Viscosity Analysis of Electron-Beam Degraded Gellan in Dilute Aqueous Solution

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The presented work is devoted to the study of structural and conformational changes of gellan gum in dilute solution under the action of an electron beam, affecting its rheological and functional properties. The obtained results may be important when using gellan gum in food products, in drugs subjected to radiation sterilization, or for obtaining a polymer with a given molecular weight by radiation degradation. However, the work requires major revision. Specific suggestions and comments for the authors are presented below.

1. The introduction contains a lot of well-known theoretical information about the parameters characterizing the behavior of polymers in solution. It should be made clearer in terms of how your study advances work in this area. Thus, the purpose of this study will look justified. Here, it is necessary to briefly describe the previously obtained data on how irradiation conditions affect gellan gum.
2. What is the rationale for the chosen dose range? The doses used are much lower than those used in radiation sterilization of food or drugs.
3. In Section 2.4, the absorbed dose rate should be indicated.
4. In Figure 2, the equation of the straight line approximating the obtained data should be given. And also R² (the determination coefficient) should be given.
5. The title of the Results and Discussion section in this version does not reflect its contents. The text contains only a brief description of the results, but no assumptions or discussion to explain them are presented. For example, how does the irradiation atmosphere affect gellan gum? Are intramolecular cross-linking processes possible?
6. What are large (L), medium (M), and small (S) molar masses of gellan gum?
7. Finally, 16 of the 26 references were published 20 or more years ago. Thus, the current state of the art is not reflected.
8. In Figures 1 and 2, the ordinate axis labels are shifted

 

9. In Figures 7 and 8, the legend is not displayed.

 

10. Review your conclusions. They should contain specific results of your research work.

Author Response

Response Letter 1 to the First Reviewer Report

ID: Physchem-3825138 September 1, 2025

We sincerely thank you for your careful reading of our manuscript and for the constructive comments and suggestions. We have carefully revised the manuscript according to these recommendations. Below, we provide a point-by-point response to each comment, indicating the changes made.

 

Reviewer’s Comment 1

The introduction contains a lot of well-known theoretical information about the parameters characterizing the behavior of polymers in solution. It should be made clearer in terms of how your study advances work in this area. Thus, the purpose of this study will look justified. Here, it is necessary to briefly describe the previously obtained data on how irradiation conditions affect gellan gum.

Response

We thank the reviewer for this valuable comment. The Introduction has been revised to highlight the novelty of our work and to justify its contribution compared with existing studies. In particular, we have included a short overview of previous reports on how irradiation affects gellan gum and clarified how our work advances the understanding of structural and conformational changes under electron-beam treatment (see revised Introduction)

Reviewer’s Comment 2

What is the rationale for the chosen dose range? The doses used are much lower than those used in radiation sterilization of food or drugs.

Response

We appreciate this observation. The rationale for the selected dose range has been clarified in Section 2.3. Our study focused on structural and conformational modifications of gellan gum rather than sterilization, which requires higher doses. The lower dose range was intentionally selected to avoid extensive chain scission and to better observe gradual molecular changes relevant for tailoring physicochemical properties.

Reviewer’s Comment 3

In Section 2.4, the absorbed dose rate should be indicated.

Response

 

We have added the absorbed dose rate in Section 2.3. The value is now reported as 2.5 kGy/min

Reviewer’s Comment 4

In Figure 2, the equation of the straight line approximating the obtained data should be given. And also R² (the determination coefficient) should be given.

Response

As suggested, the regression equation and R² value have been added to Figure 2. The caption has also been updated accordingly.

Reviewer’s Comment 5

The title of the Results and Discussion section in this version does not reflect its contents. The text contains only a brief description of the results, but no assumptions or discussion to explain them are presented. For example, how does the irradiation atmosphere affect gellan gum? Are intramolecular cross-linking processes possible?

Response

We agree with the reviewer and have substantially revised the Results and Discussion section. The revised text now includes interpretations of the observed trends, discussing possible mechanisms such as chain scission versus intramolecular cross-linking and the role of the irradiation atmosphere. This provides a more complete discussion beyond simple description of the results (see Section 3).

Reviewer’s Comment 6

What are large (L), medium (M), and small (S) molar masses of gellan gum?

Response: We have clarified the definitions of HM (instant if L),MM (instant if M), and SM (instant if M) molar mass fractions in Section 3.2. The ranges are now explicitly indicated in the manuscript (HM = 60.59 kg/mol, MM = 47.81 kg/mol, SM = 39.81 kg/mol).

