Next Article in Journal
A Review on Recent Advancements of Graphene and Graphene-Related Materials in Biological Applications
Next Article in Special Issue
Beta vulgaris subsp. maritima: A Valuable Food with High Added Health Benefits
Previous Article in Journal
Modification of Nanocrystalline Porous Cu2-xSe Films during Argon Plasma Treatment
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Applied Sciences
Volume 11
Issue 2
10.3390/app11020613
applsci-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Communication

Absolute Quantitative Volatile Measurement from Fresh Tea Leaves and the Derived Teas Revealed Contributions of Postharvest Synthesis of Endogenous Volatiles for the Aroma Quality of Made Teas

by
Mingjie Chen
1,*,†,
Li Guo
2,3,†,
Huiwen Zhou
1,
Yaling Guo
3,
Yi Zhang
1,
Zhi Lin
2,
Meng Sun
1,
Wei Zeng
1 and
Hualing Wu
4
1
Henan Key Laboratory of Tea Plant Biology, College of Life Sciences, Xinyang Normal University, Xinyang 464000, China
2
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China
3
College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
4
Tea Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Laboratory of Tea Plant Resources Innovation & Utilization, Guangzhou 510640, China
*
Author to whom correspondence should be addressed.
†
Contributed equally to this work.
Appl. Sci. 2021, 11(2), 613; https://doi.org/10.3390/app11020613
Submission received: 14 December 2020 / Revised: 4 January 2021 / Accepted: 7 January 2021 / Published: 10 January 2021
(This article belongs to the Special Issue Innovative Separation Methods in Food Chemistry and Analysis)
Browse Figure
Review Reports Versions Notes

Abstract

:
Characteristic aroma is a well-appreciated feature contributing to tea quality. Although extensive studies have been made to investigate aroma biosynthesis and gene expressions during tea making processes, it remains unclear whether the endogenous volatile biosynthesis during postharvest tea processing contributes to the aroma quality of made tea. To critically evaluate this question, we used the same batch of fresh tea leaves and produced three different types of tea with different degrees of fermentation (green tea, oolong tea, and black tea). Total volatiles were extracted by solvent-assisted-flavor evaporation, then quantified by gas chromatography-flame ionization detector combined with response factor correction for quantitative measurement. Compared with fresh tea leaves, the volatile profiles of the made teas were dramatically altered, with significant loss for the majority of endogenous volatiles and simultaneous gain for non-endogenous volatiles. By calculation of odor-activity values, the potential volatiles contributing to the aroma characteristics of each tea type were identified. Our data suggest that postharvest synthesis of endogenous volatiles did not contribute to the aroma quality of made tea.

1. Introduction

Aroma is determined by the concentration and composition of various volatiles. Tea aroma characteristics affect its quality, consumer preference, and commercial value. Based on the degrees of fermentation, tea can be classified into three large categories: non-fermented green tea, semi-fermented oolong tea, and fully fermented black tea [1,2]. Tea making starts with fresh tea leaves as the raw material, which has a grassy odor. During tea processing the volatile profiles are altered and eventually form the characteristic aroma [3,4,5,6]. Volatiles retained in the made teas are either derived from fresh tea leaves or newly synthesized during postharvest tea making. Here, for clarity, the volatiles existed in the preharvest tea leaves are named as endogenous volatiles (EVs) of fresh tea leaves. Accordingly, the non-endogenous volatiles (NEVs) refer to those that are not detected from the fresh tea leaves but present in made teas.
The quality of tea depends first and foremost, on the quality of the raw material and rational application of technological processes. EVs are affected by the tea cultivar, growing environment, and agronomic practices [7,8,9,10]. It is generally assumed that EVs synthesis during tea making processes contribute significantly to the aroma characteristics of made teas; extensive efforts have been invested to characterize EVs biosynthesis pathways and related gene expressions during postharvest tea making, in the hope to find new strategies to improve the aroma quality of made teas [11,12,13,14,15,16,17]. In most of these studies, volatiles were measured in a relative- or semi- quantitative manner; volatiles of fresh tea leaves versus those of made teas were not quantitatively extracted and compared. Thus, it remains unclear whether these synthesized EVs really contribute to the aroma quality of made teas. In this study, we started with the same batch of fresh tea leaves (Camellia sinensis cv Tieguanyin), and made three different types of tea (green tea, oolong tea, and black tea) according to respective standard tea processing methods (Supplementary Figure S1). Their volatiles were extracted by a solvent-assisted-flavor evaporation, then quantified by gas chromatography-flame ionization detector (GC-FID) combined with FID response factor correction. We found that compared to fresh tea leaves, the volatile profiles of made teas were dramatically altered; the majority of the EVs contents were reduced, while many NEVs accumulated simultaneously. The total volatile contents of made teas were significantly lower than those of the fresh tea leaves. By calculating the odor-activity value (OAV), the potential volatiles contributing to the aroma characteristics of each tea type were identified. Our data suggest that EVs synthesis during postharvest tea processing did not make significant contributions to the aroma quality of made tea.

2. Materials and Methods

2.1. Sample and Chemicals

One bud and three leaves were plucked from Camellia sinensis cv Tieguanyin on 29 April 2017, then processed into green tea, oolong tea, and black tea according to respective standard tea making methods (Supplementary Figure S1). The tea leaves were withered under sunlight for 30 min, then moved indoors to cool down. To make green tea, tea leaves were heat deactivated. To make oolong tea, leaves were subjected to turning-over followed by spreading. This turning-over/spreading cycle was repeated four times, the time for the first turning-over to the fourth turning-over lasted for 3-, 4-, 8-, and 10- min, respectively. The spreading lasted for 2–3 h following each turning-over treatment. After the completion of the 4th turning-over/spreading cycle, the tea leaves were heat deactivated. Heat deactivation was conducted in an electric-powered pan, the leaf temperature was monitored, and the deactivation was stopped once leaf temperature reached to 80–85 °C. The leaves were rolled for 35 min, followed by a drying treatment. To make black tea, tea leaves were withered indoors for 18 h, then rolled for one hour, followed by fermentation for 4 h before drying. The drying was performed at 100 °C for 10 min followed by 90 °C for 1 h. Before tea making, a portion of the fresh tea leaves were frozen in liquid nitrogen as the control sample.
Diethyl ether (analytical grade, 99.9%) and anhydrous sodium sulfate (analytical grade, 99%) were ordered from Sino Pharm, Shanghai, China; ethyl caprate (GC ≥ 98%) was purchased from Sigma, St. Louis, MO, USA.

