Green Valorization of Parapenaeus longirostris By-Products Through Ultrasound-Assisted Extraction of Astaxanthin with Extra Virgin Olive Oil: Application in Functional Trahanas with Enhanced Stability and Consumer Acceptability

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

After conducting a thorough re-examination of the manuscript, it has been noted that the authors have indeed revised many descriptions and seriously considered the reviewers’ suggestions, leading to certain improvements in the overall research. However, it must be acknowledged that the study remains somewhat superficial in nature. While it may serve as a reference material, the limited amount of data and the lack of systematic presentation of the results contribute to the paper being only of average quality overall.

Comments on the Quality of English Language

The manuscript presents its findings clearly, but to enhance its impact, the logical structure and depth of analysis require attention. Strengthening the connections between sections and providing more detailed explanations for key observations would create a more cohesive and persuasive narrative. A revision focused on refining the argumentation flow is recommended.

Author Response

Comments and Suggestions for Authors

After conducting a thorough re-examination of the manuscript, it has been noted that the authors have indeed revised many descriptions and seriously considered the reviewers’ suggestions, leading to certain improvements in the overall research. However, it must be acknowledged that the study remains somewhat superficial in nature. While it may serve as a reference material, the limited amount of data and the lack of systematic presentation of the results contribute to the paper being only of average quality overall.

Comments on the Quality of English Language

The manuscript presents its findings clearly, but to enhance its impact, the logical structure and depth of analysis require attention. Strengthening the connections between sections and providing more detailed explanations for key observations would create a more cohesive and persuasive narrative. A revision focused on refining the argumentation flow is recommended.

Answer

We thank the reviewer for the comments. English Editing has been requested for the manuscript.

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

Dear authors,

I send you my warmest regards. Furthermore, I would like to thank you for taking into account the observations and suggestions.

I believe the work has been significantly improved. I would just like to make a few minor observations: 1) What do lines 377-378 indicate or correspond to?; 2) Please verify the font type and size in the figure and table captions; 3) In line 559 (3.8 Color determination), please verify the language; 4) Figure 5 has been added. However, I suggest making some aesthetic modifications for better readability (removing the title in the figure (Hedonic test)).

That's all for now.

Author Response

Dear authors,

I send you my warmest regards. Furthermore, I would like to thank you for taking into account the observations and suggestions.

I believe the work has been significantly improved. I would just like to make a few minor observations: 1) What do lines 377-378 indicate or correspond to?;

2) Please verify the font type and size in the figure and table captions; 3) In line 559 (3.8 Color determination), please verify the language;

4) Figure 5 has been added. However, I suggest making some aesthetic modifications for better readability (removing the title in the figure (Hedonic test)).

That's all for now.

Answer

We thank the reviewer for the useful comments.

1) Lines 377-378: The references are now deleted.

2) The type and size of figures and tables captions are verified

3) Line 559: This text was inserted automatically and now it is deleted.

4) Figure 5 (Figure 4 in the revised MS): the title was removed

Reviewer 3 Report (Previous Reviewer 4)

Comments and Suggestions for Authors

Most issues raised in the first round have been adequately addressed and justified by the authors. However, the second point regarding accelerated storage remains only partially validated. While the cited studies support the general use of accelerated storage tests, they do not directly support the specific equivalence of 6 days at 65 °C to three months at ambient conditions for astaxanthin in a cereal matrix. Please provide either a citation that specifically supports this equivalence or an Arrhenius-based calculation demonstrating it.

Author Response

Most issues raised in the first round have been adequately addressed and justified by the authors. However, the second point regarding accelerated storage remains only partially validated. While the cited studies support the general use of accelerated storage tests, they do not directly support the specific equivalence of 6 days at 65 °C to three months at ambient conditions for astaxanthin in a cereal matrix. Please provide either a citation that specifically supports this equivalence or an Arrhenius-based calculation demonstrating it.

Answer

We thank the reviewer for this comment and agree that a fixed equivalence between accelerated and ambient storage conditions cannot be assumed without kinetic validation. In the revised manuscript (highlighted text in green color), accelerated storage at 65 °C is interpreted through first-order degradation kinetics combined with Arrhenius-based extrapolation rather than an empirical time conversion.