Reviewer’s Comment 7

Finally, 16 of the 26 references were published 20 or more years ago. Thus, the current state of the art is not reflected.

Response

We thank the reviewer for this important comment. The reference list has been updated with more recent literature (2014–2025) related to electron-beam degradation

 

of polysaccharides, gellan gum behavior, and polymer scaling laws. This better reflects the current state of the art

Reviewer’s Comment 8

In Figures 1 and 2, the ordinate axis labels are shifted.

Response

The formatting of Figures 1 and 2 has been corrected. The axis labels now appear properly aligned.

Reviewer’s Comment 9

In Figures 7 and 8, the legend is not displayed.

Response

Legends have been added to Figures 7 and 8, clearly indicating high molar mass (HM), medium molar mass (MM), and small molar mass (SM) fractions.

Reviewer’s Comment 10

Review your conclusions. They should contain specific results of your research work. Response:

The Conclusions section has been revised to include specific numerical results, including the molar mass degradation lifetime (67.90 kGy), scaling coefficients (a = 0.95, ? = 0.65,

?_A2 = 0.089), and changes in flexibility parameters. This ensures the conclusions accurately summarize the main outcomes of the study (see revised Conclusions).

 

Sincerely yours

Nada Elzawi (On behalf of the authors) nada.elzawi@uob.edu.ly

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study explored the effect of E-beam radiation on gellan conformations in dilute aqueous solutions. It provided a reference basis for the structural and conformational changes of colloid under electron beam radiation. However, this work research is too simplistic and requires major revisions to enrich it.

1. In the abstract, the author needs to demonstrate why this research is being conducted, as well as the urgency and necessity of this work.
2. The first five paragraphs of the introduction are mostly about popularizing knowledge of polymer physics. However, the introduction did not provide a good elaboration on issues such as why this research was conducted, the current status of this research, and the innovative points of this research.
3. 2.3 and 2.5 belong to the test content and should be transferred to the characterization of 2.6.
4. All the pictures related to the results in the figure lack scales and need to be improved.
5. In Figures 1 to 6, there is only one influence of radiation on the gellan  performance, which is unscientific. Moreover, the content is only limited to describing the result and does not provide an in-depth explanation of the reasons for the result.
6. The conclusion section should not be presented in a bullet-point format but should be modified to a paragraph format.
7. The cited literature is too outdated to reflect the prospective nature of this research.

Author Response

Response Letter 2 to the Second Reviewer Report  
ID: Physchem-3825138 
September 1, 2025  
We greatly appreciate your thorough review of our manuscript and the valuable feedback 
provided. In response, we have revised the manuscript carefully in line with your 
recommendations. A detailed, point-by-point reply to each comment, along with the 
corresponding revisions, is presented below. 
Reviewer’s General Comment 
This study explored the effect of E-beam radiation on gellan conformations in dilute 
aqueous solutions. It provided a reference basis for the structural and conformational 
changes of colloid under electron beam radiation. However, this work research is too 
simplistic and requires major revisions to enrich it. 
Response 
We thank the reviewer for this guiding comment; please see the revised manuscript. 
Reviewer’s Comment 1  
In the abstract, the author needs to demonstrate why this research is being conducted, 
as well as the urgency and necessity of this work. 
Response  
We thank the reviewer for this valuable comment. The abstract has been revised to 
include your comment (see revised Abstract) 
Reviewer’s Comment 2  
The first five paragraphs of the introduction are mostly about popularizing knowledge of 
polymer physics. However, the introduction did not provide a good elaboration on 
issues such as why this research was conducted, the current status of this research, and 
the innovative points of this research.  
Response  
We appreciate this observation. The introduction has been completely revised in order 
to consider your observatins revised. (See revised Introduction) 
Reviewer’s Comment 3 
2.3 and 2.5 belong to the test content and should be transferred to the characterization 
of 2.6. 
Response 
We agree with the reviewer and have transferred them to the characterization of 2.6 
(see Section 2). 
Reviewer’s Comment 4 
All the pictures related to the results in the figure lack scales and need to be improved. 
Response 
We have improved these pictures (see the improved figures in the manuscript). 
Reviewer’s Comment 5 
In Figures 1 to 6, there is only one influence of radiation on the gellan performance, which 
isunscientific. Moreover, the content is only limited to describing the result and does not 
provide an in-depth explanation of the reasons for the result. 
Response 
We appreciate this observation and we have considered it in section 3.1 in the revised 
manuscript. 
Reviewer’s Comment 6 
The conclusion section should not be presented in a bullet-point format but should be 
modified to a paragraph format. 
Response 
As suggested, the conclusion section have been modified to a paragraph format( see the 
comments in the revised manuscript). 
Reviewer’s Comment 7 
The cited literature is too outdated to reflect the prospective nature of this research. 
Response 
We are grateful to the reviewer for raising this significant point. The reference list has 
been revised to include more recent publications (2014–2025) addressing electron
beam degradation of polysaccharides, gellan gum properties, and polymer scaling laws, 
ensuring a more up-to-date representation of the field. 
Sincerely yours  
Nada Elzawi (On behalf of the authors) 
nada.elzawi@uob.edu.ly

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have improved their manuscript in accordance with the suggested recommendations, however, there are still a few questions and comments that remain, which are presented below.