2.2. Volatile Extraction

Tea volatiles were extracted as before [18]. The water contents from the fresh tea leaves varied between 65% to 75% depending on the tenderness of the tea leaves, germplasms and plucking seasons. In this study, 8 g of fresh tea leaves and 2 g of dry tea were used for volatile extraction. Tea leaves were frozen with liquid nitrogen and powdered, the tea powder was transferred into a glass stoppered flask. Forty milliliters of diethyl ether and 64.5 µg of ethyl caprate internal standard were added. To absorb water, 8 g (for fresh tea leaves) or 0.5 g (for dry tea) anhydrous sodium sulfate was also added. The tea powder was extracted under stirring (200 rpm) for 2 h. The organic phase was collected, then distilled through a solvent-assisted-flavor-evaporation device (SAFE). The detailed SAFE operation followed the method described by Chen et al. (2020) [18]. The volume for the distillation flask and the receiver flask was 500 mL. The volatile distillate was collected, aliquot into 8-mL glass tubes, concentrated in a rotary evaporator to about 1.5 mL, then transferred into labeled 2-mL GC vials, and further concentrated in a rotary evaporator. The volume was closely monitored; the concentration step was stopped immediately once the volume was slightly below the 500 μL marker line. A small volume of diethyl ether was added to make the total volume reach 500 μL. Fresh leaves and oolong tea had four biological replicates, whereas green tea and black tea had three biological replicates.

2.3. Volatile Identification and Quantification

Volatiles were analyzed as described before [18,19]. Briefly, 1 µL of sample was injected into a capillary column (RXi-5SiIMS column, 30 m × 0.25 mm × 0.25 µm) in a splitless mode for GC-MS and GC-FID analysis. The oven temperature program was initiated at 50 °C for 2 min, raised 5 °C min−1 to 180 °C, and held 2 min; then raised 10 °C min−1 to 230 °C, and held 5 min before returning to 50 °C for the next sample. Injector, ion source, interface, and FID temperatures were 250, 230, 270, and 230 °C, respectively. The flow rates of hydrogen, nitrogen, and zero air were 40, 30, and 400 mL min−1, respectively, and helium was used as the carrier gas with a flow rate of 1.0 and 1.7 mL min−1 for GC-MS and GC-FID, respectively. Zero air is a highly purified air in which almost all the hydrocarbon is removed. The electron ion source was set at 70 eV, and the chromatograms were recorded by monitoring the total ion current in the mass range of 45–600 m/z. Since each compound has its own ionization and fragmentation in the MS detector [20], thus, various volatiles cannot be reliably quantified by comparing with a single internal standard. In this study, MS data was used for volatile identification by comparing MS spectral with the NIST14 database, and further confirmed by their reported retention index; volatiles were quantified from FID data by normalizing to the internal standard peak area. To calibrate the FID response differences for individual volatiles, FID response factors relative to the internal standard were calculated and used for further normalization (Supplementary Table S1). The fresh leaf water contents were determined by the National Standard of P. R. China (GB/T 5009-2016), then used to convert fresh leaf weight into dry mass. The volatile contents were normalized to dry mass. To convert the retention time into the retention index, n-alkanes (C9–C25) were analyzed under the same condition, and the data was used to convert the retention time into the retention index (RI) by the formula: RI = 100 × [(tR − tRz)/(tR(z + 1) − tRz) + z]. Where z is the carbon number of the alkane standard, tRz and tR(z + 1) represent the retention times of z and z + 1 alkane standards, and tR is the retention time of tea volatile that falls between tRz and tR(z + 1).

2.4. Calculation of Volatile Concentration from Tea Infusion and Odor-Activity Value

Organoleptic assessment was made according to the National Standard of P. R. China (GB/T 23776-2018)—Methodology for Sensory Evaluation of Tea. In a standard organoleptic assessment by a trained tea taster, the oolong tea infusion was prepared by extracting 5 g of oolong dry tea in 110 mL of boiling water; in contrast, the green tea or black tea infusion was prepared by extracting 3 g of dry tea in 150 mL of boiling water. To evaluate the volatile contribution to the aroma characteristics of tea infusion, ideally their concentrations in the tea infusion are directly measured. However, to fully recover volatiles from the simulated standard tea infusion preparation is technically challenging, since a considerable amount of volatiles easily evaporate into the air space and get lost; to add this complexity, it has been reported that during tea infusion preparation, under the action of hot water, some new volatiles are formed from its glycosidically bound precursors [21]. To avoid these issues, we assumed that all the volatiles from dry tea were extracted into the tea infusion during the tea infusion preparation. Based on the absolute volatile contents from dry tea and the tea mass to water ratio, the volatile concentrations in the tea infusion could be calculated. The odor detection threshold in water was obtained from literature, then used to calculate odor activity value.

2.5. Statistical Analysis

A Student’s t-test with two-tailed equal variance was performed to determine the significance (p < 0.05).