Specifically, degradation rate constants obtained under accelerated conditions were related to ambient temperature using literature-derived activation energy values from structurally comparable dry, encapsulated systems. Time equivalence between 65 °C and 25 °C was then derived by equating the kinetic terms of the two conditions, ensuring that the accelerated storage interpretation is fully grounded in kinetic theory.

 

Reviewer 4 Report (Previous Reviewer 5)

Comments and Suggestions for Authors

Dear authors,

 

I would like to thank you again for this study and for your answers to my questions. It is all good for me.

 

Kind regards

 

Author Response

Comments and Suggestions for Authors

Dear authors,

I would like to thank you again for this study and for your answers to my questions. It is all good for me.

Answer

We thank the Reviewer for the initial comments that contributed to the improvement of our manuscript.

Reviewer 5 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

The study “Green Valorization of Penaeus longirostris By-Products through Ultrasound-Assisted Extraction of Astaxanthin with Extra Virgin Olive Oil: Toward Functional Trahanas” is highly relevant and demonstrates clear innovative value. The authors have adequately addressed most of the previously raised concerns, and the scientific soundness of the manuscript has improved accordingly. Nevertheless, several minor issues still require clarification before the manuscript can be deemed suitable for publication.

First, the materials used in the study remain insufficiently characterized. The sources and origin of the raw materials—including the olive oil and other ingredients listed in Section 2.1—are not clearly specified. Providing this information is essential to ensure transparency, traceability, and reproducibility.

Second, the quality and scientific relevance of Figure 3 raise concerns. Its resolution and visual presentation do not meet the expected standards for a scientific publication, and its contribution to the interpretation of the results appears limited. The authors should either significantly improve this figure or justify its inclusion in the manuscript.

If the authors address these remaining minor issues, the manuscript would be suitable for publication.

Author Response

Comments and Suggestions for Authors

The study “Green Valorization of Penaeus longirostris By-Products through Ultrasound-Assisted Extraction of Astaxanthin with Extra Virgin Olive Oil: Toward Functional Trahanas” is highly relevant and demonstrates clear innovative value. The authors have adequately addressed most of the previously raised concerns, and the scientific soundness of the manuscript has improved accordingly. Nevertheless, several minor issues still require clarification before the manuscript can be deemed suitable for publication.

First, the materials used in the study remain insufficiently characterized. The sources and origin of the raw materials—including the olive oil and other ingredients listed in Section 2.1—are not clearly specified. Providing this information is essential to ensure transparency, traceability, and reproducibility.

Second, the quality and scientific relevance of Figure 3 raise concerns. Its resolution and visual presentation do not meet the expected standards for a scientific publication, and its contribution to the interpretation of the results appears limited. The authors should either significantly improve this figure or justify its inclusion in the manuscript.

If the authors address these remaining minor issues, the manuscript would be suitable for publication.

Answer

We thank the reviewer for this insightful comment. In response, we have significantly revised Section 2.1 (highlighted text in yellow color) to include detailed information on the origin and characteristics of raw materials used in the study. These additions improve the transparency and reproducibility of the study by documenting the raw material composition and origin more rigorously.

Regarding fig. 3, Figure editing has been requested for the MS.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. What is the detection limit for astaxanthin, and do the analyzed data hold research significance?

2. Given the notably low content of astaxanthin, is further research warranted? Has it already achieved mass production? What is the rationale for studying astaxanthin?

3. The color evaluation in the sensory assessment lacks comparative value, as the data are largely consistent. Could the results be stated directly—i.e., that there was no observable color change?

4. The research content appears relatively simplistic, lacking in-depth investigation and practical applicability.

5. The gradient design in the response surface methodology requires further optimization, as the current results may not represent the optimal combination.

6. Does the use of extra virgin olive oil offer significant advantages over other extraction solvents, or is it merely associated with higher costs?

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript “Green Valorization of Penaeus longirostris By-Products through Ultrasound-Assisted Extraction of Astaxanthin with Extra Virgin Olive Oil: Toward Functional Trahanas” addresses a relevant topic and has the potential to attract readers’ interest. However, there are several issues that need to be corrected, which I have listed below. These points must be addressed before the manuscript can be considered for publication.

