Recent Advances in Protein Extraction Techniques for Meat Secondary Streams
, Yu Fu 2, Juárez Manuel 1, Ifedayo Emmanuel Bello 1,3, David Tinotenda Mbiriri 1,3, Ajibola Bamikole Oyedeji 3, Tawanda Tayengwa 1 and Jianping Wu 3Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsWhile the manuscript addresses a highly relevant topic in food sustainability and protein recovery, its current length of 66 pages significantly exceeds the typical format and expectations for a scientific journal article. The excessive length makes it difficult to read, absorb, and evaluate the key contributions of the work, and detracts from the overall clarity and focus of the manuscript.
Although the authors have included a comprehensive literature review and detailed discussion of various protein extraction techniques, the manuscript would benefit substantially from a more concise and focused presentation. Reducing the manuscript to a standard length (e.g., 12–20 pages of main text excluding references and figures) would help readers better grasp the novelty, implications, and applicability of the work.
Therefore, I strongly recommend a major revision focused on reducing the length of the manuscript, with clear prioritization of essential content, elimination of redundant explanations, and condensation of overly detailed background information into summarized tables or figures where appropriate.
Author Response
Comment
While the manuscript addresses a highly relevant topic in food sustainability and protein recovery, its current length of 66 pages significantly exceeds the typical format and expectations for a scientific journal article. The excessive length makes it difficult to read, absorb, and evaluate the key contributions of the work, and detracts from the overall clarity and focus of the manuscript.
Although the authors have included a comprehensive literature review and detailed discussion of various protein extraction techniques, the manuscript would benefit substantially from a more concise and focused presentation. Reducing the manuscript to a standard length (e.g., 12–20 pages of main text excluding references and figures) would help readers better grasp the novelty, implications, and applicability of the work.
Therefore, I strongly recommend a major revision focused on reducing the length of the manuscript, with clear prioritization of essential content, elimination of redundant explanations, and condensation of overly detailed background information into summarized tables or figures where appropriate.
Action: We appreciate the reviewer’s comments. We understand the review is longer than other documents, even after great efforts in our part to be concise. However, the material to be included in the review is extensive and we consider that reducing it to fit within a page limit would lead to losing valuable information. This could take away from the comprehensiveness and value that this paper can provide to the scientific community. The other three reviewers seemed to think the information was adequate, and had no issues with the length of the document. We will wait for the editor to decide on this point before moving ahead with the suggestion.
We sincerely thank the reviewer for this comment.
Reviewer 2 Report
Comments and Suggestions for AuthorsC1.
Line 35 – 38
I kindly ask authors to paraphrase the following sentence in the way that it is easily understandable by readers. In this way, it is rather confusing. Maybe it is better to make two sentences out of one.
The sentence is the following: „In practice, FLW indices have been further elaborated by the FAO where food loss involves the actions or decisions of suppliers and occurs from harvest (slaughter/catch) up to, but not including retail level whereas food waste, which spans both the retail and consumption levels, results from consumers’ behaviour, as well as retailers’ and food service providers’ actions or decisions [2, 3].
C2.
Line 52 – 53
It would be beneficial if authors could add sentence or two explaining terms animal by-products and secondary streams before following sentence where they are mentioned “Specifically, these secondary streams are excellent sources of protein (up to about 20%) which could sometimes be higher or comparable to that from other animal sources [5, 6].”.
I consider it is very important to explain to readers what these terms mean at the beginning of the manuscript.
C3.
Line 64 – 66
Please consider mentioning downsides of this derivatiosation of proteins from waste products („Redirecting proteins derived from food waste back into human food chain or into animal feed could enhance the efficiency of our global food system [9].“) like food safety and production costs.
C4.
Line 133 – 134
In the following statement „These include chickens, turkeys, ducks, geese and guinea fowl, among others. Of these poultry birds, chickens represent the vast majority at 63%, followed by ducks at 11%, geese at 9% and turkeys at 5% [32].“ Please indicate whether these values are for South Africa only or for a larger geographical area.
C5.
Line 157
Section 3.1. is well-written, clear, concise, easy to understand and writen in an interesting way for readers.
C6.
Line 389
When referring to conventional methods for collagen extraction from cattle tendons in the following sentence „Ran and Wang [121] compared the use of ultrasound pre-treatment of pepsin extraction with a conventional extraction method for the extraction of collagen from cattle tendons“, please specify the method briefly. Since you have mentioned many methods throughout the manuscript it would be easier for a reviewer to understand which specific method you have ment.
C7.
Line 421
Please check the font size in section 4.3. Microwave-assisted extraction
C8.