3. Results and Discussion

The volatiles from fresh tea leaves, green tea, oolong tea, and black tea were extracted in diethyl ether, then separated from non-volatile substances and analyzed by GC-MS and GC-FID (Supplementary Figures S2 and S3). In total; 31, 32, 27, and 31 volatiles were identified from respective samples (Table 1). Among the 31 EVs of fresh tea leaves, there were 19, 15, and 14 volatiles detected from green tea, oolong tea, and black tea, respectively. Among the 32 green tea volatiles, there were 17 and 15 volatiles commonly detected from oolong tea and black tea, respectively. There were 14 volatiles commonly detected between oolong tea and black tea (Table 1, Supplementary Figure S4).
Among the 31 EVs detected from fresh tea leaves, nine volatiles were below the detection threshold from these three types of made tea: phenylethyl alcohol, germacrene D, nerolidol isobutyrate, γ-cadinene, trans-calamenene, cis-cadina-1(2),4-diene, and three unidentified volatiles. Meanwhile, nine volatiles from fresh tea leaves were commonly detected from these three types of made teas. In four of them, β-cis-ocimene, cis-linalool oxide (furanoid), trans-linalool oxide (furanoid), and linalool, their contents from made teas only accounted for 0.8–14% of that from fresh tea leaves. The other five volatiles, including E-nerolidol, (Z)- 3-hexenyl benzoate, hexyl benzoate, neophytadiene, and caffeine, were not significantly different from that of fresh tea leaves except that the E-nerolidol contents from green tea and oolong tea as well as the neophytadiene and caffeine contents from black tea were significantly higher than that of the fresh tea leaves. The remaining 13 volatiles were either detected from only one or two types of made teas; their contents were significantly lower than that of fresh tea leaves except cis-jasmone and β-caryophyllen, which were similar between fresh tea leaves and green tea or oolong tea (Table 1). The total volatile contents for fresh tea leaves, green tea, oolong tea, and black tea were 76.13 ± 11.66, 7.73 ± 0.71, 5.77 ± 0.74, 7.80 ± 1.83 μg. g−1 dry weight (DW), respectively. These data demonstrated that the tea making processes were characterized by the significant loss for most of the EVs. Thus, their synthesis during postharvest tea making processes would not contribute significantly to the aroma quality of made tea products. It remains unclear why and how these EVs were lost during tea making processes. A detailed quantitative volatile measurement at each processing step is required to resolve this issue. It is obvious that the abundant volatiles from fresh tea leaves were lost more compared to less abundant volatiles (Table 1). We speculated that there are two factors that could affect volatile retention. One was that the leaf cell structure was disrupted by the tea making process, which may reduce the leaf’s volatile holding capacity, and thus result in the evaporation of the abundant volatiles. On the other hand, drying should result in significant volatile loss since it was performed at 90–100 °C, which was above the boiling points for many tea volatiles. Under this pathway, the amounts of volatile loss would depend on the drying temperature, time, and the volatility of individual tea aroma.
A major difference between green tea and oolong tea making technology was the “turning over” step of oolong tea (Supplementary Figure S1). Some volatile contents from oolong tea, including hotrienol, dodecane, 2,6-dimethyl-3,7-octadiene-2,6-diol, hexyl butanoate, 1,3-bis(1,1-dimethylethyl) benzene, 2,5-dihydro-2,5-dimethoxyfuran, hexyl hexanoate, (E)-β-farnesene, δ-cadinene, (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, and cis-3-hexanyl n-octanoate, were significantly higher than that of green tea (Table 1). This suggested that the “turning over” treatments could activate these volatile syntheses. Meanwhile, other volatile contents from oolong tea, including (E)-4,8-dimethylnona-1,3,7-triene, (Z)-3-hexenyl butanoate, methyl salicylate, (E)-geraniol, cis-3-hexenyl hexanoate, β-caryophyllen, trans-β-ionone, cis-jasmin lactone, naphthalene, (E)-γ-bisabolene, α-cadinene, germacrene B, E-2-hexenyl benzoate, methyl jasmonate, and cis-3-hexenyl salicylate, were lower than that of green tea, suggesting that the “turning over” step could also facilitate these volatile’s evaporation.
There were 13, 12, and 17 volatiles detected from green tea, oolong tea, and black tea respectively, but below the detection limit from fresh tea leaves (Table 1, Supplementary Figure S2). These data demonstrated that postharvest tea processing facilitate NEVs formation and accumulation. Interestingly, oolong tea was generally regarded to be more aromatic than green tea or black tea [22]. However, its total aroma contents were significantly lower than that of green tea or black tea (Figure 1). Thus, the total volatile contents did not positively correlate with their aroma quality. Other factors, such as the volatile compositions, could play a larger role to influence tea’s aroma characteristics.
To identify which volatiles could confer an aroma note in a standard sensory evaluation, the odor-activity value (OAV) was calculated. The odor activity values (OAVs) are the ratios of concentration found in the food matrix to its odor detection threshold [23]. The odor detection threshold is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell. The OAV is commonly used to estimate odor potency, their values from fresh tea leaves and made teas are listed in the order of retention time from low to high in Table 2. The volatiles with OAV > 1 were generally regarded as contributors to the aroma characteristics. Thus, linalool, (E)-geraniol, indole, cis-jasmone, trans-β-Ionone, and α-farnesene could be the potential contributors to the aroma quality of Tieguanyin green tea; linalool, indole, cis-jasmone, and α-farnesene could be the potential contributors to the aroma quality of Tieguanyin oolong tea; linalool, trans-linalool oxide (pyranoid), 1-dodecanol, and trans-β-ionone could be the potential contributors to the aroma quality of Tieguanyin black tea. Interestingly, among these potential aroma contributors, linalool, (E)-geraniol, and indole are EVs. Although their contents in the made teas were significantly lower than that of fresh tea leaves, they still retained a sufficient amount contributing to the aroma characteristics in the made tea. On the other hand, tran-β-ionone, α-farnesene, trans-linalool oxide (pyranoid), and 1-dodecanol, which were NEVs produced in sufficient amount during tea processing, become aroma contributors.
Although a 100% volatile recovery from dry tea to tea infusion is not plausible, considering that most of these OAVs were larger than two, thus, even with a 50% recovery rate, the OAVwould still be larger than one, and contributed to the characteristic aroma of tea infusion. Although linalool, (E)-geraniol, and indole were present in fresh leaves at much higher contents compared to made teas (Table 1), the fresh tea leaves did not show the pleasant aroma as the made tea did. One possibility could be that fresh tea leaves also contained other unpleasant volatiles which created masking effects. Removing or reducing these endogenous unpleasant volatiles could be an important aspect for tea processing; another possibility could be that some volatiles showed totally different characteristics in a concentration-dependent manner. One well-characterized example was indole; at very low concentrations indole had a flowery smell [39], however, in high concentrations it smelled animal-like [40]. Under our experimental conditions, only about 14% of the indole from fresh tea leaves was retained in green tea or oolong tea (Table 1). However, their OAV values in green tea and oolong still were in the ranges of 14.7–35.2 (Table 2), thus, it could confer a flowery smell to green tea or oolong tea. Four contributing volatiles, including trans-pyranoid linalool oxide, 1-dodecanol, trans-β-ionone, and α-farnesene were only detected from certain types of made tea and with large difference in odor-activity value, suggesting that tea processing technologies determined specific NEVs formation and retention, and thus shaped the characteristic aroma for each tea type.
Previously Zhang et al. (2013) applied simultaneous distillation extraction method and isolated volatiles from green teas, oolong teas, and black teas with various origins, then semi-quantified by two-dimensional GC-TOFMS, through multivariate data analysis the compounds with a significant difference were defined [41]. Several volatiles were commonly detected from these two studies; they can be divided into two groups. The first group showed similar changing trends among green tea, oolong tea and black tea between these two studies, including cis-linalool oxide (furanoid), trans-linalool oxide (furanoid), benzyl nitrile, methyl salicylate, 2,6-dimethyl-3,7-octadien-2,6-diol, indole, cis-jasmone, α-farnesene, and nerolidol; in contrast, the second group showed different changing trends among green tea, oolong tea, and black tea between these two studies, including (E)-Hotrienol, (E)-4,8-dimethyl-nona-1,3,7-triene, phenylethyl alcohol, cis-3-hexenyl hexanoate, jasmin lactone, and methyl jasmonate. Since in the previous study green tea, oolong tea and black tea came from different sources, and different cultivars may be used to produce them, this could account for the difference between these two studies. To support this notion, even within same tea type large variations have been reported in previous study [41].

