Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have submitted a review article, which mainly focus on the utilization of food waste by-products of plant and animal origin and their incorporation in PLA-based packaging materials for the development of novel packaging technology to extend the shelf-life of different foods. PLA has the advantages of biodegradability, high mechanical resistance, nontoxicity, and so on. But the disadvantages of PLA for its usage from food industries as a food packaging material are its low heat resistance capacity, weakness as a gas barrier, high brittleness, as well as relative high cost. While some food waste of plants and animals can act as additives, to improve the shortages of PLA.

This topic seems very meaningful, as food waste and food waste by-products are very important on the basis of circular economy. Surely, some issues should be carefully considered and corrected.

1. Section 1, Line 159-170, this part is a summary of the following part, and it is suggested to supplement the following classification basis (Section 2-6).

2. Why PLA is chosen as the research object? Is there any report on PLA as a food packaging material? If so, it’s best to added it in Section 1, when introducing PLA.

3. Discussion is Section 7; Conclusions is Section 8.

4. In Discussion, the problems when incorporating food waste by-products into PLA-based packaging materials should be provided.   

Author Response

 

DETAILED RESPONSE TO REVIEWERS’ COMMENTS

We thank the Reviewers who evaluated our study. The comments received were constructive since these helped us to improve our study. There has been an effort to cover adequately all comments. All changes are marked in red color within the revised manuscript. In addition, we have improved the English language through the manuscript.

 

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Reviewer 1#

The authors have submitted a review article, which mainly focus on the utilization of food waste by-products of plant and animal origin and their incorporation in PLA-based packaging materials for the development of novel packaging technology to extend the shelf-life of different foods. PLA has the advantages of biodegradability, high mechanical resistance, nontoxicity, and so on. But the disadvantages of PLA for its usage from food industries as a food packaging material are its low heat resistance capacity, weakness as a gas barrier, high brittleness, as well as relative high cost. While some food waste of plants and animals can act as additives, to improve the shortages of PLA.

This topic seems very meaningful, as food waste and food waste by-products are very important on the basis of circular economy. Surely, some issues should be carefully considered and corrected.

Response

We thank the Reviewer for the initial evaluation of our study and the acknowledgments of the studied topic he/she reported.

1. Section 1, Line 159-170, this part is a summary of the following part, and it is suggested to supplement the following classification basis (Section 2-6).

Response

There has been a revision in these parts so there is not any repeat of information and the manuscript has an independent flow considering these sections. Kindly see the revised lines.

1. Why PLA is chosen as the research object? Is there any report on PLA as a food packaging material? If so, it’s best to added it in Section 1, when introducing PLA.

Response

The reason why PLA was chosen as a research object, along with the reports found for the use of PLA as a food packaging material have now been added in the Introduction section. See revised text in lines 114-124.

1. Discussion is Section 7; Conclusions is Section 8.

Response

Corrected accordingly. However, given the comments by the other Reviewers sections have now been re-formulated. Kindly see through the revised manuscript.

4. In Discussion, the problems when incorporating food waste by-products into PLA-based packaging materials should be provided.   

Response

There has been an effort to discuss more efficiently the problems when incorporating food-waste by-products into PLA-based packaging materials. For your convenience, kindly see revised text in lines 622-631.

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Reviewer 2 Report

Comments and Suggestions for Authors

Food waste and its by-products have become a focus in the circular economy for developing novel packaging materials like PLA-based options that protect food and reduce plastic use. This review highlights recent trends and challenges in using plant and animal by-products to fortify PLA for extending food shelf life, while noting gaps in utilizing materials like onion peels, grape pomace, and whey.

1. The title mentioned “characterization” of PLA-based biogradable packing materials, however, no related characterization was shown in main text.

2. How can the scalability of using food waste by-products in PLA-based packaging materials be improved for commercial production?

3. The authors explored the utilization of various plant-based and animal-derived by-products in the development of PLA-based biodegradable packaging materials. Among the options presented, which category of by-products holds greater potential for practical application in real-world production, considering factors such as availability, cost-effectiveness, and functional properties? It would be better to provide a comparison of the properties of PLA films fortified with plant-based versus animal-derived by-products to determine which may offer superior performance.

Author Response

DETAILED RESPONSE TO REVIEWERS’ COMMENTS

We thank the Reviewers who evaluated our study. The comments received were constructive since these helped us to improve our study. There has been an effort to cover adequately all comments. All changes are marked in red color within the revised manuscript. In addition, we have improved the English language through the manuscript.

Reviewer 2#

Food waste and its by-products have become a focus in the circular economy for developing novel packaging materials like PLA-based options that protect food and reduce plastic use. This review highlights recent trends and challenges in using plant and animal by-products to fortify PLA for extending food shelf life, while noting gaps in utilizing materials like onion peels, grape pomace, and whey.

1. The title mentioned “characterization” of PLA-based biogradable packing materials, however, no related characterization was shown in main text.

Response

Dear Reviewer, we respect this comment. But kindly remember that this is a review article that comprises the thematic issue of a PhD work. In this context, the term ‘’characterization’ now in the review article has the meaning of critically evaluating the studies in the field, the trends and challenges. Yes, we agree with your input, that in experimental studies the term characterization means the analytical characterization of the studied matrices. In this context, we have changed the word ‘’characterization’’ with ‘’valuation’’ to meet your criteria (P.S. We believe that perhaps the word ‘’characterization’’  could be retained).

