Lifecycle Assessment of Monosodium Glutamate Made from Non-Edible Biomass

Round 1

Reviewer 1 Report

Minor revision of English is needed.

Author Response

RESPONSE TO REVIEWERS

We would like to thank the reviewers for their helpful comments. Our responses to the comments from the editors and reviewers #1 and #2 are given beneath each comment. Where we have changed the text, the corresponding sentences are underlined with page and line numbers in the text.

Response to Reviewer 1:

We appreciate your careful review and valuable comments and suggestions. We have carefully revised the text according to your comments with references to the papers you kindly suggested.

• Minor revision of English is needed.

Thank you for your comments. We have carefully revised the text according to your comments. Our manuscript was revised by English editing service and us, after improving our manuscript by applying reviewer 2 comments.

Reviewer 2 Report

While the authors have improved the paper. I still see that the paper is not ready for publication. Here are my specific comments:

• The contribution and main purpose of the study still not clear.
• The authors need to look at the organization of their paper. The main sections of LCA usually used are not presented clearly: goal and scope definition, inventory analysis, impact assessment, interpretation. Dividing the paper in this way would help the readers to understand the content and the flow of the paper. The titles of sections as they are now are confusing. Is the discussion only one small section? "3.5"?
• The authors need to re-visit the grammar and writing of the paper. There are mistakes and grammatical issues that impact the understanding in some parts.
• The conclusions section need to be expanded and further developed. 

Author Response

RESPONSE TO REVIEWERS

We would like to thank the reviewers for their helpful comments. Our responses to the comments from the editors and reviewers #1 and #2 are given beneath each comment. Where we have changed the text, the corresponding sentences are underlined with page and line numbers in the text.

Response to Reviewer #2

We appreciate your careful review and valuable comments and suggestions. We have carefully revised the text according to your comments with references to the papers you kindly suggested.

• The contribution and main purpose of the study still not clear.
  
  

We revised the end paragraph (55~62) of "1. Introduction", which added the goal of this study and restructured paragraph. Hence, same meaning sentence on "2. Materials and Methods" was deleted.

• The authors need to look at the organization of their paper. The main sections of LCA usually used are not presented clearly: goal and scope definition, inventory analysis, impact assessment, interpretation. Dividing the paper in this way would help the readers to understand the content and the flow of the paper. The titles of sections as they are now are confusing. Is the discussion only one small section? "3.5"?

We restructured our manuscript as follow.

Goal: added to the end paragraph (60~62) of "1. Introduction"

Scope definition: restructured first half (64~88, 97~99) of "2. Materials and Methods"

Inventory analysis: kept the middle (103~106) of "2.  Materials and Methods"

Interpretation: kept "3. Results and discussion"

The 3.5 title was changed to "Breakdown of main raw material stage", since there are the discussion contents in 3.1 ~3.5.

• The authors need to re-visit the grammar and writing of the paper. There are mistakes and grammatical issues that impact the understanding in some parts.

Our manuscript was revised by English editing service and us, after improving our manuscript by applying your comments.

• The conclusions section need to be expanded and further developed. 

We added the limitation contents to the end (369~380) of '4. Conclusion".

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have adequately addressed the comments and improved the paper to serve the purpose of the work.

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.

Round 1

Reviewer 1 Report

Reviewer comments.

This manuscript reports the environmental assessment of monosodium glutamate production obtained from the non-edible biomass throughout fermentation of pulverising biomass,  and then, glycosylating of the substrate. The analysis is compared environmentally with the production of MSG using the traditional tapioca starch processes.  Assessment is of good quality, as it shows by the discussion of the results. Furthermore, the manuscript gives a precise evaluation of the performance of the variations in carbon footprint, water scarcity and air pollution footprints. Consequently, I have significant recommendations for the authors:

• In the abstract, line 21, the authors should introduce the secondary factor and the inventory that they use

• In the introduction, line 42, it could given more details about the works cited (e.g. the kind of biomass analyse)

• At the end of the introduction, it said that there are not cycle life assessment for the production of MSG from non-edible biomass. However, there are more life cycle assessment of MSG that is produced by other biomass (such as https://doi.org/10.1016/j.jclepro.2020.122126), and I consider that you should include a small review of cycle life assessment for the production of MSG to compare your result

• In the methodology, Could you clarify Table 1? it is a little bit confusing

• In section 2.4, could you explain the reason for selecting nine factors?

• In line 169-171, could you re-write this sentence? It isn't easy to understand

• In figure 5 and 6, the labels are missing.

• In line 185, it is asses GHG emissions during ethanol production. Is this for both biomass, tapioca starch and non-edible biomass? Why there is no difference between both process?

• In figure 7, the number cannot be seen

• In line 254, could you discuss why the reduction of water scarcity footprint on non-edible biomass? I am not convinced if it is right not to allocate the water shortage footprint because the non-edible biomass has little commercial value.

• The carbon footprint could have an impact on human health in the long term. There should be a way to evaluate that.

• Several grammatical errors/typos can be found throughout the manuscript. There are sentences that the verb, adjective, conjunction are missing that makes the document difficult to understand. It should be carefully revised at this point.

• There is also format mistake in the unit such as "kilo tons/y" and figures, tables. It should be adequately reviewed.

Reviewer 2 Report

The manuscript Lifecycle assessment of monosodium glutamate  made  from non-edible biomass by Keiji NAKAMURA and coworkers focuses on a timely topic of relevance from environmental point of view. Essentially, this study assessed monosodium glutamate (MSG) produced by fermenting pulverized and glycosylated non-edible biomass and compared the assessment of MSG produced by the fermentation of glycogen as a conventional process. Practically, this study compared the carbon, water, and air pollution footprints. Although the results are of interest for the readers, before publication the text should be thoroughly revised in the main sections as follows: .

• The results should be more concisely presented and without repetitions (e.g. see: the water scarcity footprint several times on Pages 9-10)
• Discussions should be elaborated in a more detailed manner, mainly in the context of the relevant knowledge from the literature and the impact of results on the environment.
• Conclusions should be better correlated with the results and presented in a separate section
• References 4, 5, 15 and 16 should be updated according to the journal style

Reviewer 3 Report

The paper is poorly written and structured, which is impacting the understanding of the significance of the topic and the clarity of the article. Here are some specific comments:

• The whole paper needs to be very well checked again for grammatical mistakes and non-clear sentences. In some parts, the idea is not clear and re-writing is needed.
• The LCA phases need to be followed. What is the functional unit? How has the functional unit been established? How is the useful life established? 
  Why did you choose the databases used? Why did you choose your impact analysis methodology? You must justify your chosen impact categories?
  It is necessary to develop the study based on the phases of the ISO 14040 and ISO 14042 standards. Even there is no reference and no introduction for the well known LCA method and its phases in introduction. The methodology needs to be much more explained and justified in an organized way.
• Results: The results are very poor, the graphs are very basic and although there are interesting comparisons, they are not explained as required by the standard.
• Discussion: It should be improved considerably. It is very poor and too short as it stands now and does not reflect any significance of the study
• Need to include a conclusion part. 
• Improvement in the number of references is needed covering probably what previous similar studies have done and what you are proposing here (in introduction).