4. Conclusions

In this study, we successfully produced green tea, oolong tea, and black tea from the same batch of fresh leaves by following respective standard tea processing methods; tea volatiles were then extracted and quantified by GC-FID, further calibrated by FID response factor, and compared with that of fresh leaves. We found that total volatile contents from made teas were significantly reduced compared to the contents of fresh tea leaves; most of the EVs from made teas were lower in amounts than those of fresh tea leaves. Meanwhile, specific NEVs were produced during tea making processes. Calculation of odor-activity values identified that some EVs and NEVs both contributed to the characteristic aroma of made teas. Our data suggest that the postharvest endogenous volatile synthesis during tea making processes were not important to shape the characteristic aroma of made tea.

Supplementary Materials

The following are available online at https://www.mdpi.com/2076-3417/11/2/613/s1, Figure S1: Diagram presentation of standard tea making processes for green tea, oolong tea, and black tea, Figure S2: GC-MS chromatography of fresh tea leaves, green tea, oolong tea and black tea, Figure S3: GC-FID chromatography of fresh tea leaves, green tea, oolong tea and black tea, Figure S4: Volatile distributions among fresh tea leaves, green tea, oolong tea, and black tea, Table S1: Tea volatile FID response factor relative to ethyl caprate.

Author Contributions

Conceptualization, M.C.; methodology, M.C.; validation, H.Z., M.S. and W.Z.; formal analysis, M.C.; investigation, L.G.; resources, Z.L. and H.W.; data curation, L.G.; writing—original draft preparation, M.C.; writing—review and editing, W.Z., and H.W.; visualization, Y.Z.; supervision, Y.G.; project administration, M.C. and Y.G.; funding acquisition, H.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by the Key-Area Research and Development Program of Guangdong Province (2020B020220004), the Science and Technology Innovation Fund of Fujian Agriculture and Forestry University (CXZX2017350), the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2014-TRICAAS), and the Earmarked Fund for China Agricultural Research System (CARS-19).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available in Supplementary Material here.

Acknowledgments

The authors want to thank Fuqing Wuli Ecological Agriculture Science and Technology Ltd. for providing the fresh tea leaves and graduate students Wei Wang and Zan Wang for helping with tea making.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

