Quantitatively Unravelling the Impact of High Altitude on Oolong Tea Flavor from Camellia sinensis Grown on the Plateaus of Tibet
Round 1
Reviewer 1 Report
Dear authrs, please clarify the experimental plan. In particular, enter an accurate description of the sampling. Which and How many samples were considered? the analyzes were made a double in triple, how many replicates? (for TOT and OOT). kindly specify this information also in the descriptions of the tables (results). I believe this information is necessary.
Line 81: please replace "two" with "2"
line 120: please replace "fifty" with "50"
line 140: please replace "thirty" with "30"
line 144: please replace "ten" with "10"
Line 203 to 206: please rewrite the sentence. it is not clear
Author Response
Which and How many samples were considered? the analyzes were made a double in triple, how many replicates? (for TOT and OOT). kindly specify this information also in the descriptions of the tables (results). The analyzes were made a double in triple, how many replicates? (for TOT and OOT).
R1: Thank you for your comments. All the analyzes of TOT and OOT were performed in triplicate. We have added a description of the number of repetitions of experimental operations in the materials and methods section and also in the descriptions of the results (Line 110, 138, 152, 165, 188, 293, 354).
Line 81: please replace "two" with "2"
line 120: please replace "fifty" with "50"
line 140: please replace "thirty" with "30"
line 144: please replace "ten" with "10"
R2: Thank you for your comments, changes have been made as instructed (Line 81, 134, 156, 160).
Line 203 to 206: please rewrite the sentence. it is not clear.
R3: Thank you for your comments. We have revised the sentence (Line 236-239).
Reviewer 2 Report
Manuscript horiculturae-1756316 presents and iteresting work regarding the posiibility of change in the quality (form chemical, and sensorical points of view) of oolong tea, produced with C. sinensis cultivated in different places. The experiment design is well prepared. Nevertheless, Authors have to improve the desciption of used analytical methods and clarify some of the presented results. All my concerns are given as coments in pdf files.
Moreover, I please clarify if C.sinensis is native for Tybet? If not, please discuss the endangerment of introducing the plant into its unnatural ecosystem.
Comments for author File: Comments.zip
Author Response
I please clarify if C.sinensis is native for Tibet? If not, please discuss the endangerment of introducing the plant into its unnatural ecosystem.
R1: Thank you very much for your comments. Tea plants are thought to be originated from the southwestern China including Yunnan and the adjacent provinces (Ref1: The origin of tea plant. in Proceedings of 2001 International Conference on O–Cha (Tea) Culture and Science (Session II); Ref2: Draft genome sequence of Camellia sinensis var.sinensis provides insights into the evolution of the tea genome and tea quality). Maybe C.sinensis is not a native for Tibet, and it was first introduced to Tibet in 1956 (Ref: Discussion on the Development Situation and Countermeasures of Tea Industry in Tibet). However, the endangerment into unnatural ecosystem have not been evaluated scientifically.
I suggest to provide actual amount of added IS (ug), instead its volume and concentration.
R2: Thank you for your comments. We have provided actual amount of added IS (Line 93).
What about conditioning of the sample at demanded temperature? If Authors introduced the SPME fiber right after placing the sample into HS-vial, there was no time for reaching the equilibrium state between the sample and headspace. Please clarify,
R3: Thank you for your comments, we have described clearly in the manuscript (Line 94).
set font to italic
R4: Thank you for your comments. We have set the font to italic (Line 113, 255, 258, 259, 265, 361, Table 2).
In subsection Plant materials and reagents Authors stated that they purchased C8-C40 n-alkanes mix. Please clarify.
R5: Thank you for your comments. A HP-5MS column (30 m × 0.25 mm × 0.25 µm film thickness) was used in our experiments, and under our setup parameter, only C9 to C23 be detected sequentially.
Regarding the analytical standards, the assumed values of RI and mass spectra match are pretty high. Normally the 10-15 points RI difference is acceptable, while for mass spectra at least 90%.
R6: Thank you for your comments, we have modified the assumed values of RI and mass spectra match (Line 119).
In Quantification of caffeine contents, what was the quantification method?
