绿茶沉淀异物分析和碳酸氢钠对绿茶茶汤沉淀的影响

Analysis and Effect of Sodium Bicarbonate on Green Tea Precipitation

绿茶饮料沉淀现象一直是制约绿茶饮料货架期的技术瓶颈。为了减少绿茶饮料货架期沉淀的生成,采用扫描电镜-能谱分析(SEM-EDS)、红外光谱(FT-IR)以及热裂解-气相色谱-质谱联用技术(PY-GC-MS)对绿茶沉淀异物进行分析,结合测试分析结果探究纤维素酶对绿茶茶汤感官的影响,评估纤维素酶对绿茶饮料工业生产的可行性。同时,测定不同浓度(0.01%~0.06%)碳酸氢钠下绿茶茶汤pH值、浸出物浓度、茶多酚浓度、沉淀量和感官的变化,探究pH值对绿茶茶汤沉淀的影响。结果显示:绿茶沉淀异物中含有天然纤维素成分,纤维素酶对绿茶茶汤的香气和滋味感官特性影响较大,添加纤维素酶的含量越高,感官评分越低。随着碳酸氢钠含量不断增加,绿茶茶汤的pH值不断地升高,浸出物的浓度呈现下降的趋势,茶多酚浸出物的浓度呈现先减小后增大的变化趋势,沉淀量和感官评分呈现先增加后降低的趋势;结合感官审评结果表明,绿茶萃取过程中添加0.05%的碳酸氢钠的绿茶茶汤,可以保持产品良好的感官特性,有效地减少绿茶沉淀量的生成。

Green tea beverage precipitation has always been a technical bottleneck that restricts the shelf period of green tea beverage.In order to reduce precipitation of green tea beverage during shelf periods,Scanning Electron Microscopy-Energy Dispersive Spectrometer,Fourier Transform Infrared Spectoscopy and Pyrolysis Gas Chromatography Mass Spectrum were used to analyze green tea precipitation,combined with the test analysis results to explore the effect of cellulase on the sensory effects of green tea soup,and to evaluate the effect of cellulase on the industrial production of green tea beverage.At the same time,in order to explore effect of pH value on the precipitation of green tea infusion,the pH value,extract concentration,tea polyphenol concentration,precipitation amount and sensory changes of green tea infusion were measured with different concentrations(0.01%~0.06%)of sodium bicarbonate.The results showed that green tea precipitation contained natural cellulose components,and cellulase had a greater impact on the sensory properties of aroma and taste of green tea infusion.The higher the content of cellulase added,the lower the sensory score.With the continuous increase of sodium bicarbonate content,the pH value of green tea soup continued to increase,the concentration of extracts showed a downward trend,and the concentration of tea polyphenol extracts showed a trend of decreasing first and then increasing.The amount of sedimentation and sensory evaluation showed a trend of increasing first and then decreasing.Combined with the sensory evaluation results,it was shown that adding 0.05%sodium bicarbonate to the green tea soup during the green tea extraction process can maintain the good sensory properties of the product and effectively reduce the formation of green tea sediment.