References

  1. Xia, T. Tea Classification. Tea Making; China Agriculture Press: Beijing, China, 2016. [Google Scholar]
  2. Zheng, X.; Nie, Y.; Gao, Y.; Huang, B.; Ye, J.; Lu, J.; Liang, Y. Screening the cultivar and processing factors based on the flavonoid profiles of dry teas using principal component analysis. J. Food Comp. Anal. 2018, 67, 29–37. [Google Scholar] [CrossRef]
  3. Mittler, R. Abiotic stress, the field environment and stress combination. Trends Plant. Sci. 2006, 11, 15–19. [Google Scholar] [CrossRef] [PubMed]
  4. Yang, Z.Y.; Kobayashi, E.; Katsuno, T.; Asanuma, T.; Fujimori, T.; Ishikawa, I.; Tomomura, M.; Mochizuki, K.; Watase, T.; Nakamura, Y.; et al. Characterization of volatile and non-volatile metabolites in etiolated leaves of tea (Camellia sinensis) plants in the dark. Food Chem. 2012, 135, 2268–2276. [Google Scholar] [CrossRef] [PubMed]
  5. Fu, X.M.; Chen, Y.Y.; Mei, X.; Katsuno, T.; Kobayashi, E.; Dong, F.; Watanabe, N.; Yang, Z.Y. Regulation of formation of volatile compounds of tea (Camellia sinensis) leaves by single light wavelength. Sci. Rep. 2015, 5, 16858. [Google Scholar] [CrossRef] [PubMed]
  6. Yener, S.; Sánchez-López, J.A.; Granitto, P.M.; Cappellin, L.; Märk, T.D.; Zimmerman, R.; Bonn, G.; Yeretzian, C.; Biasioli, F. Rapid and direct volatile compound profiling of black and green teas (Camellia sinensis) from different countries with Ptr-ToF-ms. Talanta 2016, 152, 45–53. [Google Scholar] [CrossRef] [PubMed]
  7. Dong, F.; Yang, Z.Y.; Baldermann, S.; Sato, Y.; Asai, T.; Watanabe, N. Herbivore-induced volatiles from tea (Camellia sinensis) plants and their involvement in intraplant communication and changes in endogenous nonvolatile metabolites. J. Agri. Food Chem. 2011, 59, 13131–13135. [Google Scholar] [CrossRef] [PubMed]
  8. Cai, X.M.; Sun, X.L.; Dong, W.X.; Wang, G.C.; Chen, Z.M. Herbivore species, infestation time, and erbivoredensity affect induced volatiles in tea plants. Chemoecology 2014, 24, 1–14. [Google Scholar] [CrossRef]
  9. Mei, X.; Liu, X.Y.; Zhou, Y.; Wang, X.Q.; Zeng, L.T.; Fu, X.M.; Li, J.L.; Tang, J.C.; Dong, F.; Yang, Z.Y. Formation and emission of linalool in tea (Camellia sinensis) leaves infested by tea green leafhopper (Empoasca (matsumurasca) onukii matsuda). Food Chem. 2017, 237, 356–363. [Google Scholar] [CrossRef]
  10. Zeng, L.T.; Zhou, Y.; Fu, X.M.; Liao, Y.Y.; Yuan, Y.F.; Jia, Y.X.; Dong, F.; Yang, Z.Y. Biosynthesis of jasmine lactone in tea (Camellia sinensis) leaves and its formation in response to multiple stresses. J. Agri. Food Chem. 2018, 66, 3899–3909. [Google Scholar] [CrossRef]
  11. Cao, F.R.; Liu, K.B.; Liu, C.Y.; Wang, D.L. Studies on the induction of aromatic constituents in fresh leaves of Lingtou Dancong tea by low temperature stress (In Chinese). Front. Agri. China 2006, 1, 81–140. [Google Scholar] [CrossRef]
  12. Cho, J.Y.; Mizutani, M.; Shimizu, B.; Kinoshita, T.; Ogura, M.; Tokoro, K.; Lin, M.L.; Sakata, K. Chemical profiling and gene expression profiling during the manufacturing process of Taiwan oolong tea Oriental beauty. Biosci. Biotech. Biochem. 2007, 71, 1476–1486. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  13. Jang, J.; Yang, Y.C.; Zhang, G.H.; Chen, H.; Lu, J.L.; Du, Y.Y.; Ye, J.H.; Ye, Q.; Borthakur, D.; Zheng, X.Q. Effect of ultraviolet B on release of volatiles in tea leaf. Int. J. Food Prop. 2010, 13, 608–617. [Google Scholar] [CrossRef]
  14. Yang, Z.Y.; Mochizuki, K.; Watase, T.; Kobayashi, E.; Katsuno, T.; Asanuma, T.; Tomita, K.; Morita, A.; Suzuki, T.; Nakamura, Y. Influences of light emitting diodes irradiations and shade treatments on volatile profiles and related metabolites of leaves of tea (Camellia sinensis) plants and postharvest tea leaves. In Advances and Challenges in Flavor Chemistry & Biology; Hofmann, T., Meyerhof, W., Schieberle, P., Eds.; Deutsche Forschungsanstalt Lebensmittelchemie: Freising, Germany, 2010; pp. 207–213. [Google Scholar]
  15. Gui, J.D.; Fu, X.M.; Zhou, Y.; Katsuno, T.; Mei, X.; Deng, R.F.; Xu, X.L.; Zhang, L.Y.; Dong, F.; Watanabe, N.; et al. Does enzymatic hydrolysis of glycosidically bound volatile compounds really contribute to the formation of volatile compounds during the oolong tea manufacturing process? J. Agri. Food Chem. 2015, 63, 6905–6914. [Google Scholar] [CrossRef] [PubMed]
  16. Zeng, L.T.; Zhou, Y.; Gui, J.D.; Fu, X.M.; Mei, X.; Zhen, Y.P.; Ye, T.X.; Du, B.; Dong, F.; Watanabe, N. Formation of volatile tea constituent indole during the oolong tea manufacturing process. J. Agr. Food Chem. 2016, 64, 5011–5019. [Google Scholar] [CrossRef] [PubMed]
  17. Zhou, Y.; Zeng, L.T.; Liu, X.Y.; Gui, J.D.; Mei, X.; Fu, X.M.; Dong, F.; Tang, J.C.; Zhang, L.Y.; Yang, Z.Y. Formation of (E)-nerolidol in tea (Camellia sinensis) leaves exposed to multiple stresses during tea manufacturing. Food Chem. 2017, 231, 78–86. [Google Scholar] [CrossRef] [PubMed]
  18. Chen, X.B.; Zhang, Y.; Du, Z.H.; Liu, R.M.; Guo, L.; Chen, C.S.; Wu, H.L.; Chen, M.J. Establishing a quantitative volatile measurement method in tea by integrating sample extraction method optimizations and data calibration. Flavor Fragr. J. 2020, 36, 64–74. [Google Scholar] [CrossRef]
  19. Liu, R.M.; Du, Z.H.; Zhang, Y.; Shi, Y.Y.; Chen, X.B.; Lin, L.; Xiong, Y.M.; Chen, M.J. Volatile component quantification in combination with putative gene expression analysis reveal key players in aroma formation during fruit ripening in Carica papaya cv Hong fei. Postharvest Bio. Tech. 2019, 158, 110987. [Google Scholar] [CrossRef]
  20. Hatsis, P.; Waters, N.J.; Argikar, U.A. Implications for metabolite quantification by mass spectrometry in the absence of authentic standards. Drug Metab Dispos. 2017, 45, 492–496. [Google Scholar] [CrossRef]
  21. Kinoshita, T.; Hirata, S.; Yang, Z.; Baldermann, S.; Kitayama, E.; Matsumoto, S.; Suzuki, M.; Fleischmann, P.; Winterhalter, P.; Watanabe, N. Formation of damascenone derived from glycosidically bound precursors in green tea infusions. Food Chem. 2010, 123, 601–606. [Google Scholar] [CrossRef] [Green Version]
  22. Yang, Z.Y.; Baldermann, S.; Watanabe, N. Recent studies of the volatile compounds in tea. Food Res. Int. 2013, 53, 585–599. [Google Scholar] [CrossRef]
  23. Cadwallader, K. Measuring cheese flavor. In Improving the Flavour of Cheese; Weimer, B.C., Ed.; Woodhead Publishing: Cambridge, UK, 2007; pp. 401–417. [Google Scholar]
  24. Tamura, H.; Boonbumrung, S.; Yoshizawa, T.; Varanyanond, W. The volatile constituents in the peel and pulp of a green Thai mango, khieo sawoei Cultivar (Mangifera indica L.). Food Sci. Technol. Res. 2001, 7, 72–77. [Google Scholar] [CrossRef] [Green Version]
