Revealing the Changes in Compounds When Producing Strong-Flavor Daqu by Statistical and Instrumental Analysis
Round 1
Reviewer 1 Report
Dear authors and editors, I have some comments that should be done to improve your manuscript before considering it for publication in the fermentation journal. More the writing style needs to be improved more and more. There are many of information that needs to be added to the manuscript. I suggested major revisions.
The title should be revised and deleted metabolomics from the title. The paper focuses on flavor. Please check and revise the title.
I would the authors to modify and follow this structure in the abstract; background and problem, the rationale for the study; research objectives; some methodology; important data including statistical analysis; conclusions, novelty, and the importance of the findings.
I would the authors to add more with deep meaning.
Please add one paragraph more in the introduction explaining the methods used for analyzing the volatile compounds. Why the authors selected this method (GC-MS-HS-SPME)?
Please re-write the aim of your work clearly at the end of the introduction with more details and how it is good for a food science major regarding food processing.
In the chemicals section, please mention all the chemicals and solvents you used in more detail and follow the journal format to write the chemical information.
In the sample collection section, the authors should mention more information about the fermentation condition.
For the RI, the authors should explain the methods, how they prepare the RI solution, inject it in the GC-MS, and how they calculated it for the identified volatile compounds.
For volatile compounds identification and determination, there are more details the authors should add? Please check this article, DOI10.1007/s42770-022-00773-7
The results and discussion are so weak, need more explanation with other research papers. The style of writing is so poor.
In figures 1, 2, 3 and 4 the authors should add the meaning of the A, B, C, D, E and F in the figure caption.
For Table 1, the authors should add RI, CAS no, Molecule formula, Odor description, and ID for each identified compound.
Also in Table 1, the authors should make a statical analysis between the samples.
Acronym/abbreviation should be defined the first time (and only one time) they appear in each of three sections: the abstract; the main text; the first figure or table (when defined for the first time, the acronym/abbreviation should be added in parentheses); then use acronyms.
I would the authors to try to make the discussion in deep with the previous studies
For the format of the reference, the authors need to check
Author Response
- The title should be revised and deleted metabolomics from the title. The paper focuses on flavor. Please check and revise the title.
Author reply: Thanks for your suggestions. The title has been revised.
- I would the authors to modify and follow this structure in the abstract; background and problem, the rationale for the study; research objectives; some methodology; important data including statistical analysis; conclusions, novelty, and the importance of the findings.I would the authors to add more with deep meaning.
Author reply: Thanks for your thorough review and valuable suggestion. The abstract has been revised as suggested, and the meaning has been further explored. The changes have been marked in red.
- Please add one paragraph more in the introduction explaining the methods used for analyzing the volatile compounds. Why the authors selected this method (GC-MS-HS-SPME)?
Author reply: Thanks for your suggestions. The method for analyzing volatile compounds has been added in the introductory section of the revised manuscript and was marked in red.
The GC-MS-HS-SPME was chosen because GC-MS is one of the most powerful tools for the separation and detection of complex compounds due to the extreme separation power of GC and the unique ability of MS to identify unknown compounds with great sensitivity. HS-SPME is a simple, low cost and environmentally friendly technique for the extraction of volatile components from solid samples compared to other pre-treatment methods. The GC-MS-HS-SPME was selected through literature research, considering that this study will eventually be applied in practice and requires the pretreatment method to be as simple, fast and accurate as possible.
- Please re-write the aim of your work clearly at the end of the introduction with more details and how it is good for a food science major regarding food processing.
Author reply: Thanks for your suggestions. The purpose of the study at the end of the introduction has been rewritten and its important contribution to the development of baijiu has been described and marked in red.
- In the chemicals section, please mention all the chemicals and solvents you used in more detail and follow the journal format to write the chemical information.
Author reply: Thank you. Chemicals and solvents used in this study have been supplemented in the chemicals section as required and marked in red.
- In the sample collection section, the authors should mention more information about the fermentation condition.
Author reply: Thanks for your suggestions. The relevant fermentation status has been supplemented and marked in red.
- For the RI, the authors should explain the methods, how they prepare the RI solution, inject it in the GC-MS, and how they calculated it for the identified volatile compounds.
Author reply: Thank you. Relevant method information, solution preparation information and sample injection information have been added to GC-MS information and marked in red.
- For volatile compounds identification and determination, there are more details the authors should add? Please check this article, DOI10.1007/s42770-022-00773-7
Author reply: Thanks for your suggestions. The relevant details have been supplemented and marked in red.