Line 568
Section 4.6. is well-written, concise and interesting from the reader point of view. However, it would be good if authors could add some drawbacks of the method. In addition, it would be beneficial to provide downsides of all methods mentioned in the manuscript, at the end of each section, if possible.
C9.
Line 791
In conclusion please specify which of the methods that you have described is most promising to be used commercially.
Author Response
Comments
C1.
Line 35 – 38
I kindly ask authors to paraphrase the following sentence in the way that it is easily understandable by readers. In this way, it is rather confusing. Maybe it is better to make two sentences out of one.
The sentence is the following: „In practice, FLW indices have been further elaborated by the FAO where food loss involves the actions or decisions of suppliers and occurs from harvest (slaughter/catch) up to, but not including retail level whereas food waste, which spans both the retail and consumption levels, results from consumers’ behaviour, as well as retailers’ and food service providers’ actions or decisions [2, 3].
Action: The sections has been broken down into three sentences and changes were made to ensure this section is clearer. We have highlighted this in red font. Thank you for the suggestion (L 36-40).
C2.
Line 52 – 53
It would be beneficial if authors could add sentence or two explaining terms animal by-products and secondary streams before following sentence where they are mentioned “Specifically, these secondary streams are excellent sources of protein (up to about 20%) which could sometimes be higher or comparable to that from other animal sources [5, 6].”.
I consider it is very important to explain to readers what these terms mean at the beginning of the manuscript.
Action: We sincerely appreciate the reviewer’s suggestion here. We totally agree with this comment. However, because subsequent section (section 2.0) has been dedicated to extensively describe this concept, we believe adding it here will only unnecessarily prolong an already long introduction. Please, see the definition of this concept in section 2 and in other sub-section in this section. Thank you.
C3.
Line 64 – 66
Please consider mentioning downsides of this derivatisation of proteins from waste products („Redirecting proteins derived from food waste back into human food chain or into animal feed could enhance the efficiency of our global food system [9].“) like food safety and production costs.
Action: We sincerely appreciate the reviewer’s comment here. We have now added a line to address this concern in this manuscript (L 66-67).
C4.
Line 133 – 134
In the following statement „These include chickens, turkeys, ducks, geese and guinea fowl, among others. Of these poultry birds, chickens represent the vast majority at 63%, followed by ducks at 11%, geese at 9% and turkeys at 5% [32].“ Please indicate whether these values are for South Africa only or for a larger geographical area.
Action: This point has been clarified, and the reference updated to avoid confusion. We appreciate the reviewer’s comment (L 143).
C5.
Line 157
Section 3.1. is well-written, clear, concise, easy to understand and written in an interesting way for readers.
Action: We appreciate the reviewer’s comment here. Thank you.
C6.
Line 389
When referring to conventional methods for collagen extraction from cattle tendons in the following sentence „Ran and Wang [121] compared the use of ultrasound pre-treatment of pepsin extraction with a conventional extraction method for the extraction of collagen from cattle tendons“, please specify the method briefly. Since you have mentioned many methods throughout the manuscript it would be easier for a reviewer to understand which specific method you have ment.
Action: We have added the specific conventional method in this sentence for clarification as suggested. Thank you for this comment (L 396).
C7.
Line 421
Please check the font size in section 4.3. Microwave-assisted extraction
Action: We have verified the font size in this section and have adjusted as needed. Thank you.
C8.
Line 568
Section 4.6. is well-written, concise and interesting from the reader point of view. However, it would be good if authors could add some drawbacks of the method. In addition, it would be beneficial to provide downsides of all methods mentioned in the manuscript, at the end of each section, if possible.
Action: We appreciate this comment from the reviewer. We consider that these points are already included at the end of each section addressing these protein extraction methods, whenever appropriate. The summarized Table 2 also add the merit and demerit of each of these extraction methods.
C9.
Line 791
In conclusion please specify which of the methods that you have described is most promising to be used commercially.
Action: We were hoping that this is the conclusion we will be able to arrive at as well. At the moment, we have however, been able to discuss this point within each section. Providing this recommendation as a general point is not possible at this time, as different research used different matrix, different extraction conditions among other varying parameters. However, this is the subject we are currently working on in our lab and we will be providing more information in this regard in due course. Thank you for your comment.
Reviewer 3 Report
Comments and Suggestions for Authors- Authors should include information regarding their information search strategy and the parameters they used to include or not include a reference in their document, in addition to establishing a justification for the use of references older than 10 years.
- Why is Figure 1 addressing potential reptilian and amphibian waste, but the text lacks any sections addressing these topics? Authors should supplement the information on reptilian and amphibian waste or remove it from the text.