  25. Pino, J.A.; Quijano, C.E. Study of the volatile compounds from plum (Prunus domestica L. cv. Horvin) and estimation of their contribution to the fruit aroma. Ciênc. Tecnol. Aliment. Camp. 2012, 32, 76–83. [Google Scholar] [CrossRef] [Green Version]
  26. Slaghenaufi, D.; Boscaini, A.; Prandi, A.; Cin, A.D.; Zandonà, V.; Luzzini, G.; Ugliano, M. Influence of different modalities of grape withering on volatile compounds of young and aged corvina wines. Molecules 2020, 25, 2141. [Google Scholar] [CrossRef] [PubMed]
  27. Kesharwani, P. Nanotechnology-Based Targeted Drug Delivery Systems for Lung Cancer; Academic Press: Cambridge, MA, USA, 2019; pp. 95–121. [Google Scholar]
  28. Gong, X.; Han, Y.; Zhu, J.; Hong, L.; Zhu, D.; Liu, J.; Zhang, X.; Niu, Y.; Xiao, Z. Identification of the aroma-active compounds in Longjing tea characterized by odor activity value, gas chromatography- olfactometry, and aroma recombination. Int. J. Food Prop. 2017, 20, S1107–S1121. [Google Scholar] [CrossRef]
  29. Cliff, M.; Stanich, K.; Trijillo, J.M.; Toivonen, P.; Forney, C.F. Determination and prediction of odor thresholds for odor active volatiles in a natural apple juice matrix. J. Food Qual. 2011, 34, 177–186. [Google Scholar] [CrossRef]
  30. Czerny, M.; Christlbauer, M.; Christlbauer, M.; Fischer, A.; Granvogl, M.; Hammer, M.; Hartl, C.; Hernandez, N.M.; Schieberle, P. Re-investigation on odour thresholds of key food aroma compounds and development of an aroma language based on odour qualities of defined aqueous odorant solutions. Eur. Food Res. Technol. 2008, 228, 265–273. [Google Scholar] [CrossRef]
  31. Han, Z.X.; Rana, M.M.; Liu, G.F.; Gao, M.J.; Li, D.X.; Wu, F.G.; Li, X.B.; Wan, X.C.; Wei, S. Data on green tea flavor determinants as affected by cultivars and manufacturing processes. Data Brief. 2017, 10, 492–498. [Google Scholar] [CrossRef]
  32. Ito, Y.; Kubota, K. Sensory evaluation of the synergism among odorants present in concentrations below their odor threshold in a Chinese jasmine green tea infusion. Mol. Nutr. Food Res. 2005, 49, 61–68. [Google Scholar] [CrossRef]
  33. Buttery, R.G.; Guadagni, D.G.; Ling, L.C. Volatile aroma components of cooked Artichoke. J. Agric. Food Chem. 1978, 26, 791–793. [Google Scholar] [CrossRef]
  34. Risner, D.; Tomasino, E.; Hughes, P.; Meunier-Goddik, L. Volatile aroma composition of distillates produced from fermented sweet and acid whey. J. Dairy Sci. 2019, 102, 202–210. [Google Scholar] [CrossRef] [Green Version]
  35. Apps, P.J.; Weldon, P.J.; Kramer, M. Chemical signals in terrestrial vertebrates: Search for design features. Nat. Prod. Rep. 2015, 32, 1131–1153. [Google Scholar] [CrossRef] [PubMed]
  36. Miller, G.H. Whisky Science; Springer Nature: Cham, Switzerland, 2019; pp. 421–468. [Google Scholar] [CrossRef]
  37. van Gemert, L.J. Compilations of Odour Threshold Values in Air, Water and Other Media; Van Setten Kwadraat: Houten, The Netherlands, 2003. [Google Scholar]
  38. Burdock, G.A. Fenaroli’s Handbook of Flavor Ingredients; CRC Press: Boca Raton, FL, USA, 2009; Available online: https://www.routledgehandbooks.com/doi/10.1201/9781439847503-c3 (accessed on 1 January 2020).
  39. Shinoda, R.; Takahashi, K.; Ichikawa, S.; Wakayama, M.; Kobayashi, A.; Miyagawa, S.; Uchimura, T. Using SPME-GC/REMPI-TOFMS to measure the volatile odor-active compounds in freshly cooked rice. ACS Omega. 2020, 5, 20638–20642. [Google Scholar] [CrossRef] [PubMed]
  40. Wang, Z.; Xiao, Q.; Zhuang, J.; Feng, T.; Ho, C.; Song, S. Characterization of aroma-active compounds in four yeast extracts using instrumental and sensory techniques. J. Agric. Food Chem. 2020, 68, 267–278. [Google Scholar] [CrossRef] [PubMed]
  41. Zhang, L.; Zeng, Z.; Zhao, C.; Kong, H.; Lu, X.; Xu, G. A comparative study of volatile components in green, oolong and black teas by using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry and multivariate data analysis. J. Chrom. A 2013, 1313, 245–252. [Google Scholar] [CrossRef] [PubMed]
Applsci 11 00613 g001 550
Figure 1. Total volatile contents from fresh leaves, green tea, oolong tea, and black tea. Data are expressed as average ± standard deviation. Different letters indicates statistically significant (p < 0.05).
Figure 1. Total volatile contents from fresh leaves, green tea, oolong tea, and black tea. Data are expressed as average ± standard deviation. Different letters indicates statistically significant (p < 0.05).
Applsci 11 00613 g001
Table
Table 1. Volatile contents from fresh tea leaves, green tea, oolong tea, and black tea.
Table 1. Volatile contents from fresh tea leaves, green tea, oolong tea, and black tea.
Boiling Point (°C)Aroma DescriptionsContents (µg. g−1 DW)
RT (min)RIlitRIexpIdentificationFresh Leaves (n = 4)Green Tea (n = 3)Oolong Tea (n = 4)Black Tea (n = 3)
8.966 960unknown 1nfnf2.45 ± 1.19ndndnd
9.344 983unknown 2nfnf6.47 ± 2.05ndndnd
10.31 1022unknown 3nfnf1.26 ± 0.27ndndnd
10.6311028.91031β-cis-ocimene175.2Fruity, floral4.71 ± 1.48 a0.10 ± 0.03 b0.11 ± 0.03 b0.05 ± 0.01 c
11.3881075.11079.4cis-linalool oxide (furanoid)188Fresh, floral3.55 ± 0.51 a0.12 ± 0.03 b0.12 ± 0.03 b0.41 ± 0.10 c
11.8761083.31080.1trans-linalool oxide (furanoid) 222.6flower5.94 ± 0.98 a0.13 ± 0.04 b0.13 ± 0.03 b0.86 ± 0.21 c
12.27210991095.7Linalool 199flower, lavender23.14 ± 2.09 a0.23 ± 0.06 b0.19 ± 0.04 b1.06 ± 0.27 c
12.4271106.81104Hotrienol80–84Fruityndnd0.42 ± 0.07 and
12.69111131109(E)-4,8-dimethylnona-1,3,7-triene 81nf3.47 ± 0.81 a0.14 ± 0.03 bndnd
13.38311281124.3Benzyl nitrile190.7pungent smell0.32 ± 0.03 a0.17 ± 0.04 b0.20 ± 0.08 bnd
14.4751114.91113.1Phenylethyl alcohol 219Fresh, rose aroma0.14 ± 0.02 andndnd
14.6041164.71162(Z)-3-Hexenyl butanoate 98Aroma like apple and grass 0.45 ± 0.09 a0.27 ± 0.06 bnd0.22 ± 0.07 b
14.67711711174trans-pyranoid linalool oxide 201–202Earthyndndnd0.41 ± 0.07 a
14.86511801178Dodecane 216nf0.88 ± 0.19 and0.10 ± 0.02 b0.14 ± 0.03 b
15.10711871184.1Methyl salicylate 223.3Minty flavor11.04 ± 1.51 a0.08 ± 0.02 bnd0.45 ± 0.12 c
15.386118911882,6-dimethyl-3,7-octadiene-2,6-diol284pungent and bad smellndnd0.11 ± 0.03 and
16.2311191.51190Hexyl butanoate205Green, fruity0.56 ± 0.10 and0.08 ± 0.02 b0.08 ± 0.03 b
16.2521200.912034-methylpentyl 2-methylbutanoatenfnfndndnd0.12 ± 0.03 a
16.4181236.312,331Hexyl 2-methyl butanoate217–219Green, fruityndndnd0.11 ± 0.03 a
16.89912531250(E)- geraniol 230rose, floral2.30 ± 0.77 a0.14 ± 0.06 bndnd
17.22124912541,3-bis(1,1-dimethylethyl)benzene106–107nfndnd0.09 ± 0.01nd
