Analysis Of The Aroma Components And Characteristics On Hanzhong Green Tea

Green tea has become one of the most consumed tea drinks in the world due to its unique aroma and health benefits.Hanzhong is one of the largest high-quality green tea production bases in Jiangbei tea area of China;however,there are few reports on the analysis of the aroma components and characteristics of Hanzhong green tea.In this study,Xianhao,Maojian,Techao and Chaoqing green tea produced in Xixiang,Hanzhong were used as the test materials.The aroma components in Hanzhong green tea were extracted by simultaneous distillation extraction method.The aroma components and characteristics of Hanzhong green tea were analyzed and the main research contents and results are as follows.Qualitative and quantitative analysis of Hanzhong green tea was carried out by GC-MS combined with retention index method and external standard method.A total of 75 aroma components were identified in four kinds of green tea.The aroma components identified in different green teas were different.Among them,the aroma compounds identified in Hanzhong Xianhao,Maojian,Techao and Chaoqing green tea were 63,61,64 and 66 components respectively.The identified 75 aroma components are mainly composed of alcohols,esters,ketones,heterocyclics and aldehydes;among them,the alcohol compounds are the highest content of Hanzhong green tea,and the representative compounds are linalool,geraniol,phenylethyl alcohol,etc.The total aroma compounds identified in the four green teas were 19829.02?g/kg,10456.01?g/kg,13039.15?g/kg and 12314.68 ?g/kg,respectively.The total content of aroma compounds of Xianhao is the highest,Techao and Chaoqing are similar,and Maojian is low.The results showed that there were 45 common components identified in the four Hanzhong green teas.Among them,the content of jasmonone,geraniol,(Z)-hexanoic acid-3-hexenyl ester,5-octanolide,linalool oxide II,phenylethyl alcohol,linalool,4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one,indole and 2-acetylthiazole is generally high.Of the 75 compounds identified,citral and nerol were only found in Xianhao.The four kinds of green tea in Hanzhong have both the same compounds and unique components,and show certain unique differences.The aroma characteristics of Hanzhong green tea were studied by GC-O,OAV,AEDA and sensory analysis.Through GC-O analysis,a total of 32 aroma components were smelled in four kinds of Hanzhong green tea,which consisted of 13 kinds of odor attributes.According to OAV analysis,the common compounds of OAV?10 in 4 green teas are ?-ionone,geraniol,linalool oxide II,linalool oxide III,linalool,hexanal,2-acetylthiazole,4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one and 4-ethyl-2-methoxyphenol.According to AEDA analysis,the key aroma compounds common in the four green teas are ?-ionone,geraniol and linalool oxide II.The aroma characteristics of Xianhao green tea are mainly violet aroma,followed by sweet aroma,grass and floral aroma,and the caramel aroma is weak.The aroma characteristics of Maojian green tea are mainly violet aroma and floral aroma,followed by sweet aroma,grass and herb aroma.The aroma characteristics of Techao green tea are mainly violet aroma and floral aroma,followed by caramel aroma;while the aroma characteristics of Chaoqing green tea are mainly violet aroma,followed by caramel aroma and floral aroma.In summary,the aroma characteristics of the four Hanzhong green teas can be defined as: Xianhao is fragrant aroma,Maojian,Techao and Chaoqing is chestnut-like aroma,but the aroma intensity of Maojian is much lower than that of Techao and Chaoqing.Through the GC-MS analysis of the aroma components of Xianhao,Maojian,Techao and Chaoqing green tea after storage for 6 months at-18°C,4°C and room temperature,we found that there is little difference in aroma compounds between fresh tea and tea after storage,but the amount of aroma compounds is lower than that of the fresh tea,and the total content of the identified aroma compounds is mostly lower than that of the fresh tea.It can be seen that after 6 months of storage,the green tea aroma under the three storage conditions has different degrees of loss.It indicates that during the storage process,the tea is affected by the storage conditions,and the internal substances of the tea have certain oxidation,decomposition or transformation effects,which affect the quality of the stored tea.Through GC-O,OAV,AEDA and sensory analysis,the aroma characteristics of four kinds of Hanzhong green tea after storage for 6 months showed that most of the key aroma compounds in fresh tea were still perceived in the stored tea,but the aroma characteristics of green tea under storage conditions were lower than those of fresh tea.Comparing the aroma characteristics of green tea under three different storage conditions,it was found that the frozen and refrigerated green tea can maintain the aroma characteristics of the fresh tea more than the storage at room temperature.The aroma compounds and their contents in the stored tea did not change significantly,indicating that low temperature and sealed preservation tea can effectively reduce the movement and loss of aroma molecules in tea;however,there is still internal oxidative decomposition or transformation of tea aroma.Based on this,it is recommended to store fresh tea for frozen or refrigerated storage and sealing methods for the storage of tea products in small and medium-sized tea factories or consumer household storage of green tea.The results of this study can provide a scientific basis for the quality identification of Hanzhong green tea and the digital construction of tea aroma.It has certain practical significance and application value for improving the quality status and market competitiveness of Hanzhong green tea.