1.The materials used in the study must be properly characterized. In particular, the basic nutritional data of olive oil and other products listed in Section 2.1 should be clearly provided. This information is essential to ensure the reliability and reproducibility of the study results. It is recommended to include these data in the main text, and if the amount of information is too extensive, they can be added as supplementary material.

2. The data presented in Table 1 are repeated twice in the methodology section (lines 140–143 and 152–155). Please either remove the table or restructure the methodology to avoid redundancy.

3.Section 2.9 contains excessive information. It is not necessary to provide detailed descriptions of the standards, as these are routine analyses. Indicating the standard code alone is sufficient.

4.Please provide the predicted R² and adjusted R² coefficients for the optimization results.

5.Table 2 ("Coded levels") would be clearer if the actual values for Extraction Time, Liquid–Solid Ratio, and Ultrasound Amplitude were provided directly. The current duplication and lack of systematic presentation of the data make the manuscript more difficult to follow.

6.Sections 3.1.1–3.1.3 lack systematic structure and contain excessive information. Please shorten the text and reduce redundancy. The content could be streamlined by integrating it with Section 3.1.5.

7.Table 9 does not provide meaningful information and I recommend removing it.

8.The data in Table 10 and Figure 3 are duplicated. Please keep only one version to avoid redundancy.

9.Line 709: Why did a significant difference occur? How can this be justified or explained based on the data?

10.The manuscript does not specify how many participants were involved in the sensory analysis, nor does it provide information on their gender and age distribution. Please include these details in the methodology section.

11.In Figure 5, the parameters of the Y-axis are not indicated. In addition, please explain why the interval 0–6 was chosen for the graph, while the methodology specifies a range of 0–7.

12. The current “Conclusions” section mainly reiterates the discussion of results rather than presenting clear conclusions. A main conclusion is missing, namely what this study has actually confirmed. The statement that ultrasound is a sustainable technology is questionable. If such a claim is made, different extraction processes should be compared. On what criteria is ultrasound considered a sustainable solution, and was this demonstrated in your study?

 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

I send you my cordial greetings after thoroughly reviewing the work entitled "Ecological valorization of Penaeus longirostris by-products through ultrasound-assisted astaxanthin extraction with extra virgin olive oil: Towards a functional Trahanas." I believe the work can be published; however, some modifications are necessary. The observations, suggestions, or questions detailed below are intended to make the research more understandable and attractive to the reader.

Keywords: It is suggested to reduce the number of keywords and use words other than those in the title. Introduction: Reference (5) is widely used; a more exhaustive review with a greater number of references is suggested. In addition, it is recommended to consult and reference the original works. Please review the full document.

Materials and methods: This section details the experimental phase, including the necessary controls. Remember that an important characteristic of research is repeatability. On the other hand, although much of the methodological section is unique (by some authors), I personally consider detailing this section. Also, consider removing some paragraphs that do not contribute anything to this section. Please revise in the entire document.

Results and Discussion. In general, this section must follow the following order:

1) Description of the results with the level of detail that the authors consider necessary, as long as they are objective (avoid texts that intend to favor the results of the investigation); 2) Discuss the most important causes of the results (using references that help clarify the results); 3) Compare the results with similar investigations (objectively). It is suggested to avoid paragraphs that do not contribute anything to the section (description, discussion and/or description). In general, at the end of each sub-theme of this section, a paragraph with lo que parecen ser conclusionsos is included (please delete). Some sections only contain a description of the results. I suggest that the authors make a detailed review of sections 3.8 and 3.11.

Conclusions. Revise todo el documento. It is suggested to extract very specific conclusions according to the scope of the objectives, as well as the most outstanding results. Referenced. In general, consider that the quantity is adequate. Please refer to reference 21 (revise in the entire document)

Comments for author File: Comments.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This manuscript provides a moderate novelty. While ultrasound-assisted extraction of astaxanthin from crustacean by-products is already well established, the use of extra-virgin olive oil as a green solvent, combined with its incorporation into a traditional cereal-based product (trahanas), represents an innovative applied approach. The strength lies in validating both nutritional stability and consumer acceptability, which increases the practical relevance.
However, the manuscript presents several critical weaknesses. First, the reported extraction time of 228 min appears unusually long for UAE; the authors should justify why such an extended time is still considered "green" and energy-efficient. Second, the claim of over 90% retention over three months seems overstated, particularly since essential details on storage conditions (light, temperature control) are missing. Third, there are taxonomic inaccuracies: the correct species name is Parapenaeus longirostris (deep-water rose shrimp), not Penaeus longirostris nor simply “shrimp”.