17.595126012612,5-dihydro-2,5-dimethoxyfuran160–162nfndnd0.12 ± 0.02nd
18.0331298.41301.6Indole253–254mothball, burnt5.19 ± 0.81 a0.73 ± 0.15 b0.78 ± 0.18 bnd
20.51613331330cis-3-hexenyl hexanoate115Tender, fresh and clean aroma1.05 ± 0.14 a0.26 ± 0.06 bndnd
20.67913681370trans-2-hexenyl hexanoate79fruitynd0.23 ± 0.05 a0.20 ± 0.02 a0.51 ± 0.11 b
20.75313811378Hexyl hexanoate246fruitynd0.06 ± 0.02 a0.12 ± 0.03 b0.19 ± 0.04 c
20.837 1382unknown 4nfnfndndnd0.10 ± 0.11
21.1241394.61396.8cis-Jasmone 248sweet, flower0.15 ± 0.010.18 ± 0.030.18 ± 0.04nd
21.7431413.51410.7β-caryophyllen 262–264nf0.45 ± 0.070.43 ± 0.66ndnd
21.7511420.11418(E)-caryophyllene 266–268nfndndnd0.05 ± 0.01 a
22.361453.11451α-humulenenfnfndndnd0.06 ± 0.01 a
22.3611455.91451.6(E)-β-farnesene 271Floralndnd0.01 ± 0.03 and
22.4681468.21463.3(E)-2-dodecenal 93nfndndnd0.05 ± 0.00 a
22.6961472.814721-dodecanol255–259greasendndnd0.07 ± 0.03 a
23.3671480.61478.6Germacrene D 279.7floral0.11 ± 0.02 andndnd
23.3821485.91484trans-β-ionone 239seaweed, violet, flower, raspberrynd0.17 ± 0.17 and0.06 ± 0.01 a
23.4551504.11499.4α-farnesene 260Floral, freshnd0.31 ± 0.23 a0.39 ± 0.03 and
23.471 1502Nerolidol isobutyrate 361.9Sweet, rose-like0.23 ± 0.08 andndnd
23.48215101507Tridecanal132–136nfndndnd0.16 ± 0.02 a
23.731513.11512γ-cadinene272Floral, fresh, sweet0.05 ± 0.06 andndnd
23.91517.81518 cis-jasmin lactone 130sweet, flowernd0.07 ± 0.01 andnd
24.2051523.21520δ-cadinene279nfndnd0.09 ± 0.01 and
24.31115281524trans-calamenene 285–286nf0.21 ± 0.04 andndnd
24.32315291526Naphthalene217.9Tar, camphoric and greasy odornd0.12 ± 0.02 and0.09 ± 0.01 b
24.431 1527.2cis-hexahydro-8a-methyl-1,8(2H,5H)-naphthalenedionenfnfnd0.08 ± 0.020.07 ± 0.00nd
24.63715311532Cis-cadina-1(2),4-diene 137.9nf0.11 ± 0.04 andndnd
24.64415321533.4(E)-γ-bisabolene 262nfnd0.03 ± 0.00 andnd
24.99815351536Dihydroactinidiolide296.1Floral, rose-likendndnd0.11 ± 0.06 a
25.1491533.31537.3α-cadinene271green0.08 ± 0.02 a0.04 ± 0.01 bndnd
25.30815411543E-nerolidol276Slight neroli-like, rose-like and sweet
flavor		0.47 ± 0.14 a1.17 ± 0.10 b1.03 ± 0.18 b0.51 ± 0.08 c
25.3241550.91547Germacrene B287.2nfnd0.11 ± 0.03 andnd
25.6261572.91568(3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene 293.2nf0.52 ± 0.09 and0.13 ± 0.01 b0.20 ± 0.04 c
25.77315621570cis-3-hexanyl n-octanoate292.5nfndnd0.14 ± 0.02 and
25.9281569.51573(Z)-3-hexenyl benzoate 105Green, herb-like0.06 ± 0.080.08 ± 0.010.08 ± 0.000.07 ± 0.01
26.2971581.81580Hexyl benzoate272Wood, green0.07 ± 0.05 a0.11 ± 0.01 a0.13 ± 0.01 b0.14 ± 0.04 b
26.66715881590.1E-2-hexenyl benzoate165–166nfnd0.04 ± 0.00 andnd
27.04816551650Methyl jasmonate302.9Sweent, jasmine-likend1.04 ± 0.74 andnd
27.67616701672cis-3-hexenyl salicylate 145Flower, greennd0.08 ± 0.01 andnd
27.6771676.31673.21-tetradecanol289Wax-likendndnd0.06 ± 0.01 a
28.33716731675α-cadinol137–139Sweet, baking aromandndnd0.05 ± 0.00 a
29.90318271823.1Neophytadiene128nf0.09 ± 0.04 a0.07 ± 0.02 a0.06 ± 0.01 a0.41 ± 0.19 b
31.35918301834Hexadecanal151nfndndnd0.05 ± 0.02 a
32.16218421840Caffeine 178nf0.64 ± 0.07 a0.85 ± 0.20 a0.62 ± 0.39 a0.94 ± 0.20 b
32.98519271931n-hexadecanoic acid methyl ester185nfnd0.09 ± 0.02 a0.05 ± 0.04 and
Total 76.13 ± 11.66 a7.73 ± 0.71 b5.77 ± 0.74 c7.80 ± 1.83 b
nf: not found; nd: not detected; RT: retention time in minutes; RIlit: retention index from literature; RIexp: retention index from this study. The different superscript letters from the same row indicate statistically significant (p < 0.05). Data are expressed as mean ± standard deviation.
Table
Table 2. Aroma contents from tea infusion and odor-activity value (OAV) of green tea, oolong tea, and black tea.
Table 2. Aroma contents from tea infusion and odor-activity value (OAV) of green tea, oolong tea, and black tea.
CompoundThreshold (µg. L−1)Ref.Concentration in Tea Infusion (µg. L−1)OAV
Green TeaOolong TeaBlack TeaGreen TeaOolong TeaBlack Tea
β-cis-ocimene34[24]2.05.11.0<10<1<1
cis-linalool oxide (furanoid)320[25]2.45.38.2<1<1<1
trans-linalool oxide (furanoid) 320[25]2.76.117.2<1<1<1
Linalool 1[24]4.68.921.34.68.921.3
Hotrienol110[26]nd18.9nd<1<1<1
(E)-4,8-dimethylnona-1,3,7-triene nf 2.8ndndnfnfnf
Benzyl nitrile1000[25]3.39.3nd<1<1<1
(Z)-3-hexenyl butanoate 500[24]5.4nd4.4<1<1<1
trans- linalool oxide (pyranoid)0.025[27]ndnd8.2<1<1329.0
Dodecane nf nd4.42.8nfnfnf
Methyl salicylate 40[28]1.5nd9.0<1<1<1
2,6-dimethyl-3,7-octadiene-2,6-diol89 nd5.2nd<1<1<1
Hexyl butanoate607[29]nd3.81.6<1<1<1
4-methylpentyl 2-methylbutanoatenf ndnd2.3nfnfnd
Hexyl 2-methyl butanoatenf ndnd2.2nfnfnf
(E)- geraniol 1.1[30]2.8ndnd2.6<1<1
1,3-bis(1,1-dimethylethyl)benzene81 nd3.9nd<1<1<1
2,5-dihydro-2,5-dimethoxyfuran13[24]nd5.5nd<1<1<1
Indole1[31]14.735.3nd14.735.2<1
cis-3-hexenyl hexanoate16[25]5.1ndnd<1<1<1
trans-2-hexenyl hexanoate781[32]4.79.110.1<1<1<1
Hexyl hexanoate820[32]1.15.63.9<1<1<1
unknown 4nf ndnd2.0nfnfnf
cis-Jasmone 1.9[33]3.78.4nd1.94.4<1
β-caryophyllen 150[24]8.5ndnd<1<1<1
(E)-caryophyllene 64[34]ndnd0.9<1<1<1
α-humulene390[24]ndnd1.2<1<1<1
(E)-β-farnesene 87 nd0.6nd<1<1<1
(E)-2-dodecanal 20[25]ndnd1.1<1<1<1
1-dodecanol0.5[35]ndnd1.4<1<12.7
trans-β-ionone 0.2[25]3.4nd1.116.9<15.7
α-farnesene 0.1[36]6.117.8nd61.0178<1
γ-cadinenenf 1.4ndndnfnfnf
cis-jasmin lactone 2000[37]ndnd3.2<1<1<1
δ-cadinene120[37]nd4.1nd<1<1<1
trans-calamenene nf 2.4nd1.8nfnfnf
Naphthalene300 1.63.1nd<1<1<1
8a-methylhexahydro-1,8(2H,5H)-naphthalenedionenf ndnd2.3nfnfnf
(R)-4,4,7a-trimethyl-5,6,7,7a-tetrahydrobenzofuran-2(4H)-onenf 0.8ndndnfnfnf
α-cadinenenf 0.7ndndnfnfnf
E-nerolidol15[38]2.27ndnd<1<1<1
Germacrene Bnf 23.447.010.2nfnfnf
(3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene nf nd6.04.0nfnfnf
cis-3-hexanyl n-octanoatenf nd6.2ndnfnfnf
(Z)-3-hexenyl benzoate4.5 1.63.61.4<1<1<1
Hexyl benzoatenf 2.26.02.9nfnfnf
E-2-hexenyl benzoatenf ndnd1.2nfnfnf
Methyl jasmonate70[38]ndnd0.9<1<1<1
cis-3-hexenyl salicylate nf 0.9ndndnfnfnf
1-tetradecanol5000[37]20.8ndnd<1<1<1
α-cadinolnf 1.7ndndnfnfnf
Neophytadienenf 1.42.68.3nfnfnf
Hexadecanal75[25]ndnd1.1<1<1<1
Caffeine 29,000[39]17.028.318.8<1<1<1
n-hexadecanoic acid methyl ester1000[25]1.82.3nd<1<1<1
nd: not detected; nf: not found.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Chen, M.; Guo, L.; Zhou, H.; Guo, Y.; Zhang, Y.; Lin, Z.; Sun, M.; Zeng, W.; Wu, H. Absolute Quantitative Volatile Measurement from Fresh Tea Leaves and the Derived Teas Revealed Contributions of Postharvest Synthesis of Endogenous Volatiles for the Aroma Quality of Made Teas. Appl. Sci. 2021, 11, 613. https://doi.org/10.3390/app11020613

