压榨是生产半硬质和硬质干酪的重要工艺。通过检测干酪的化学成分、质构特性、流变特性,研究了压榨过程中压榨时间、压强等参数对干酪品质特性的影响,并且结合共聚焦激光显微镜等手段分析了压榨工艺与干酪微观结构的关系。结果显示,随着压榨时间增加、压强增大,干酪样品的水分含量下降,脂肪和蛋白含量升高。随着压榨时间的延长、压强增大,用质构仪测得干酪的硬度和咀嚼性增大,弹性减小。流变仪测定结果显示干酪的弹性模量增加,熔化性减弱。干酪微观结构图显示,随着压榨时间的延长,蛋白网络更加致密有序;随着压榨压强的增大,脂肪球大量聚集,蛋白分子重列。研究结果揭示了压榨过程影响干酪品质的相关机理。

Pressing is the last procedure and the least understood step of semi-hard and hard cheese making. The aim of this paper was to assess the effect of the pressing time and pressure on cheese properties. The chemical composition,the texture and the rheological properties of cheeses made with different pressing parameters were investigated.And their microstructure was also studied by confocal laser microscopy. The results showed that as time and pressure were increased,moisture content of cheese samples decreased,while fat and protein content increased significantly.As the time and pressure increased,texture testing showed that the hardness and chewiness of cheese were significantly increased,while the flexibility was significantly decreased. Rheometer testing showed that the elasticity modulus of cheese increased,while the melting of cheese weakened. Cheese microstructure pictures showed that,with the extension of the pressing time,the protein network was more compact and orderly. With the increase of pressing pressure,a large number of fat globules aggregated. The mechanism of the effect of pressing on the cheese properties was also discussed.