Ionic Strength of Methylcellulose-Based Films: An Alternative for Modulating Mechanical Performance and Hydrophobicity for Potential Food Packaging Application

Round 1

Reviewer 1 Report

 

Comments to authors

The research findings in this article are the demand of current era. The development of renewable materials with enhanced properties and antimicrobial activity for packaging helps to reduce environmental damage caused by conventional packaging materials, especially in food industry. There are few suggestions to improve the manuscript for publication.

1. The title of the manuscript is too descriptive.
2. As, authors did not perform any experiment for active food packaging on the fruits as given in following manuscripts. It is recommended to use word “potential food packaging application” in the title.

Development and characterization of plant oil-incorporated carboxymethyl cellulose/bacterial cellulose/glycerol-based antimicrobial edible films for food packaging applications. 2022, Advanced Composites and Hybrid Materials, DOI: 10.1007/s42114-021-00408-9.

 

3. Mention the concentration of salt solutions and present quantitative data in the abstract. Also mention which concentration has better results comparable to others and how?

1. The Introduction and discussion can be strengthened by citing some recent relevant articles. You may read the following relevant articles.

• Biobased materials for active food packaging: A review. 2022, Food Hydrocolloids 125:107419.
• Development and characterization of Yeast-incorporated antimicrobial cellulose biofilms for edible food packaging applications. Polymers 13(14):2310

5. Authors should test the material on real food items as active food packaging material.
6. Replace the word “which” with “where” in the description of each equation e.g at line 100 and 145. Also check through whole manuscript and replace with appropriate words.
7. In table 2, unify the measurement scale for all inhibition zone data. In the header row “mm” is given but with aureus and E. coli it is given in cm.
8. In figure 5B, why authors did not record the inhibition zone at various concentrations for coli? only 500 mM is mentioned for both salts. Authors should provide the results of all salts concentrations for E.coli too. Even if the results are not significant.
9. Through whole manuscript some references are cited with authors name and some are cited as a list such as line 186, 215, 226, 242 etc. Its recommended to follow the journal guidelines
10. Write the ionic valency in superscript at line 231
11. It is recommended to check whole manuscript for grammatical, typos and spelling mistakes.
12. For better presentation of the figures, unify the text of all figure especially Figure 1a, 1b, 2c, 2d etc

Comments for author File: Comments.pdf

Author Response

Dear editor and reviewers:

We sincerely appreciate all the reviewers and the editor for their thoughtful and professional critiques of our manuscript. We have adopted virtually all of the suggestions and revised the manuscript accordingly. We hope that the revised manuscript has been improved to the level of the reviewers’ satisfaction. Our point-by-point responses to reviewers’ comments are detailed in the attached file. Please see the attachment.

We hope that our manuscript will be acceptable for publication in Polysaccharides.

Author Response File: Author Response.docx

Reviewer 2 Report

This work studied the influence of ionic strength (IS) to modulate the physicochemical properties of methylcellulose (MC), by incorporating salts of LiCl or MgCl₂ into MC dispersions. It is proved that the MC films with hydrophobic surface, high elasticity, and flexibility can be manufactured by salts addition due to the IS forces modulation. It's a good research paper with clear and reasonable experimental design, detailed results and well-written manuscript. There are only a few minor issues in the text that need to be revised or explained, as follows:

1. In 2.2 section (Production of MC-based films and Active Films), the authors said that the film-forming solutions were poured into glass plates. How to get the MC films further? Does it still need to be scraped or simply baked off the solvent? How to control the thickness and uniformity of films?

In order to obtain more tough polymer film, it is necessary to prepare polymer film by the blade coating method. It is necessary to induce orientation by a certain external force, which will greatly improve the mechanical properties of polymer film.

2. In 3 section (Results), A discussion of material performance results is suggested in subsections, similar to the discussion in Section 2.
3. In the discussion of the optical transmittance of MC-based film, the actual photos of the representative samples added with LiCl or MgCl₂ are suggested to be given, and the film thickness should be unified as much as possible.
4. For the transmittance of MC-based films added with LiCl or MgCl₂ barrier against UV-Vis light, why does the transmittance decrease significantly at 250mM, especially at 500mM of LiCl, but there is no such change for the films of MgCl₂?
5. As the author states, the incorporation of LiCl or MgCl₂ into polymeric dispersions can modulate the ionic strength (IS). The authors directly treat the LiCl or MgCl₂ concentration as IS in the text, such as Figures 3 and 5. However, the concentration of ions is not directly equivalent to IS. This also leads to another question, what is the correspondence between ion concentration and IS? how to establish the relationship between them?
6. In Table 1 and 2, What does the superscript of a/b/c/d mean? Their respective meanings were not clearly given.
7. Other formatting errors, such as subscripts in MgCl2, capitalization issues in References 19 and 20, etc. It is recommended to read the full text carefully and make corrections.

