓿冰结构蛋白的提取及对冷冻面团的影响

Extraction of Alfalfa Ice Structuring Proteins and Their Effect on Frozen Dough

以"肇东"紫花苜蓿干草为原料。利用磷酸盐缓冲溶液法提取苜蓿蛋白,通过单因素和响应曲面试验,得到提取苜蓿蛋白的最佳工艺条件为料液比1∶20、磷酸盐缓冲溶液浓度63 mmol/L、p H 7.7、草粉粉碎粒度80目、搅拌时间2 h。在此条件下苜蓿蛋白的提取率为37.77%。经硫酸铵沉淀,透析脱盐,冷冻干燥后复溶,对其溶液进行冰晶形态观察,可以看出苜蓿蛋白的冰晶体积小、数量多、形态多样,说明其抑制冰晶生长及对冰晶的形态修饰效果显著,具有很好的抗冻活性,为冰结构蛋白。将其应用于冷冻面团后,冷冻面团的硬度明显降低,弹性、回复性和内聚性稍增强,咀嚼性有所降低,质地细腻柔软。

In the present study, proteins were extracted from the young stems with leaves of Zhaodong alfalfa with phosphate buffer solution. Furthermore, the optimal extraction conditions for alfalfa proteins were determined by singlefactor experiment and response surface methodology. The results revealed that when the extraction was carried out by 2 h stirring of the 80-mesh raw material powder suspended in 63 mmol/L phosphate buffer solution at p H 7.7 with a solid/liquid ratio of 1:20, the yield of alfalfa proteins was 37.77%. The observed ice crystal morphology suggested that the ice crystals of the purified alfalfa proteins were small in size, increased in number and varied morphologically, indicating that the alfalfa proteins are able to significantly inhibit the growth and modify the conformations of ice crystals. These results demonstrate that the alfalfa proteins, which possess excellent antifreeze activity, are ice structuring proteins. In addition, we characterized the functional role of these alfalfa proteins in practical application by application in frozen dough. The results of texture properties demonstrated that the frozen dough mix had a soft and delicate texture, and increased elasticity, resilience and cohesion, but reduced chewiness.