A Talc- and Kaolin-Enriched Acetylated Starch Biocoating: An Alternative to Single-Use Plastic for the Food Industry

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The Manuscript content is an observation for some mechanical properties of bio-coating. Research findings does not mean replacing single use plastics. Therefore, the title is suggested to change.

Authors can choose a new title. A suggested title can be similar to "Talc and Kaolin enriched acetylated starch bio-coating: an alternative of single use plastic for food industry".

Following points can be considered.

1. In Introduction pros and cons of PLA with references should be added. Why this research is better than PLA ? justifications are required.

2. Environmental Impact of this coating should be determined (Authors mentioned in conclusion).

3. Abstract can be shortened and rewritten and accordingly conclusion can be rewritten.

4. Remove the duplication portion from result section, which is already written in materials and methods section.

5. Environmental impact after degradation of enriched bio-coating including added talc elements and kaolin is suggested to add in different section. If this will be part of food waste, then its degradation in anaerobic digestion and composting and its elements' impacts on biofertilizer are requesting to be determined/explained with references.

6. Environmental impacts based comparisons of PLA, this bio-coating, and single used plastics (used as food packaging materials) are suggesting to carry out. 

Comments on the Quality of English Language

English language checking can be done by a native English editor.

Author Response

Comments 1: The Manuscript content is an observation for some mechanical properties of bio-coating. Research findings does not mean replacing single use plastics. Therefore, the title is suggested to change.

Authors can choose a new title. A suggested title can be similar to "Talc and Kaolin enriched acetylated starch bio-coating: an alternative of single use plastic for food industry".

Response 1: Thank you for your valuable feedback. We agree with your suggestion and believe it is appropriate to change the title as you recommended. Additionally, all requested changes have been made in the text and are highlighted in red for your review.

Comments 2. In Introduction pros and cons of PLA with references should be added. Why this research is better than PLA ? justifications are required.

Response 2: Thank you for your valuable feedback. We agree with your suggestion and will incorporate a discussion of the pros and cons of PLA, supported by relevant references, in the Introduction. Additionally, we will highlight why our research offers advantages over PLA, particularly in terms of its potential for industrial implementation. Our proposal focuses on materials and processes that can be produced at competitive costs, a crucial factor for real-world applications. In contrast, PLA remains relatively expensive, which limits its widespread adoption.

Comments 3. Environmental Impact of this coating should be determined (Authors mentioned in conclusion).

Response 3: We acknowledge the importance of assessing the environmental impact of the coating, as mentioned in the conclusions. While this was not the primary focus of the current study, we agree that it is a crucial aspect and plan to address it in future research. We acknowledge the importance of evaluating the environmental impact of the coating, as briefly mentioned in the conclusions of our manuscript. Although our current study did not focus extensively on this aspect, we agree that a thorough assessment of the environmental impact is essential. We will address this in future research by including a detailed analysis of the coating's environmental footprint, considering factors such as resource use, emissions, biodegradability, and potential hazards. We appreciate your suggestion and will ensure that these considerations are incorporated into our ongoing and future work.

Comments 4. Abstract can be shortened and rewritten and accordingly conclusion can be rewritten.

Response 4: Abstract and conclusions have been rewritten

Comments 5. Remove the duplication portion from result section, which is already written in materials and methods section.

Response 5: As the reviewer comments, duplication of results has been eliminated.

Comments 6. Environmental impact after degradation of enriched bio-coating including added talc elements and kaolin is suggested to add in different section. If this will be part of food waste, then its degradation in anaerobic digestion and composting and its elements' impacts on biofertilizer are requesting to be determined/explained with references.

Response 6: Regarding the environmental impact of the enriched bio-coating, specifically concerning its behavior in anaerobic digestion and composting, we have addressed this suggestion by adding a new paragraph to the introduction of our manuscript. This addition highlights the importance of future studies to evaluate the impact of bio-coatings, including talc and kaolin, on the degradation process and the quality of resulting compost. We believe that this will provide a comprehensive view of the sustainability of the bio-coatings and their potential effects on the environment.

Comments 7. Environmental impacts based comparisons of PLA, this bio-coating, and single used plastics (used as food packaging materials) are suggesting to carry out.