R7: Thank you for your comments. Caffeine contents were quantified by comparison of its retention time and absorption spectrum with those of the standard. We have added more details about the quantification of caffeine contents (Line 163-164).
In Quantification of catechin contents, what was the quantification method?
R8: Thank you for your comments. The contents of C, EC, EGC, ECG and EGCG were quantified by comparison of their retention time and absorption spectrum with those of standards. We have added more details about the quantification of catechin contents (Line 186-188).
In statistical analysis, why italic?
R9: Thank you for your comments. We have changed the font to non-italic (Line 191-195).
Please add the labels with percentage of particular chemical classes into the graphs.
R10: Thank you for your comments. We have added the labels with percentage of particular chemical classes into the graphs (Supplemental Figure 2).
Please introduce into Materials and methods section, the description of Wickremasinghe-Yamanishi ratio calculation. Provide the description of Owour’s
flavor index into M&M section.
R11: Thank you for your comments. Calculation of Wickremasinghe-Yamanishi ratio and Owuor’s flavor index have been descripted in Materials and methods section (Line 120-129).
Please add units to the graphs
R12: Thank you for your comments. We used the relative content of aroma compounds without units.
It is impossible to identify D-limonene by HP-5MS column, since it is not applicable for enantiomeric analysis.
R13: Thank you for your comments. We have been double checked the search report of Nist 11 database carefully. In all samples, the results of this substance searched in Nist 11 database are all D-limonene, and the matching degree is greater than 95%.
It is impossible to identify (+)-γ-Cadinene by HP-5MS column, since it is not applicable for enantiomeric analysis.
R14: Thank you for your comments. After carefully checking the samples’ search reports of Nist 11 database, we have corrected (+)-γ-Cadinene to γ-Cadinene (Table 2).
Please use consist type of description for trans (E) and cis (Z).
R15: Thank you for your comments. We have used consist type of description for trans (E) and cis (Z), and we change trans to E, as well as change cis to Z (Table 2, Supplemental Table 1, Supplemental Table 2).
Reviewer 3 Report
In this work, entitled Quantitatively unravelling the impact of high altitude on oolong tea flavor from Camellia sinensis grown on the plateaus of Tibet, Peifen Chen and coworkers describe the impact of high altitude on the oolong tea flavor, derived from Camellia sinensis grown on the plateau of Tibet.
The volatile components in TOT and OOT showed a slight difference, and principal component analysis revealed that the characteristic aroma substances distinguishing tea grown in Tibet from tea grown in Guangdong were hotrienol and benzyl alcohol.
This work can be considered for publication in Horticulturae after improving certain aspects of the manuscript.
Page 1 row 42-44, sentence:
To meet the amplified demand of oolong tea, more and more varieties suitable for the manufacture of oolong tea have been introduced to other regions of China.
should be reformulated; instead of should write for
Page 2, Table 1, entry 5, the W5C sensor type, Short chain alkane aromatics, it is not clear for aromatic compounds with short-chain or….
Also in this table, entry 6, Selectivity for Methyl?????
Page 3 row 102: The heating program had an initial temperature of 50 ℃ for 1 min, was increased to 220 oC for 5 min at the rate of 5 oC /min, and was followed by a solvent delay time of 4 min. The detector had an electron impact (EI) ionization source maintained at 230 °C and operated at 70 eV. This sentence should be reformulated.
Page 3 row 132, 2% ninhydrin, should be mentioned in parenthesis what kind of solvent was used.
Page 4 row 150, space should be deleted.
In the case of quantification of caffein, catechin should be introduced in supplementary data in a table with calculated quantities. a more detailed explanation of these analyses should be introduced in the Results and Discussion part.
Page 5 line 211 sentence must be reformulated: The Owuor’s flavor index of TOT and OOT were 39.67 and 29.06, respectively, which implied that the aroma of TOT was significantly better than that of OOT.
What do the digits in superscript in table 2 in the Aroma description column represent?
Please correct the errors mentioned above.
Author Response
Page 1 row 42-44, sentence:
To meet the amplified demand of oolong tea, more and more varieties suitable for the manufacture of oolong tea have been introduced to other regions of China.
should be reformulated; instead of should write for
R1: Thank you very much for your comments. We have changed “of” to “for” in line 44.
