球磨法制备富硒绿茶粉工艺优化
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摘要
以紫阳富硒茶成叶为原料,通过漂烫杀青、冷冻干燥和球磨等工艺制备富硒绿茶粉,在漂烫工艺中以茶叶成叶中硒元素含量为指标考察硒元素的流失情况,比较了冷冻干燥与40℃烘箱干燥的干燥效率,并选择球磨时间、研磨球大小球比和球磨转速三个因素,通过单因素和正交试验对制备工艺条件进行优化。实验结果表明,漂烫温度为100℃条件下,茶叶成叶中硒含量随漂烫时间延长而降低,由69.58μg/kg(0 s)降低至64.72μg/kg(60 s),损失率7%;16 h冷冻干燥鲜叶失水率为52.05%,40℃烘箱干燥失水率为49.52%。影响富硒绿茶粉颗粒粒径大小的因素依次为球磨时间>大小球比>球磨转速,球磨加工最优工艺为:球磨时间50 min,球磨转速800 r/min,大小球比1∶6;采用激光粒度仪及扫描电镜对其表征,球磨颗粒形态断面清晰,粒径分布均匀,D_(50)值为3.25±0.35μm,茶粉中硒含量为(63.18±4.22)μg/kg。该工艺条件下生产的富硒绿茶粉颗粒均匀,色泽翠绿,茶叶中硒元素保留度高。
Selenium-enriched green tea powder was prepared with Ziyang selenium-rich tea leaves as raw materials by blanching,freeze-drying and ball-grinding methods. The loss rate of selenium in this process was investigated,and the efficiencies of lyophilization and oven drying at 40 ℃ were compared. Grinding time,ratio of big to small ball,and rotation speed were chosen as factors,single factor and optimal orthogonal experiments were adopted to optimize the whole process. Base on the results,the amount of selenium within leaf was decreasing as time under 100 ℃,the loss rate was 7% as the weight changed from 69.58 μg/kg at 0 s to 64.72 μg/kg at 60 s. After 16 h,the water loss rate values were 52.05% in lyophilization and 49.52% at 40 ℃ by oven drying. The factors affecting particle size were following this order:grinding time>ratio of big to small balls>rotational speed. The results showed the optimal parameters of the ball-grinding method were as follows:grinding time 50 min,rotational speed 800 r/min,and ratio of big to small ball:1∶6. Laser particle size analyzer and scanning electron microscope were empolyed to characterize the size and shape of the tea powder. The results indicated the morphology of ball milling particles' section was clear,particle size distribution was uniform,D_(50) was 3.25 μm,and the selenium content in tea powder was(63.18±4.22) μg/kg. In the process condition,the selenium-enriched green tea powder had uniform granules,bright green color and high retention of selenium.
Selenium-enriched green tea powder was prepared with Ziyang selenium-rich tea leaves as raw materials by blanching,freeze-drying and ball-grinding methods. The loss rate of selenium in this process was investigated,and the efficiencies of lyophilization and oven drying at 40 ℃ were compared. Grinding time,ratio of big to small ball,and rotation speed were chosen as factors,single factor and optimal orthogonal experiments were adopted to optimize the whole process. Base on the results,the amount of selenium within leaf was decreasing as time under 100 ℃,the loss rate was 7% as the weight changed from 69.58 μg/kg at 0 s to 64.72 μg/kg at 60 s. After 16 h,the water loss rate values were 52.05% in lyophilization and 49.52% at 40 ℃ by oven drying. The factors affecting particle size were following this order:grinding time>ratio of big to small balls>rotational speed. The results showed the optimal parameters of the ball-grinding method were as follows:grinding time 50 min,rotational speed 800 r/min,and ratio of big to small ball:1∶6. Laser particle size analyzer and scanning electron microscope were empolyed to characterize the size and shape of the tea powder. The results indicated the morphology of ball milling particles' section was clear,particle size distribution was uniform,D_(50) was 3.25 μm,and the selenium content in tea powder was(63.18±4.22) μg/kg. In the process condition,the selenium-enriched green tea powder had uniform granules,bright green color and high retention of selenium.
引文
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[14]王夏冰. 磨球直径和添加剂对行星球磨行为的影响[J]. 机床与液压,2002(6):276-277.
[15]王瑞交. 钢辊磨粉机与石磨磨粉机的加工原理对比分析[J]. 当代农机,2013(12):71-72.
[16]尤明庆,苏承东.关于石转磨力学原理的注记[J]. 力学与实践,2014,36(4):520-523.
[17]谭俊峰,彭群华,林智,等. 高密度石磨粉碎对绿茶理化成分和感官品质的影响[J]. 食品科学,2010,31(17):141-142.
[2]吴传奇,张彦,李咏. 富硒酵母的药理作用研究进展[J].微量元素与健康研究,2011,28(1):56-59.
[3]焦自明,杨建雄,张小飞,等. 紫阳富硒茶中茶多糖碱溶性茶蛋白结构形貌及硒赋存形态[J]. 陕西师范大学学报:自然科学版,2012,40(1):72-76.
[4]赵静,南占东,董庆亮,等. 富硒食品的营养价值及产品质量标准探析[J].农产品加工,2018(15):59-61.
[5]张琳,何晓叶,李建科. 紫阳富硒地区茶叶中茶多酚及硒含量不同季节与叶片分布规律[J]. 农产品加工(学刊),2014(19):13-15.
[6]陈波伟,王燕,杨晓萍,等. 烫漂护绿技术制备超微绿茶粉工艺研究[J]. 食品安全质量检测学报,2018,9(2):331-335.
[7]韩宇,胡钢亮,邵胜荣,等. 不同加工工艺对超微茶粉的理化性质影响[J]. 茶叶,2017,43(2):77-80.
[8]祁丹丹,戴伟东,谭俊峰,等. 杀青方式对夏季绿茶化学成分及滋味品质的影响[J]. 茶叶科学,2016,36(1):18-26.
[9]王银华,李凯,王金戌,等. 茶叶硒含量测定及影响富硒茶硒浸出率的因素[J]. 河北科技大学学报,2006,27(2):143-145.
[10]黎梅雨,张清安,魏雪. 不同冲泡条件对紫阳富硒茶中硒溶出的影响[J]. 陕西农业科学2014,60(11):50-53.
[11]施和森. 制茶中的干热和湿热作用[J]. 茶业通报,1989(3):8-13.
[12]朱旗,施兆鹏,任春梅. 干燥方法对速溶绿茶香气的影响[J]. 中国茶叶加工,2001(2):18-20.
[13]张秒高,张平湖,陈忠正. 真空冷冻干燥技术在茶叶加工中的研究和应用进展[J]. 安徽农业科学,2014,42(30):10679-10680,10805.
[14]王夏冰. 磨球直径和添加剂对行星球磨行为的影响[J]. 机床与液压,2002(6):276-277.
[15]王瑞交. 钢辊磨粉机与石磨磨粉机的加工原理对比分析[J]. 当代农机,2013(12):71-72.
[16]尤明庆,苏承东.关于石转磨力学原理的注记[J]. 力学与实践,2014,36(4):520-523.
[17]谭俊峰,彭群华,林智,等. 高密度石磨粉碎对绿茶理化成分和感官品质的影响[J]. 食品科学,2010,31(17):141-142.