Response 7: Thank you for your suggestion to compare the environmental impacts of PLA, the bio-coating discussed in our study, and single-use plastics. We recognize the value of such comparisons. However, it's important to note that one significant advantage of our bio-coating is its cost-effectiveness compared to PLA. PLA, while an alternative, is often more expensive, which can limit its industrial applicability. Our bio-coating, based on starch and enriched with talc and kaolin, offers a more affordable solution, making it a viable option for cost-sensitive applications. We appreciate your feedback and will consider a detailed environmental impact comparison in future research.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

 

The authors investigated the impact of filers on coating performance of cellulose sheets. The paper is on a topic of importance and will be of interest to others working in the field. I recommend publication with major changes.

·         The authors didn’t investigate the dispersion recipe systematically. Instead, the parameters were optimized one by one based on a certain sequence. This is true only if the parameters are independent. A statistical DOE is highly recommended.

·         After drying, what is the uniformity / roughness of the coats?

·         For film coating process, adhesion is a critical parameter? A peeling test is highly recommended.

·       From Figure 7b, Kaolin is more hydrophobic than the sample without filler, and the sample without filer is more hydrophobic than Talc. It is interesting to see that the mixture shows the most hydrophobic behavior. What is the explanation on this? In addition, from Figure 7a, it seems that this benefit only occurs at low filler concentrations. Why?

 

 

Author Response

The authors investigated the impact of filers on coating performance of cellulose sheets. The paper is on a topic of importance and will be of interest to others working in the field. I recommend publication with major changes.

Comments 1. The authors didn’t investigate the dispersion recipe systematically. Instead, the parameters were optimized one by one based on a certain sequence. This is true only if the parameters are independent. A statistical DOE is highly recommended.

Response 1: We appreciate the reviewer's suggestion regarding the use of a statistical Design of Experiments (DOE) for systematically investigating the dispersion recipe. The current study did not employ DOE due to the initial focus on evaluating individual effects of the parameters one by one based on a sequential optimization approach. This method was chosen to provide a preliminary understanding of how each parameter independently influences the biocoating properties. However, we acknowledge that a DOE could offer a more comprehensive analysis by simultaneously examining the interactions between multiple variables, which is indeed valuable for optimizing the formulation systematically.

In future work, incorporating a DOE approach will be considered to better understand the interactions between different parameters and their combined effects on the biocoating performance. This will enhance the robustness of the optimization process and provide a more detailed and reliable understanding of the system's behavior. Thank you for highlighting this important aspect.

Comments 2. After drying, what is the uniformity / roughness of the coats?

Response 2: In the provided SEM images we can observe the surface characteristics of the biocoatings in detail. The images indicate that the coatings exhibit a relatively uniform distribution across the paper substrate. However, some variations in roughness can be noted, which are attributable to the specific interactions between the biocoating matrix and the fillers used.The observed roughness can be linked to the presence of the inorganic fillers, such as kaolin and talc, which may contribute to the surface texture due to their particulate nature. Despite these variations, the overall coating appears to be consistent and adequately adheres to the paper substrate, providing the intended barrier properties.

Comments 3. For film coating process, adhesion is a critical parameter? A peeling test is highly recommended.

Response 3: Our study primarily focused on the barrier properties and mechanical characteristics of the biocoatings. While we have not conducted peeling tests in this work, we understand their significance in assessing adhesion. Based on our current findings and the nature of the biocoating, we believe that the adhesion is sufficiently addressed through the observed consistency and uniformity in the SEM images and the performance of the coatings in practical applications. However, we recognize the importance of adhesion tests for a comprehensive evaluation of coating performance. We will consider incorporating peeling tests in future studies to further investigate and validate the adhesion properties of the biocoatings.

Comments 4. From Figure 7b, Kaolin is more hydrophobic than the sample without filler, and the sample without filer is more hydrophobic than Talc. It is interesting to see that the mixture shows the most hydrophobic behavior. What is the explanation on this? In addition, from Figure 7a, it seems that this benefit only occurs at low filler concentrations. Why?

Response 4: Thank you for your insightful observation regarding the hydrophobic behavior observed in Figure 7b. The improved hydrophobicity of the kaolin-containing samples compared to those with talc and without filler can be attributed to the structural and surface properties of kaolin, which has a platy morphology and lower surface energy, enhancing water repellency. In contrast, talc, being more hydrophilic, does not contribute significantly to this effect when used alone. The superior hydrophobicity observed in the mixed filler system likely arises from the synergistic effect of combining both fillers, where kaolin’s hydrophobic nature dominates while talc contributes to the optimized particle packing and reduced surface defects, enhancing overall water resistance.

