Analysis of Aroma Volatiles from Michelia crassipes Flower and Its Changes in Different Flower Organs during Flowering

Round 1

Reviewer 1 Report

The manuscript presented by the authors is interesting and has data relevant to the chemistry of Michelia aromas. However, I have a few notes to make:

1) In the abstract they should describe the meaning of the acronym OAV.

 

2) If the work in question involves the study of flower organs, the phrase "This contributes to the complex fruity, woody and floral 17 aromas of M. crassipes", does not make sense.

 

3) The authors did not include who the taxonomist was, and exsicata number of the collected plant material.

 

4) Was the extraction performed on the same day as the collection of the material?

 

5) The authors mention that they collected material from 10 different individuals, however in the Table it appears to be from a single individual.

 

6) It would be interesting to include in the table which compounds are benzenoids.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have performed the HS–SPME-GC-Orbitrap-HRMS to identify the scent compounds emitted from different parts of the M. crassipes flower at different flowering stages. The manuscript is well written. Some minor comments are:

Please correct names of the compounds

• correct the size of letters for the relative configuration for example D-limonene (correct throughout the manuscript)
• trans, cis should be italic (correct throughout the manuscript)
• α, β should be italic

line 143 Define TO

line 154 What descriptions? Also rephrase “chemical categories”

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript entitled "Comparative analysis of aroma volatiles of different flower organs of Michelia crassipes at different flowering stages" is about the chemical composition of volatiles from different flower organs at different stages of the above mentioned species. Authors performed an untargeted metabolomic analysis using gas chromatography coupled to a high resolution mass spectrometer to identify the chemical compounds and determined the odor activity value. In addition, authors performed a microscopical analysis to study the oil cells. The experiments are well conducted and the manuscript is well written. I enjoyed reading it. 

My major comments are:

1.- Authors claim the use of high resolution mass spectrometry to identify the volatiles compounds. However it is missing a table which describes mass spectrometric features used for identification, for example: m/z value, error in ppm, % of similarity, ions used for identification, etc. This information is important because validate your identification.

2.- Did authors corroborate the identity of authentic standards? Otherwise, all compounds identification are tentative.

3.- In Figure 4, that about density (right figure), the statistical analysis should be revised. The error bars are so high that makes difficult to believe that there are statistical differences.

 

All minor comments are in the attached file. Most of them are missing information like mass spectrometer ion source (EI, CI) or abbreviature explanations and a few misspellings. 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

 

- The title of the manuscript is not supported by the content of the text. Chemical composition is presented, however no in-depth discussion or comparison of the composition of the volatile phase of the parts of the flower studied according to the stage of flowering are presented.

- The headspace solid-phase microextraction (HS–SPME) is not generally able to determine the total composition of the head space: it is an analytical extraction technique depending on the affinity of the components of the volatile phase with respect to the fiber used. Thus, the composition and the percentages of the various constituents of the mixture analyzed can be different with the real composition of the volatile phase emitted by the flowers studied: only the compounds having an affinity with respect to the fiber used have been characterized. It would therefore be more convenient to compare the composition of the volatiles from the different flower organs studied with that of their essential oil, and the HS-SPME of these different essential oils.

- The manuscript should be checked by a native English speaker.

- The introduction is too long: it must be concise and succinct.

-Further study on the volatiles of the different flower organs will be of great importance. Indeed, the comparison of the results obtained with those of the analysis of the essential oils extracted by hydrodistillation from the different organs of the flowers will be of great importance.

- Page 3 ligne 112 : Authors stated  that «The absorbed volatiles was analyzed using GC-HRMS,…. » : in the HS–SPME the volatile compounds are adsorbed  (not absorbed) by the fibre.

- page 4 : 2.5. Paraffin section detection : it is important to add the reference of the procedure used in this part.

-Page 9 : discussion, lines 256-262, Authors stated  that « The chemical composition of M. crassipes floral volatiles has also been reported. However, only three aroma constituents were identified using the MeOH extraction method and nuclear magnetic resonance (NMR) ……….. Our results showed that the main compounds of M. crassipes flower are terpenes, including 48 compounds representing total relative content of up to 84%. α-Guaiene, β-caryophyllene and germacrene B belonging to terpenes had the highest relative contents » : The authors attributed the difference in composition observed to the performance of the technique they used: the authors must take into account that HS-SPME depends on the affinity and the vapor pressures of the compounds adsorbed on the fiber used.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

The current format is souhaitable for publication

Author Response

Thank you for your comments!