压饼处理对白茶陈化香气的影响

本文研究经压饼处理后不同等级陈化白茶散茶和饼茶香气成分的差异,探明压饼处理对陈化白茶香气的影响,为白茶加工提供科学依据。采用顶空固相微萃取(Headspace solid-phase microextraction,HS-SPME)萃取茶叶香气,通过气相质谱联用(Gas chromatography/mass spectrometer,GC-MS)进行检测。同时,采用国标GB/T 23776-2018的方法对茶叶进行感官审评。结果表明,在陈化白茶中共检出53种挥发性香气成分,其中主要有苯甲醛、苯甲醇、芳樟醇及其氧化物、苯乙醇、α-萜品醇、香叶醇、α-雪松烯、β-雪松烯、石竹烯以及雪松醇等。对比以散茶、饼茶陈化白茶的香气成分差异,发现陈化白茶压饼后芳樟醇及其氧化物、己酸甲酯与β-紫罗酮等许多花果香物质减少,其中芳樟醇及其氧化物明显下降;而雪松醇、雪松烯、酸龙脑酯与α-蒎烯等具有木香、药香物质增加,其中雪松醇与雪松烯大幅增加。压饼处理对白茶陈化香气种类和含量都有着较大的影响,使得陈化白茶饼的陈香更显,枣香、药香等特征香型更加突出,而散茶则在花果香的保留上更具优势。进一步分析不同等级陈化白茶间的香气差异,与白毫银针相比,白牡丹和寿眉压饼陈化后香气品质更佳。

Effect of Compressed Processing on the Aroma of Aged White Tea

In this study,after compressed processing,aroma components in different grades of white tea aged loose form and compressed form were compared,aiming to ascertain the effect of compressed processing on the aroma of aged white teas. The aroma components were analyzed using head space-solid phase microextraction(HS-SPME)and gas chromatography-mass spectrometry(GC-MS). Meanwhile,the national standard GB/T 23776-2018 was used for sensory evaluation of white tea. Results showed that,53 kinds of aromatic components were detected,including benzaldehyde,benzyl alcohol,linalool,linalool oxides,phenylethyl alcohol,α-terpene,geraniol,α-cedarene,β-cedarene,caryophyllene and cedrol. By comparing the aroma components of white tea aged from loose form and compressed form,it was found that many floral and fruity aroma components such as linalool and its oxides,methyl hexoate,β-ionone decreased,and the linalool and its oxides decreased significantly while cedrol,cedarene,bornyl acetate and α-copaene increased which had woody and medicinal aroma after compressed processing,and the cedrol and cedarene increased significantly. The compressed processing had a great influence on the types and contents of aroma components,which made the typical aged fragrance of white tea was more obvious after compressed processing,and the characteristic fragrance types such as jujube and medicinal fragrance were more prominent,while the aged loose tea kept more typical floral and fruity fragrance. The aroma of aged white tea of different grades was further analyzed,and for increasing the quality of aroma,White Mudan and Shoumei were more suitable for compressed processing,compared with White Silver Needle.