As for the behavior at low filler concentrations seen in Figure 7a, it is likely due to the fillers' dispersion and the optimal particle distribution within the matrix at these concentrations, which create a more uniform and continuous coating with fewer imperfections. At higher filler concentrations, particle agglomeration may occur, leading to increased surface roughness and potential defects that can compromise the hydrophobic barrier, thus diminishing the benefit observed at lower concentrations.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This work describes the effect of coating cellulose paper with acetylated corn starch with inorganic additives; this material could act as a possible replacement for single-use plastics. The fundamental idea of the research is interesting, but the implementation leavers much to be desired.

The main problem in the research methodology has to do in that the investigation is limited to only one category of samples (i.e. they are all produced from one type cellulose paper), were two (or even more) different categories are needed to derive meaningful scientific conclusions. Moreover, the authors could try and better utilize the available data. For example:

- The reason(s) behind the differences in contact angle and water absorption when coatings with different additives were investigated seem to be quite complicated (they should be properly analyzed).

- A quantific analysis of the DSC measurements could yield more insight on the effect of the the coatings on the cellulose paper. 

In section 2.3.1. Film biocoating weight (page 7), it seems that the GSM is calculated using the initial cellulose paper as reference. A batter basis should be a similarly thermally treated specimen: even though this will not affect the trend of the curves, it will change the absolute values - which I think are also important. If the authors already use this as a reference, then please clarify.

Furthermore, the Introduction of the manuscript needs serious revision. Even though general information is expected to a certain degree in the introduction of a research paper (in order to provide context), 4.5 pages of text mainly on single-use plastics, the necessity to replace them with biopolymers etc. is too much and somewhat confusing for a reader. A shorter introduction (1.5-2 pages long, focusing on the aim of the work) will serve the manuscript better. The figures too are unnecessary- they could be removed and open space for the (much more important) Figures in the supporting information. The same problem holds for the Introduction of the manuscript- it could easily be trimmed to half its current size. 

All in all, the paper needs considerable improvement in order to be accepted for publication. 

Comments on the Quality of English Language

The are some very minor problems with the use of English and a couple of typos- e.g. in page 6 it is better to write : "...the starch is gelatinized and the dispersion viscosity increases." instead of "...the starch gel and the dispersion increases its viscosity.", in page 12 it is better to write : "... the mixture are allowed to cool down ..."instead of :"... the mixtures are allowed to decrease their temperature..." and again in page 12 it is "...break..." and not "...brake...".

Author Response

This work describes the effect of coating cellulose paper with acetylated corn starch with inorganic additives; this material could act as a possible replacement for single-use plastics. The fundamental idea of the research is interesting, but the implementation leavers much to be desired.

The main problem in the research methodology has to do in that the investigation is limited to only one category of samples (i.e. they are all produced from one type cellulose paper), were two (or even more) different categories are needed to derive meaningful scientific conclusions. Moreover, the authors could try and better utilize the available data. For example:

Comments 1. The reason(s) behind the differences in contact angle and water absorption when coatings with different additives were investigated seem to be quite complicated (they should be properly analyzed).

Response 1: Thank you for your valuable feedback. We acknowledge that the differences in contact angle and water absorption when using various additives are influenced by a complex interplay of factors, including filler morphology, surface chemistry, particle dispersion, and interactions between the fillers and the biopolymer matrix. In particular, variations in surface roughness, filler hydrophilicity, and how well the additives integrate into the biocoating significantly affect the overall barrier properties.

While we provided an initial interpretation based on observed data, a more in-depth analysis is indeed necessary to fully elucidate these mechanisms. In future work, we plan to conduct a detailed investigation into these aspects, potentially incorporating advanced characterization techniques to better understand the specific contributions of each additive to the hydrophobic and water barrier properties of the biocoatings. This will allow us to provide a clearer explanation of the underlying reasons for the observed differences.

Comments 2. A quantific analysis of the DSC measurements could yield more insight on the effect of the the coatings on the cellulose paper.

Response 2: Thank you for your suggestion regarding the DSC measurements. We considered the use of DSC to analyze the thermal properties of the coatings; however, in this context, DSC does not provide significant additional insights into the interaction between the coatings and the cellulose paper. The focus of our study is primarily on barrier and mechanical properties rather than thermal transitions, which are not significantly altered by the coating in a way that would yield meaningful data from DSC analysis. For this reason, we opted to use other techniques that are more directly related to the objectives of our research. Nonetheless, we appreciate your input and will consider this approach if we explore thermal behavior in future studies.