- Authors should include examples of the solvents used in UAE, since the solvent also participates in the extraction, ultrasound is a support.
- Authors should mention which solvents are used in microwave-assisted extraction.
- Authors should specify what type of solvents are used to make PEF extraction feasible.
Author Response
Comments
- Authors should include information regarding their information search strategy and the parameters they used to include or not include a reference in their document, in addition to establishing a justification for the use of references older than 10 years.
Action: We have included a brief comment to this regard in the introductory part of this manuscript. We have previously omitted this considering the already voluminous nature of the manuscript. We believe that this information has less value compared to other important details added in this comprehensive review. We trust the editor will decide if this section is necessary (L 80-86).
- Why is Figure 1 addressing potential reptilian and amphibian waste, but the text lacks any sections addressing these topics? Authors should supplement the information on reptilian and amphibian waste or remove it from the text.
Action: Authors included reptilian and amphibian in the figure because the definition of meat includes tissue from these types of animals (as defined in line 97-100). This figure is only putting this definition into diagram format for easy comprehension. No publications were however, found reporting by-product utilization or valorization from either reptilian nor amphibian species. Therefore, this was not included in the review. If the editor considers we should remove them from the graph, even if they are part of the definition of ‘meat’, we can easily do so. Much appreciation to the reviewer for this comment.
- Authors should include examples of the solvents used in UAE, since the solvent also participates in the extraction, ultrasound is a support.
Action: Being considered a “green” extraction method, the ideal solvent for most UAE will be water except when it is combined with other substances like enzymes. A statement has been added to this section to reflect this. Thank you (L 392).
- Authors should mention which solvents are used in microwave-assisted extraction.
Action: As said previously, being considered a “green” extraction method, the solvent used for most MAE is water. This is reflected in most of the literature cited in this manuscript. Statement to reflect this has been added where necessary in the relevant sections. Thank you (L 443, 447).
- Authors should specify what type of solvents are used to make PEF extraction feasible.
Action: Authors appreciate this comment. In most cases with PEF, the most important factors are the electric field strength and the processing time, with less focus on the solvent which is usually water in most studies. This is what makes this method “green”. We have added a comment in this paper to reflect this. Thank you (L 482).
Reviewer 4 Report
Comments and Suggestions for AuthorsThe publication is very interesting and fits into a very important area of ​​research on reducing food losses. This is of significant importance for climate change. If food waste were reduced, world hunger would be eliminated and production could be reduced. Therefore, I consider the topic justified and worth describing. The tables and figures are appropriate and well thought out. However, Figure 4 is missing one more figure. I suggest adding another table showing data from the publication regarding the effectiveness of individual methods in protein extraction. It is also worth mentioning what happens to waste after extraction. It may also be worth mentioning the methods of obtaining collagen, which is a very popular dietary supplement today. And also describing the use of individual protein extracts. It is also worth mentioning that some animal offal is a very good source of many nutrients and their consumption can be popularized. This would also reduce their waste.
Author Response
Comments
The publication is very interesting and fits into a very important area of ​​research on reducing food losses. This is of significant importance for climate change. If food waste were reduced, world hunger would be eliminated and production could be reduced. Therefore, I consider the topic justified and worth describing. The tables and figures are appropriate and well thought out.
However, Figure 4 is missing one more figure.
Action: We do sincerely appreciate the reviewer’s comments here. We have now included the missing data in this figure. Thank you for pointing this out.
I suggest adding another table showing data from the publication regarding the effectiveness of individual methods in protein extraction. It is also worth mentioning what happens to waste after extraction.
Action: We understand the reviewer’s comment here. We believe that Table 2 has addressed this to a large extent. Considering the already lengthy and comprehensive nature of this paper, we believe this issue has been adequately addressed in the several paragraphs and in Table 2.
It may also be worth mentioning the methods of obtaining collagen, which is a very popular dietary supplement today.
Action: Authors appreciate the suggestion from the reviewer. Due to the extent of the topic and the amount of information already included in the review, we consider that focusing on protein extraction as a general concept is a more efficient approach. However, collagen extraction is included in several sections, as author’s acknowledge its current importance.
And also describing the use of individual protein extracts.
Action: Again, we appreciate the suggestion. Similar to the previous comment, potential uses are mentioned in different sections. However, a deeper dive on potential uses of the extracts could lead to a separate review in itself, and it is out of the scope of the current document.
It is also worth mentioning that some animal offal is a very good source of many nutrients and their consumption can be popularized. This would also reduce their waste.
Action: The reviewer is quite correct. With this in mind, we published a separate review in 2022. This point is already included in the document (reference 20, L113-115)