- The results and discussion are so weak, need more explanation with other research papers. The style of writing is so poor.
Author reply: Thank you for your advice. A comparative analysis of the results and discussion of this study with other papers has been added and marked in red.
- In figures 1, 2, 3 and 4 the authors should add the meaning of the A, B, C, D, E and F in the figure caption.
Author reply: Thank you. The meanings of A, B, C, D, E, F have been added to the figure caption.
- For Table 1, the authors should add RI, CAS no, Molecule formula, Odor description, and ID for each identified compound.
Author reply: Thanks for your suggestions. The above information has been supplemented in Table 1 and marked in red.
- Also in Table 1, the authors should make a statical analysis between the samples.
Author reply: Thank you for your advice. The statical analysis between the samples has been supplemented in Table 1 and marked in red.
- Acronym/abbreviation should be defined the first time (and only one time) they appear in each of three sections: the abstract; the main text; the first figure or table (when defined for the first time, the acronym/abbreviation should be added in parentheses); then use acronyms.
Author reply: Thanks for your suggestions. The relevant content has been modified and marked in red.
- I would the authors to try to make the discussion in deep with the previous studies.
Author reply: Thank you. The related discussion has been added and marked in red.
- For the format of the reference, the authors need to check.
Author reply: Thanks for your suggestions. The format of the references has been confirmed and revised and marked in red.
Reviewer 2 Report
In this manuscript, HS-SPME-GC-MS was used to investigate the change trend of volatile metabolic components during the process of MTD, and the result was in favor of revealing the characteristics of the process. However, the following issues need to be further clarified or improved.
1) This technology is usually used to qualitatively or semi- quantitatively characterize the volatile components
2) Can represent the main characteristics of the changes in the koji making process for sampling time point?
3) The changes of metabolic components are mainly caused by biotic and abiotic factors. The correlation between volatile metabolic components and these factors is uncertain. What is the scientific significance?
4) The English expression of this manuscript needs to be greatly revised, especially the professional terms should be consistent.
5) Some obvious mistakes in the manuscript have been marked by green.
Comments for author File: 
Comments.pdf
Author Response
1) This technology is usually used to qualitatively or semi- quantitatively characterize the volatile components.
Author reply: Thanks for your thorough review. The sample in this study is solid Daqu, and HS-SPME-GC-MS is selected for research through the investigation of relevant literature. At the same time, the focus of this study is to explore the changes laws of volatile compounds in the maturing process of Daqu, rather than the quantitative recombination experiment of a sample. Based on the above considerations, this study finally selected HS-SPME-GC-MS for qualitative and semi-quantitative analysis.
2) Can represent the main characteristics of the changes in the koji making process for sampling time point?
Author reply: Thanks for your question. The sampling time of daqu in this study is an important stage in the production process. A, B, C, D, E and F respectively represent the “Rufang”, “Yifan”, “Erfan”, “Sanfan”, “Hefang” and “Chufang” of the production process, which can represent the main characteristic change in the process of maturation. In addition, the production of Daqu uses the same grain raw materials, fixed raw material ratio, the same production technology, and in a fixed Qu room with relatively stable conditions. Therefore, even with different batches, the same type of daqu still maintains a relatively stable flavor variation rule, so the samples selected in this study are representative.
3) The changes of metabolic components are mainly caused by biotic and abiotic factors. The correlation between volatile metabolic components and these factors is uncertain. What is the scientific significance?
Author reply: Thanks for your question. Daqu sample selected in this study has a relatively complete and mature production process, and its selected raw materials, ratio and production environment are also under strict control. Therefore, exploring the variation rule of volatile compounds can promote the combination of baijiu production tradition and science, realize the accurate and rapid monitoring of daqu maturity level, and further improve the quality stability of daqu and baijiu. In addition, it is beneficial to promote the development process of baijiu mechanized production to clarify the change rule of the index compounds in detail.
4) The English expression of this manuscript needs to be greatly revised, especially the professional terms should be consistent.
Author reply: Thank you for your comments, The manuscript has been revised by native English speakers.
5) Some obvious mistakes in the manuscript have been marked by green.
Author reply: Thanks for your thorough review and valuable suggestion. These mistakes have been corrected and are marked in red.
Round 2
Reviewer 1 Report
The paper can be accepted.
Reviewer 2 Report
The revised manuscript conforms to the published standard