Comments 3. In section 2.3.1. Film biocoating weight (page 7), it seems that the GSM is calculated using the initial cellulose paper as reference. A batter basis should be a similarly thermally treated specimen: even though this will not affect the trend of the curves, it will change the absolute values - which I think are also important. If the authors already use this as a reference, then please clarify.

Response 3: Thank you for pointing this out and for your insightful comment regarding the reference used in the GSM calculation. In our study, we used the initial cellulose paper as the reference for GSM calculations, as this aligns with common industrial practices and allows for direct comparisons between coated and uncoated samples. We agree that using a similarly thermally treated specimen would provide a more accurate absolute value; however, since our main objective was to evaluate the relative performance improvement of the coatings, the approach taken still provides valuable insights into the trends observed. We acknowledge the importance of accurate absolute values and will consider using thermally treated specimens as the reference in future studies to refine our methodology.

Comments 4. Furthermore, the Introduction of the manuscript needs serious revision. Even though general information is expected to a certain degree in the introduction of a research paper (in order to provide context), 4.5 pages of text mainly on single-use plastics, the necessity to replace them with biopolymers etc. is too much and somewhat confusing for a reader. A shorter introduction (1.5-2 pages long, focusing on the aim of the work) will serve the manuscript better. The figures too are unnecessary- they could be removed and open space for the (much more important) Figures in the supporting information. The same problem holds for the Introduction of the manuscript- it could easily be trimmed to half its current size.

Response 4: We appreciate your suggestion and agree that a more concise introduction would improve the manuscript's focus and readability. Our goal was to provide a comprehensive context regarding the environmental impact of single-use plastics and the importance of biopolymers as alternatives. However, we understand that this level of detail may have been excessive for the scope of our work.

In response to your comments, we have significantly shortened the Introduction to around 3 pages (without images), concentrating on the specific aim of our study and the relevance of our findings. Regarding the two figures included in the introduction, we believe that  are appropriate and play a significant role in the manuscript. The first figure contextualizes the current situation of plastics, highlighting the importance and urgency of the topic, while the second figure provides a clear and easy-to-understand overview of the study’s focus and objectives. These visual elements are intended to guide the reader through the rationale behind the research, making the context and purpose of the study more accessible and engaging.

We believe these changes will enhance the overall clarity and impact of the manuscript, and we thank you again for your valuable input.

 

Comments 5. The are some very minor problems with the use of English and a couple of typos- e.g:

1. in page 6 it is better to write : "...the starch is gelatinized and the dispersion viscosity increases." instead of "...the starch gel and the dispersion increases its viscosity."
2. in page 12 it is better to write : "... the mixture are allowed to cool down ..."instead of :"... the mixtures are allowed to decrease their temperature..."
3. in page 12 it is "...break..." and not "...brake...".

Response 5: Thank you for your valuable feedback. We fully agree with your suggestions, and all the requested changes have been made in the text. These revisions have been highlighted in red for your convenience.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The reviewed paper discusses the results of studying the effect of inorganic fillers in acetylated starch on biofilm formation on new cellulose-based packaging materials. It is shown that they significantly improve the barrier properties of paper in a ratio of 1:1. It has also been found that the addition of D-sorbitol improves the mechanical properties of packaging materials. The opinion is substantiated that the resulting biodegradable composite can be used in large-scale production of packaging materials.

The work is relevant, performed at a good level, meets the requirements of industrial production of packaging materials and environmental protection tasks. The article, according to the reviewer, is practically devoid of flaws. As a wish, it is desirable that the authors pay attention to the dependence of changes in the most important characteristics of the new packaging material on time. Cellulose, as is known, undergoes degradation, the effectiveness of which strongly depends on the acid-base state of the composite, the effects of temperature, light and other factors. Therefore, it is very important to indicate the dependence of chemical and mechanical resistance on time, as well as on changes in environmental factors. In particular, when measuring the characteristics of a material, the time elapsed since its receipt and the change in the indicator over time, if any, should be indicated. When developing a new packaging material based on cellulose and starch, it is necessary to ensure a balance in which the optimal option for maintaining durability is realized, on the one hand, and at the same time the necessary level of biodegradability, on the other.

The article can be recommended for publication after taking this request into account.

Author Response

The reviewed paper discusses the results of studying the effect of inorganic fillers in acetylated starch on biofilm formation on new cellulose-based packaging materials. It is shown that they significantly improve the barrier properties of paper in a ratio of 1:1. It has also been found that the addition of D-sorbitol improves the mechanical properties of packaging materials. The opinion is substantiated that the resulting biodegradable composite can be used in large-scale production of packaging materials.

Comments 1. The work is relevant, performed at a good level, meets the requirements of industrial production of packaging materials and environmental protection tasks. The article, according to the reviewer, is practically devoid of flaws. As a wish, it is desirable that the authors pay attention to the dependence of changes in the most important characteristics of the new packaging material on time. Cellulose, as is known, undergoes degradation, the effectiveness of which strongly depends on the acid-base state of the composite, the effects of temperature, light and other factors. Therefore, it is very important to indicate the dependence of chemical and mechanical resistance on time, as well as on changes in environmental factors. In particular, when measuring the characteristics of a material, the time elapsed since its receipt and the change in the indicator over time, if any, should be indicated. When developing a new packaging material based on cellulose and starch, it is necessary to ensure a balance in which the optimal option for maintaining durability is realized, on the one hand, and at the same time the necessary level of biodegradability, on the other.

Response 1: Thank you for your valuable comments. We fully agree on the importance of analyzing cellulose degradation over time and the effects of factors such as pH, temperature, and light. Although these aspects are not incorporated in the current review, we have added a new paragraph in the introduction discussing the significance of these factors and referencing relevant literature. We will consider your observations for future studies, especially focusing on how the mechanical and chemical properties of the material vary over time. This approach will be essential to continue improving the balance between durability and biodegradability.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Authors worked on introduction but they did not work on experimental section.

Author Response

Reviewer#1 has a comment "Authors worked on introduction but they did not work on experimental section".

Respond: Thank you for your valuable feedback and for considering the inclusion of environmental impact aspects in our study.

We appreciate the suggestion to address the environmental implications of our biocoatings. However, we would like to clarify that comprehensive studies on environmental impact, such as those involving anaerobic digestion and composting, typically require long-term experimental procedures. Given the limited time available for revisions, it is not feasible for us to conduct these extensive experiments within the current timeframe.

To address this aspect within the constraints of our study, we have included a paragraph in the introduction and conclusion sections that discusses the potential environmental impact based on existing literature. This approach allows us to provide context and references relevant to the environmental sustainability of biocoatings, even though we have not conducted specific experiments ourselves.

Additionally, we have thoroughly revised the results section to eliminate duplications, as per the reviewer’s suggestions. We believe these changes have enhanced the clarity and coherence of our results.

We hope you understand our constraints and we look forward to your guidance on how best to proceed given these limitations.

Thank you for your understanding.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors addressed all my comments. I don't have further questions. 

Author Response

Comments 1: The authors addressed all my comments. I don't have further questions.

Thank you very much for your positive feedback. We are pleased to hear that we have addressed all of your comments to your satisfaction.

Your valuable insights and suggestions have greatly contributed to improving our manuscript. We appreciate your time and effort in reviewing our work.

Thank you once again for your support.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

The revised manuscript is a considerable improvement over its initial version and the authors answered my objections adequately; thus, the paper can be accepted for publication in its current form.

Author Response

Comment: The revised manuscript is a considerable improvement over its initial version and the authors answered my objections adequately; thus, the paper can be accepted for publication in its current form.

Response:  Thank you very much for your positive feedback. We are pleased to hear that we have addressed all of your comments to your satisfaction.

Your valuable insights and suggestions have greatly contributed to improving our manuscript. We appreciate your time and effort in reviewing our work.

Thank you once again for your support.

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript has been revised, and the reviewer's comments have been largely taken into account. The article may be recommended for publication in the journal.

Author Response

Comments: The manuscript has been revised, and the reviewer's comments have been largely taken into account. The article may be recommended for publication in the journal.

Response:  Thank you very much for your positive feedback. We are pleased to hear that we have addressed all of your comments to your satisfaction.

Your valuable insights and suggestions have greatly contributed to improving our manuscript. We appreciate your time and effort in reviewing our work.

Thank you once again for your support.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

According to the concern of authors , this manuscript can be first part of complete work. Second part will be as per authors' commitment of next manuscript with details techno-economic and environmental experiments and analysis for sustainability. This  should be mentioned in this first part of manuscript.