2. How can the scalability of using food waste by-products in PLA-based packaging materials be improved for commercial production?

Response

There has been an effort to provide more clearly how the scalability of using food waste by-products in PLA-based packaging materials be improved for commercial production. See revised text in lines 648-652.

3. The authors explored the utilization of various plant-based and animal-derived by-products in the development of PLA-based biodegradable packaging materials. Among the options presented, which category of by-products holds greater potential for practical application in real-world production, considering factors such as availability, cost-effectiveness, and functional properties? It would be better to provide a comparison of the properties of PLA films fortified with plant-based versus animal-derived by-products to determine which may offer superior performance.

Response

We have now tried to propose categories of food waste by products that may enhance better the production of PLA-based films in the real-world (market). Kindly see lines 654-661. Regarding your comment about the superior performance of plant-based versus animal-derived by products Table 1 provides this information. Yes, we have now discussed briefly the suggested performances of these food waste by products (lines 663-666) to avoid repeatability of information.

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Reviewer 3 Report

Comments and Suggestions for Authors

The review article is interesting, however it needs substantial modification before further consideration.

1- The abstract is vaguely written. Use short sentences to clearly define the problems and highlight the specific areas covered in this review.

2- Include sections on animal waste and synthetically produced waste. Arrange the paragraphs sequentially to maintain the contextual flow. Add up-to-date references throughout the introduction.

 3- Line 80, Page 2, Clarify whether "140,000 tons every year" refers to PLA specifically or all bioproducts. If it is general data about biopolymers, mention PLA specifically and include an appropriate reference.

4- Pages 2–3, Lines 83–110, Expand on the use and recycling of plastic and its waste. Refer to https://doi.org/10.1016/j.cej.2025.159304 for detailed information.

5- Figure 1, Retrieve the data from Scopus and provide it as supplementary material. Compare this data with research on other biopolymers, potentially as a bar chart for better visualization.

6- Figure 2, Provide the source of the data used in this figure and add a reference.

7- Break long paragraphs into shorter segments for clarity in the Disucssion section. Cite references next to specific reasoning or claims to maintain credibility and readability.

8- Line 532, Regarding collagen from fish, add a suitable reference such as https://doi.org/10.3390/polym13203458.

 9- Rewrite the conclusion with precise sentences and quantifiable data to summarize the findings effectively.

Comments on the Quality of English Language

Please check minor typos before revised submission.

Author Response

DETAILED RESPONSE TO REVIEWERS’ COMMENTS

We thank the Reviewers who evaluated our study. The comments received were constructive since these helped us to improve our study. There has been an effort to cover adequately all comments. All changes are marked in red color within the revised manuscript. In addition, we have improved the English language through the manuscript.

Reviewer 3#

The review article is interesting, however it needs substantial modification before further consideration.

Response

We thank the Reviewer for the initial evaluation of our study and the acknowledgments of the studied topic he/she reported.1- The abstract is vaguely written. Use short sentences to clearly define the problems and highlight the specific areas covered in this review.

Response

Abstract has now been modified according to Reviewer’s comments to define more clearly the problems and the specific thematic areas studied in this review article.

2- Include sections on animal waste and synthetically produced waste. Arrange the paragraphs sequentially to maintain the contextual flow. Add up-to-date references throughout the introduction.

Response

Dear Reviewer, we have now divided the sections into food waste by-products of plant origin and food waste by-products of animal origin according to your suggestions. The Introduction and figure 2 has now been updated with references.

 3- Line 80, Page 2, Clarify whether "140,000 tons every year" refers to PLA specifically or all bioproducts. If it is general data about biopolymers, mention PLA specifically and include an appropriate reference.

Response

The Reviewer is right, yes it refers to PLA. We made some changes to be better understood. References were added according to your suggestion.

4- Pages 2–3, Lines 83–110, Expand on the use and recycling of plastic and its waste. Refer to https://doi.org/10.1016/j.cej.2025.159304 for detailed information.

Response

Added accordingly in the Introduction section. See revised text in lines 108-112.

5- Figure 1, Retrieve the data from Scopus and provide it as supplementary material. Compare this data with research on other biopolymers, potentially as a bar chart for better visualization.

Response

Data from Scopus showing the use of PLA and other biopolymers have now been inserted in a figure in a form of bar charts as Figure 1. We believe that such a figure should be retained to provide the readers the relevant information you suggested. The original Figure 1 has now been moved to Supplementary material given that provides valuable information about the research on PLA the last 20 years.

6- Figure 2, Provide the source of the data used in this figure and add a reference.

Response

We added the appropriate references that were used to retrieve the data. We made some changes, while the references provided the cost in USD, and we modified them and provided in EUR.

7- Break long paragraphs into shorter segments for clarity in the Disucssion section. Cite references next to specific reasoning or claims to maintain credibility and readability.

Response

Done accordingly.

8- Line 532, Regarding collagen from fish, add a suitable reference such as https://doi.org/10.3390/polym13203458.

 Response

Added accordingly the suggested reference with a relevant comment. See lines 551-553.

9- Rewrite the conclusion with precise sentences and quantifiable data to summarize the findings effectively.

Response

The conclusion has now been rewritten to be more precise and fit better with the findings of the review article.

 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have thoroughly revised the article, and it is now suitable for publication in the Sustainability journal.