AMA Style

Chen M, Guo L, Zhou H, Guo Y, Zhang Y, Lin Z, Sun M, Zeng W, Wu H. Absolute Quantitative Volatile Measurement from Fresh Tea Leaves and the Derived Teas Revealed Contributions of Postharvest Synthesis of Endogenous Volatiles for the Aroma Quality of Made Teas. Applied Sciences. 2021; 11(2):613. https://doi.org/10.3390/app11020613

Chicago/Turabian Style

Chen, Mingjie, Li Guo, Huiwen Zhou, Yaling Guo, Yi Zhang, Zhi Lin, Meng Sun, Wei Zeng, and Hualing Wu. 2021. "Absolute Quantitative Volatile Measurement from Fresh Tea Leaves and the Derived Teas Revealed Contributions of Postharvest Synthesis of Endogenous Volatiles for the Aroma Quality of Made Teas" Applied Sciences 11, no. 2: 613. https://doi.org/10.3390/app11020613

APA Style

Chen, M., Guo, L., Zhou, H., Guo, Y., Zhang, Y., Lin, Z., Sun, M., Zeng, W., & Wu, H. (2021). Absolute Quantitative Volatile Measurement from Fresh Tea Leaves and the Derived Teas Revealed Contributions of Postharvest Synthesis of Endogenous Volatiles for the Aroma Quality of Made Teas. Applied Sciences, 11(2), 613. https://doi.org/10.3390/app11020613

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop