碎绿茶制备速溶茶双螺杆挤压预处理工艺优化

Optimization of twin-screw extrusion pretreatment process for preparing instant tea from broken green tea

本文以绿茶加工过程中的副产物碎绿茶为原料,经双螺杆挤压预处理后,采用单罐热浸提法制备速溶绿茶。论文重点在考察双螺杆挤压操作参数(机筒温度、螺杆转速、加水量、茶粉喂料量)分别对速溶绿茶品质指标(速溶茶的得率、茶多酚得率、茶多酚含量)影响的基础上,以速溶绿茶的茶多酚得率为主要考察指标,采用4因素3水平的正交试验优化制备速溶绿茶挤压预处理工艺参数。研究结果表明:双螺杆挤压操作参数(机筒温度、螺杆转速、水分添加量、茶粉喂料量)对速溶绿茶品质指标(速溶茶得率、茶多酚得率、茶多酚含量)产生了显著影响;优化的最佳双螺杆挤压操作参数为水分添加量50%、螺杆转速210 r/min、机筒温度95℃、茶粉喂料量11 kg/h,在该条件下生产的速溶绿茶茶多酚得率4.81%,相比未经双螺杆挤压预处理制备的速溶绿茶对照样品得率(2.88%),茶多酚得率提高了1.67倍。研究结果表明采用双螺杆挤压预处理技术制备速溶茶在实际应用中具有较好的发展潜力。

In this study,instant green tea was prepared by the single pot hot-extraction using broken green tea pretreated by twin-screw extrusion technology.First,the effects of different twin-screw extrusion parameters(barrel temperature,screw speed,moisture content,feed amount of tea powder)on the quality of instant green tea(yield of instant tea,yield of tea polyphenols,content of tea polyphenols)were investigated.Then,with the yield of tea polyphenols as the main index,the parameters for extrusion pretreatment of instant green tea were optimized by orthogonal test with 4 factors and 3 levels.The results showed the operating parameters of twin-screw extrusion(barrel temperature,screw speed,water content,feed amount of tea powder)had significant effects on the quality indexes of instant green tea(yield of instant tea,yield of tea polyphenols,content of tea polyphenols).The optimum parameters of twin-screw extrusion were as follows:moisture content of 50%,screw speed of 210 r/min,barrel temperature at 95℃,tea powder feeding rate at 11 kg/h.Under these conditions,the yield of instant green tea polyphenols was 4.81%,which was 1.67-fold higher than that of traditional method(2.88%).The results suggest that the preparation of instant tea by twin-screw extrusion pretreatment has a good potential in practical application.