Page 2, Table 1, entry 5, the W5C sensor type, Short chain alkane aromatics, it is not clear for aromatic compounds with short-chain or….
R2: Thank you for your comments. The W5C sensor type, it means short chain alkane and aromatics compounds. We have corrected the description to be more accurate (Table 1, entry 5).
Also in this table, entry 6, Selectivity for Methyl?????
R3: Thank you for your comments. We have changed “Methyl” to “Methane” in entry 5, Table 1.
Page 3 row 102: The heating program had an initial temperature of 50 ℃ for 1 min, was increased to 220 oC for 5 min at the rate of 5 oC /min, and was followed by a solvent delay time of 4 min. The detector had an electron impact (EI) ionization source maintained at 230 °C and operated at 70 eV. This sentence should be reformulated.
R4: Thank you for your comments. We have clarified the description of experimental conditions (Line 103-106).
Page 3 row 132, 2% ninhydrin, should be mentioned in parenthesis what kind of solvent was used.
R5: Thank you for your comments. The 2% ninhydrin solution was diluted in ultrapure water with 0.8mg/mL stannous chloride. We have added specific descriptions of solvents in the materials and methods section (Line 146).
Page 4 row 150, space should be deleted.
R6: Thank you for your comments. We have deleted the space.
In the case of quantification of caffein, catechin should be introduced in supplementary data in a table with calculated quantities. A more detailed explanation of these analyses should be introduced in the Results and Discussion part.
R7: Thank you for your comments. We have added the original data of caffein, catechin contents in Supplemental Table 3. A more detailed explanation had been added in the Results and Discussion part (Line 336).
Page 5 line 211 sentence must be reformulated: The Owuor’s flavor index of TOT and OOT were 39.67 and 29.06, respectively, which implied that the aroma of TOT was significantly better than that of OOT.
R8: Thank you for your comments, the sentence have be reformulated (Line236-239).
What do the digits in superscript in table 2 in the Aroma description column represent?
R9: Thank you for your comments. The different digits in superscript in table 2 means the compounds found in different dates, in which ‘1’ means the compounds found in references [29], ‘2’ found in the Flavornet database (https://www.flavornet.org/flavornet.html), ‘3’ found in femaflavor (https://www.femaflavor.org/flavor-library), ‘4’ means the compounds found in references [39]. We have clarified this sentence (Line295-298).
Reviewer 4 Report
The current manuscript is an original research article that repots on the flavour compounds and aroma developemnt of tea from the high altitude of Tibet. The article is novel in nature given the limited data in the scientific literature about tea from Tibet. The authors determined volatile compounds and used statistical analysis to differentiate tea samples from Tibet with those of other origin.
The manuscript is well designed and written. The English language is good and the conclusions drawn from the results are convincing. There are , however, some points that authors should better discuss and revise. I have indicated them within the attached pdf. Based on these comments, I suggest a minor revision prior to further consideration for publication.
Comments for author File: 
Comments.pdf
Author Response
Change substances to compounds
R1: Thank you very much for your comments. We have changed substances to compounds (Line 18, 199, 215).
There is no need for italics here.
R2: Thank you for your comments. We did the formatting to change the font to non-italic (Line 191-195).
Change aromatic substances to volatile compounds
R3: Thank you for your comments. We have changed aromatic substances to volatile compounds (Line 250).
Data must be compared with those of different herbal teas. The recent study ''European Food Research and Technology, 247, 961–974 (2021)'' must be introduced for better comparison of the data with herbal teas from the European zone.
R4: Thank you for your comments, but we don’t think it would available to compared our data with those of different herbal teas, the recent study ''European Food Research and Technology, 247, 961–974 (2021)', since Oolong tea is not one kind of herbal tea. The ingredient of Oolong tea is only the leaves of tea plant (Camellia sinensis) without others. Green, black and oolong are determined by the employed processing technologies and Oolong tea sets it apart from green and black teas (Ref: Chinese oolong tea: An aromatic beverage produced under multiple stresses). We hope you could understand.
Change revealed to showed
R5: Thank you for your comments. We change revealed to showed (Line 312).
Round 2
Reviewer 1 Report
Thanks for your kind replies
I only suggest checking line 82 (2g)
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
