茶叶加工过程中的物理特性变化规律

为了探讨茶叶加工过程中物理参数的变化规律,以春季茶叶为试验材料,分别采用103°恒重法、量筒法、仪器法、注入法和斜面法,研究探讨鲜叶、萎凋叶、杀青叶、揉捻叶、作形茶及成品茶的含水率、容重、孔隙率和休止角,以及茶叶与不同茶机材料静摩擦角的变化规律。研究结果表明,绿茶在加工过程中含水率从73.7%一直下降到4.2%,作形过程中含水率下降最显著,揉捻过程中含水率下降最少;绿茶加工过程中成品茶容重最大,鲜叶容重最小,各加工阶段茶叶的容重变化范围为74.5～210.3kg/m3;鲜叶的孔隙率最大,揉捻叶的孔隙率最小,茶叶在制品的孔隙率在0.696～0.732之间变化;在整个茶叶加工过程中,休止角都在50°～60°之间变化;茶叶在铝板上的静摩擦角最大,浸胶帆布带上的次之,而在铜板、镀锌钢、不锈钢和普通钢板上则相差不大,在所有茶机材料上,作形之后茶叶的静摩擦角最小。

The Changes of Physical Parameters in Tea Processing

To investigate the physical variable parameters of spring green tea in tea processing,103°constant weight method,measuring cylinder method,apparatus method,injection method and inclined plate method are implemented to study the bulk density,porosity,angle of repose and static friction angle respectively.The results show that the moisture content of tea dropped from 73.7% to 4.2% in processing,the moisture content declined fastest in the tea form processing,while in the tea rolling processing the moisture content of tea reduced little;the bulk density of the processed tea is largest while the bulk density is smallest for fresh tea leaves,and the variation range of bulk density is 74.5~210.3kg/m3;the porosity of fresh tea leaves is largest while for the rolled tea leaves the porosity is smallest,and the variation range of porosity is 0.696~0.732;the repose angle during the whole process course vary between 50°and 60°;the static friction angle is largest against aluminum,which is smaller for the adhesive tape and show little difference against copper plate,steel plated by aluminum,stainless steel and ordinary steel plate.The static friction angle is smallest of the formed tea against all the tea machinery materials.