Evaluation Of Aroma Characteristics And Analysis Of Volatile Compounds In Nanchuan Black Tea

Nanchuan tea is a unique local tea tree variety in Chongqing city.The main production area of Nanchuan tea,which is a relatively complex group species with distinct primitive features,is distributed in the longitude range of 107°02′09″ to 107°18′06″E and the latitude range of 28°31′48″ to 28°53′16″N.The tea plants in Nanchuan exhibit obvious primitive characteristics such as vigorous growth,strong cold and disease resistance,plump buds and leaves,early germination,and high yield.Additionally,due to their abundant components,they possess a strong aroma and flavor,making them suitable for producing black tea.However,research on the sensory quality of Nanchuan black tea is still in its initial stages,and there has yet to be a comprehensive and systematic report on its aroma.Therefore,this study focuses on Nanchuan black tea,utilizing the response surface analysis method to optimize sensory description analysis conditions and develop a sensory language library applicable to Nanchuan black tea.The goal is to establish a sensory quantitative description analysis system suitable for this type of tea product.Simultaneously,this study employs GC-MS(gas chromatography-mass spectrometry)and GC(gas chromatography)to identify the key aroma components contained in Nanchuan black tea,as well as their content.Combined with quantitative descriptive analysis results,the characteristic aroma components in Nanchuan black tea are determined The main research content and achievements are as follows:1.After recruitment,screening,training,and evaluation testing,a quantitative sensory descriptive analysis sensory panel for Nanchuan black tea was formed,consisting of 9 excellent evaluators.In order to optimize the sensory evaluation conditions,30 samples of Nanchuan black tea were uniformly mixed and 20 sets of evaluation conditions were obtained by designing experiments based on the response surface methodology,with different water-tea ratios,brewing times,and entrance temperatures.The effect of different brewing conditions on the sweetness,aroma,and stability of the panel was analyzed.The optimal brewing conditions for tea with a sweetness aroma were found to be: a temperature of 92 ℃,a brewing time of 2′37″,and a water-tea ratio of 52 m L/g.The optimal brewing conditions for tea with a sweet taste were found to be: a temperature of 92 ℃,a brewing time of 2′37″,and a water-tea ratio of 68 m L/g.The brewing conditions that resulted in the best stability of the panel were found to be: a temperature of 68 ℃,a brewing time of 4′07″,and a water-tea ratio of 68 m L/g.2.The paragraph describes the evaluation of sensory attributes of Nanchuan black tea,a type of red tea,by a sensory panel.The panel consisted of nine evaluators who were selected,trained,and evaluated for their ability to evaluate tea.The panel evaluated 30 samples of Nanchuan black tea and identified 55 sensory attribute descriptors for the tea.They used these descriptors to construct a flavor wheel for the tea.The panel then analyzed the descriptors related to aroma and identified five attributes: overall aroma,sweetness aroma,roasted aroma,woody aroma,and sweet potato aroma as the quantitative descriptors for the aroma of Nanchuan black tea.The panel used these descriptors to conduct a quantitative descriptive analysis(QDA)of 30 samples of the tea.The results of the QDA showed that tea samples with higher sweet and sweet potato aromas and lower roasted aroma were more popular among people.3.Using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry,the volatile composition of Nanchuan black tea was analyzed,and a total of 112 volatile compounds were identified.Among them,alcohols and aldehydes were found to be the major types of compounds affecting the aroma of Nanchuan black tea.Through the analysis of odor activity values,seven components were screened,namely β-lonone,linalool,(e)-linalool oxide,phenylacetaldehyde,octanal,geraniol,cis-linalool oxide with an average odor activity value(OAV)> 1.It is therefore inferred that these seven substances are the key aroma components of Nanchuan black tea.Meanwhile,five substances that may contribute significantly to the aroma of Nanchuan black tea were also screened based on their odor activity values.The contents of these 12 aroma compounds in the tea infusion were determined using SPE-GC method.The results showed that the concentration ofβ-ionone in Nanchuan black tea infusion was higher than that in other types of black tea.4.To verify the sensory impact of 12 significant aromatic substances on the sweetness,sweet potato fragrance,woody aroma,and roasted aroma of Nanchuan black tea,this study conducted a QDA evaluation by adding exogenous aromatic substances to the tea infusion.Based on the influence of different exogenous aromatic substances on the aroma attributes of the tea infusion,eight aromatic substances that significantly affect the sweetness,sweet potato fragrance,woody aroma,and roasted aroma of Nanchuan black tea were identified.Among them,beta-ionone and linalool have an extremely significant impact on the sweetness of Nanchuan black tea,representing the most important characteristic sweet aroma in Nanchuan black tea.Geraniol,benzaldehyde,phenylethanol,and nonanal have a significant impact on the sweetness of Nanchuan black tea and are the main characteristic sweetness aromas in Nanchuan black tea.β-ionone and linalool also have a significant impact on the sweet potato fragrance of Nanchuan black tea and are characteristic aromatic substances in sweet potato aroma of Nanchuan black tea.In addition,trans-2-nonanal is the characteristic aromatic substance that impacts the roasted aroma of Nanchuan black tea,while oxidized linalool II is the characteristic aromatic substance that constitutes the woody aroma of Nanchuan black tea.