挤压膨化工艺参数对夏秋绿茶多酚含量及膨化度的影响

利用双螺杆挤压膨化机对夏秋绿茶进行挤压膨化,研究物料含水量、套筒温度以及螺杆转速对膨化绿茶粉中茶多酚含量以及膨化度的影响,并分析夏秋绿茶膨化前后浸出功能成分及微观结构的变化。结果表明:随物料含水量增加,茶多酚含量先减少后增加;增加套筒温度会增大茶多酚的浸出,当温度过高时会导致茶多酚的损失;随螺杆转速增大,茶粉破损程度加大,促进茶多酚的浸出。套筒温度、螺杆转速对挤出物膨化度的影响较小,物料含水量的影响相对较大。与未加工夏秋绿茶粉相比,加工后的夏秋绿茶粉中茶多酚、粗纤维、可溶性总糖含量降低,茶氨酸含量增高。夏秋绿茶膨化后,其表面结构变得平整光滑,且机械力作用使物料自身化学键断裂。

Effect of extrusion processing parameters on the polyphenol content and expansion ratio of summer and autumn green tea

In this paper, the extruded summer and autumn green tea powder processed with a twin screw extruder, the effects of material moisture, barrel temperature and screw speed on the content of tea polyphenols in green tea powder was studied after extruding. Moreover, the leaching functional components and microstructure changes were also studied. The results showed that the moisture content of the material increased, and the content of tea polyphenols decreased first and then increased; increasing the barrel temperature could increase the leaching of tea polyphenols, while the high temperature would lead to the loss of tea polyphenols; increasing the screw speed could increase the tea powder damageand promote the leaching of tea polyphenols. However, the barrel temperature and screw speed had little effect on the puffing degree of the extrudates, and the influence of material moisture content was relatively large. Compared with unprocessed summer and autumn green tea, the tea polyphenols, crude fiber, total soluble sugar content decreased and theanine content increased in summer and autumn green tea powder processed. After the expansion of summer and autumn green tea, the surface structure was observed to be flat and smooth under a scanning electron microscope, and the mechanical force caused the cleavage of the chemical bond of the material itself.