Author Response

Dear editor and reviewers:

We sincerely appreciate all the reviewers and the editor for their thoughtful and professional critiques of our manuscript. We have adopted virtually all of the suggestions and revised the manuscript accordingly. We hope that the revised manuscript has been improved to the level of the reviewers’ satisfaction. Our point-by-point responses to reviewers’ comments are detailed as follows. "Please see the attachment."

We hope that our manuscript will be acceptable for publication in Polysaccharides.

Author Response File: Author Response.docx

Reviewer 3 Report

The objective of this study was to develop and investigate changes in methylcellulose-based films when incorporated with nisin and different concentrations of a monovalent salt (LiCl) or a divalent salt (MgCl2).
This is an extensive investigation, with a number of experimental analyses.
The work is interesting from scientific perspective and the proposed manuscript is thematically relevant to the scope of the journal. 
The overall organization and structure of the manuscript are appropriate, while the paper is well written. The goal of the manuscript is well described and the discussion is well approached. The methodology applied in the research is presented in clear manner, so that it is repeatable by other authors. The results and discussion well explained by cited literature data. The scientific novelty of the manuscript is clearly presented.
Some comments:
For the Abstract part is recommended to add some results in numerical form.
Lines 58-59 Note that nisin is not permitted in some countries.
Line 94. report the pH and temperature of the solution at the time of nisin addition. High pH and temperature may result in its partial inactivation.

Author Response

Dear editor and reviewers:

We sincerely appreciate all the reviewers and the editor for their thoughtful and professional critiques of our manuscript. We have adopted virtually all of the suggestions and revised the manuscript accordingly. We hope that the revised manuscript has been improved to the level of the reviewers’ satisfaction. Our point-by-point responses to reviewers’ comments are detailed in the attached file. Please see the attachment.

We hope that our manuscript will be acceptable for publication in Polysaccharides.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments to authors

The authors address some of the comments precisely but still some ambiguities need to be clarified before acceptance of the manuscript. Below are comments for authors to improve the quality of manuscript and to ensure truthfulness of experimental data.

1. In table 1. The measuring unit of the inhibition zone is changed from cm to mm but still the values are same as previous. Please clear this ambiguity in data and cross check with original experimental values.
2. The symmetry of figure 5 is not correct. In the main figure authors should provide the inhibition zone of both salts and different concentrations for both bacteria. Figure should be understandable in its own without jumping to supplementary file.
3. Unify the style of ‘Naisin-z’ through whole manuscript.

Author Response

We sincerely appreciate all the reviewers and the editor for their thoughtful and professional critiques of our manuscript. We have adopted virtually all of the suggestions and revised the manuscript accordingly. We hope that the revised manuscript has been improved to the level of the reviewers’ satisfaction. Our point-by-point responses to reviewer comments are detailed as follows. The same answers are available in the attached file. Please see the attachment.

 

Point 1: In table 1. The measuring unit of the inhibition zone is changed from cm to mm but still the values are same as previous. Please clear this ambiguity in data and cross check with original experimental values.

 

Response 1: We recheck the original data and the values are correct. The error was only in typing the unit. We appreciate your attention and concern.

 

 

Point 2: The symmetry of figure 5 is not correct. In the main figure authors should provide the inhibition zone of both salts and different concentrations for both bacteria. Figure should be understandable in its own without jumping to supplementary file.

 

Response 2: We thank the reviewer for careful observation. All photographs obtained of the antibacterial activity in symmetry were added. We chose not to add a line indicating the zone of inhibition, as all inhibition halos have already been shown in Table 1 and also to avoid visual pollution. Figure 1s of the supplemental material has been removed and added to Figure 5 as suggested.

 

 

Point 3: Unify the style of ‘Naisin-z’ through whole manuscript.

 

Response 3: Thank you for your careful observation. The style of  "Nisina-Z" was standardized.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have adopted the suggestions and revised the manuscript accordingly.

Author Response

Response to Reviewer 3 Comments

 

Dear editor and reviewer:

We thank the reviewer for the careful reviews and observations made. We revised the article again and fixed minor errors. We hope the article is suitable for publication in Polysaccharides.

Reviewer 3 Report

The authors have made the changes asked and the quality of the manuscript improved. The paper can be accepted in the present format.

Author Response

Response to Reviewer 3 Comments

 

Dear editor and reviewer:

We thank the reviewer for the careful reviews and observations made. We revised the article again and fixed minor errors. We hope the article is suitable for publication in Polysaccharides.

Round 3

Reviewer 1 Report

Accepted in the current form