1) The introduction must clearly formulate the purpose of this study.

2) In section 2.3, kGy is indicated instead of Gy. Otherwise, in this case, the indicated dose range significantly exceeds sterilization doses. Information about the accelerator and electron energy must be returned to this section.

3) The phrase "After that point no major reduction were seen" (Line 141) could be reformulated. Since it is not clear by what criterion the authors evaluate the significance of the change in molar mass. In the range of 0-200 Gy this reduction was approximately 13 kg/mol, and in the range of 200-450 Gy the reduction was about 8 kg/mol. Yes, this reduction is smaller, but why do the authors call it insignificant? It can be pointed out that after the point of 200 Gy the rate of reduction of molecular mass decreases. Also, the authors do not discuss the reason for such a change. Probably, the oxygen present in the solution and contributing to the rupture of polymer chains burns out at a dose of 200 Gy and above, and then the irradiation occurs in oxygen-free conditions?

4) Why do the ordinate axes in Figures 4 and 6 have dimensions? It is necessary to either remove them completely, or add the dimension of the quantity itself in additional brackets (lnRg(nm))

5) Still Figures 7 and 8 do not contain a complete legend.

6) Rephrase the sentence «As in Table 2, e-beam radiation led to a decrease in molar masses Ms and activation energies 𝐸[η]s of Gellan in solution, while it increased the entropy ∆𝑆 of Gellan in solution».

Author Response

Response Letter to the Reviewer 1

ID: Physchem-3825138

September 14, 2025

Dear Reviewer, We thank you for the additional evaluation and constructive feedback. Below we address each point in order

1. Clarify study purpose in the Introduction Comment: The introduction must clearly formulate the purpose of this study. Response: We have rewritten the final paragraph of the Introduction to state the study aim explicitly: “ The objective of this research was to conduct a systematic investigation into how low-dose e-beam radiation alters the molar mass, scaling behavior, and molecular conformation of aqueous Gellan gum solutions.”
2. Unit correction and accelerator details Comment: Section 2.3 uses kGy instead of Gy; indicate accelerator/electron-energy details. Response: We thank you for this valuable comment, please see the revised Section 2.3 in physchem-3825138.
3.   Reformulate “After that point no major reduction…” and discuss significance Comment: Clarify criterion for “significance” and explain the reduced slope after 200 Gy. Response: The sentence has been revised to read: “…Beyond 200 Gy the rate of molar-mass decrease diminished to ~8 kg mol⁻¹, indicating a lower scission probability once oxygen in the solution was consumed.” We now justify the criterion for significance and discuss oxygen depletion as the likely cause.
4. Ordinate axes in Figures 4 and 6 Comment: Add units or remove them entirely. Response: Figure captions and axis labels have been updated to remove the dimension of ln Rg and ln A2 (Figures 4 and 6).
5. Legends for Figures 7 and 8 Comment: Legends remain incomplete. Response: Figure legends have been Expanded to consider your comment (Figures 7 and 8. In physchem-3825138)
6. Rephrase Table 2 sentence Comment: Rephrase “As in Table 2…” sentence. Response: Revised to: “As summarized in Table 2, electron-beam irradiation decreased the molar mass (Ms) and activation energies () of gellan in solution, while increasing its entropy ().”

 

Sincerely yours

Nada Elzawi (On behalf of the authors)

nada.elzawi@uob.edu.ly

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The author has revised it as required and the current version can be accepted.

Author Response

Response Letter to the Reviewer 2

ID: Physchem-3825138

September 14, 2025

 

 

Dear Reviewer, We sincerely thank you for your thorough evaluation and for recommending acceptance of our manuscript. We are grateful for your positive feedback on the introduction, research design, methods, results, and presentation of figures and tables. Thank you for your time and constructive assessment.

 Kind regards,

Nada Elzawi (On behalf of the authors)

nada.elzawi@uob.edu.ly

Author Response File: Author Response.pdf