For these reasons, I recommend rejection in its current form. Nevertheless, I provide below a series of recommendations that, if addressed, could substantially improve the quality of the work.

 

Title:

It feels like just another extraction study; the novelty of the study is not highlighted in the title, which includes functional trahanas, stability tests, sensory analysis, and omega-3 enrichment. I propose replacing "toward functional Trahanas" with "Its application in functional trahanas with enhanced stability and consumer acceptability."

 

Abstract:

The abstract sometimes overstates the novelty of the extraction method. Ultrasound-assisted extraction of astaxanthin is well established. The use of food-grade oils as green solvents has also been previously reported. The true novelty of this work lies in applying EVOO-based extracts for trahanas fortification. This demonstrates nutritional stability, omega-3 incorporation, and sensory acceptability. The authors may consider rephrasing conclusions to highlight these applied contributions rather than presenting the extraction method as highly novel.

The keywords cover all the main aspects of the study. They could be improved by including terms that reflect the novelty and nutritional significance, such as "functional food," "omega-3," or "optimization." This would enhance indexing and discoverability.

 

Introduction:

This section is well-organized, providing a logical background from astaxanthin's health benefits to the challenges of conventional extraction, the potential of green solvents, and the rationale for using trahanas as a functional food matrix.

However, some claims should clarify the species or context:

Lines 63-65: The supercritical CO2 extraction (SFE) is mentioned but not linked clearly to shrimp by-products, which makes the question of why it its irrelevant if didn't linked clearly with the species studied.

Line 73: Statement like astaxanthin dispersed in olive oil accumulates more in plasma and liver" is correct, but should indicate the species to avoid overgeneralization.

Lines 44, 51, 57, 63, 69, 71, 72, 75, 76, 83: those sentences need a reference.

 

Materials and Methods:

Most methods are detailed, but there are some experiments that are not robust:

-2.2 and 2.3: Storage conditions of raw samples and extracts are missing, and the ultrasound mechanism is overly detailed, and there is no indication of stable parameters like pH, temperature, and cycle used

-2.5: Photometric determination is acceptable but relatively weak compared to HPLC and limits accuracy and specificity because of the risk of interference from other carotenoids.

-2.14: Sensory evaluation, the number of participants is missing.

 

Results and Discussion:

This section is clear and detailed, but presents limitations:

Table 6: Storage stability was assessed using accelerated conditions at 65 °C. Extrapolating to real-time storage at room temperature is not justified.  

Table 7: The sharp reduction in protein content of enriched trahanas is not adequately explained, as it undermines the robustness of the nutritional value.

Table 8: add the abbreviations' meaning.

 

Conclusion:

The section is overly detailed for a conclusion; shorten it to 3 focused paragraphs.

 

References:

The references cover all aspects and are up to date with the research, but still some mistakes need to be corrected, like the italicization of species names in references 6, 18, 19, 28, and 33.

Comments on the Quality of English Language

Language and grammar issues redundancy and wordiness, sentences are long and clunky.

Reviewer 5 Report

Comments and Suggestions for Authors

Dear,

 

First, I would like to thank the authors for this original work. Please find below few comments:

Line 138: How did you choose these levels?  

Line 303 : what is the statistical analysis of these results? for (0,0,0) repetitions for example. Is there a significant difference between the sample 3 and 14?   

Line 311: your argument about the relation (extraction yield vs time) needs more investigation. What about the extraction temperature during the extraction?

Line 362 : all parameters are connected. I don’t think that you can conclude that increasing solvent/solid ratio would increase the yied under your experiments. What do you think will be the result for a ratio of 120 or more?

Line 368 : please re-write: increased from 42 to 77.12.

Line 462 : based on this table, does the extraction time have no effect of the yield?

 

I really appreciated the important realized work.

 

Thanks