Review Reports - Crack the Shell by Unlocking the Polyphenol Power of Hazelnut Waste with Ultrasound

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The potential use of agricultural byproducts as renewable resources is an important and pressing issue. The authors examine hazelnut shells as a potentially valuable source of bioactive polyphenolic compounds.
1. How was the moisture content of hazelnut kernels and shells determined, and how were changes in phenolic compound content monitored during the drying process?
2. What factors cause deviations in the integrated phenolic compound value from the actual content of similar substances determined chromatographically? What contribution do foreign substances, such as enzymes, vitamins, lignin, cellulose, and hemicellulose, make to the "determination of total polyphenolic compounds" determined using the Folin-Ciocalteu method?
3. How do the kernel lipid matrix, as well as fatty acids and trace elements, influence the accuracy of antioxidant activity determination using the ABTS, DPPH, and FRAP methods?
4. In Tables 1 and 2, the values for individual polyphenolic compounds and antioxidant capacity are given to the nearest thousandth, but the confidence intervals for the obtained values and the number of parallel measurements are not provided.
5. It is unclear from the data how the authors assessed the effect of extract dilution, which allows them to neutralize the influence of the matrix on the determination of total polyphenolic compounds using the Folin-Ciocalteu method. It would be interesting to compare the data obtained by varying the extract dilution and the sample weight of the kernels and shells.

Author Response

We thank the reviewer for their valuable comments. PLease see the attachment for a full point-by-point response.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a relevant topic within the scope of ChemEngineering, particularly regarding green extraction technologies and the valorization of agro-industrial by-products. The study is scientifically sound and presents valuable experimental data. Nevertheless, several aspects related to methodological clarity, data presentation, and contextualization within recent applied literature could be improved. To facilitate revisions, I have provided a detailed, structured table of specific comments and suggestions, which is attached as a supplementary PDF file. Addressing these points would significantly enhance the clarity, robustness, and overall impact of the manuscript.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English language is generally clear and understandable. However, minor grammatical issues, stylistic inconsistencies, and sentence structure refinements are present throughout the manuscript. It is recommended that the text be revised by a professional English editing service or a native English speaker to further improve clarity, fluency, and overall readability prior to publication.

Author Response

We thank the reviewer for their valuable comments. PLease see the attachment for a full point-by-point response.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript focuses on hazelnut shells, an agricultural waste, and uses ultrasonic-assisted extraction to extract polyphenolic compounds. It systematically investigates the effects of multiple factors such as ethanol concentration, amplitude, and time on the extraction effect. Not only were the total contents of polyphenols, flavonoids and non-flavonoids determined, but also 10 monomer phenolic substances were quantified by HPLC. The antioxidant activity was comprehensively evaluated by three methods: ABTS, DPPH and FRAP, and the correlation between them and the composition of polyphenols was analyzed. The manuscript also proposes calculation models for "theoretical polyphenol content" and "recyclable polyphenol quantity", providing certain quantitative basis for the assessment of industrialization potential. Finally, by comparing the two varieties' Rimski 'and' Istarski duguljasti ', it was found that the polyphenol content of the former was significantly higher, suggesting the importance of variety selection for the high-value utilization of waste.

Overall, this research topic is novel, the method is systematic, and the data is rich, possessing high application value and academic significance. But there are some problems which should be considered:

（1）It is recommended to increase the solvent concentration gradient (such as 30%, 50%, 70%, 90% ethanol); Set up pre-experiments with different solid-liquid ratios (such as 1:5, 1:10, 1:15); In "Materials and Methods", clearly specify the number of experimental repetitions (it is recommended that n≥3).

（2）It is suggested to deepen the discussion and mechanism analysis. For instance, add a section on "Variety Differences" and conduct an analysis in combination with the anatomical structure of the shell, lignin content, environmental factors, etc. Expand the "Ultrasonic Action Mechanism" section and introduce concepts such as cavitation intensity, energy density, and frequency effect; It is suggested that a paragraph titled "Comparison with Other Green Extraction Technologies" be added at the end of the discussion to enhance the technical foresight of the article.

（3）It is suggested that a subsection titled "Industrialization Potential and Challenges" be added to the conclusion section to appropriately discuss issues such as the cost, energy consumption, and solvent recovery of large-scale extraction.

Author Response

We thank the reviewer for their valuable comments. PLease see the attachment for a full point-by-point response.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have adequately addressed all comments raised during the previous review round.
The revisions improved the clarity of the manuscript, strengthened the methodological description, and enhanced the overall quality of the work.
I have no further comments and recommend acceptance of the manuscript in its current form.

Comments on the Quality of English Language

Author Response

Comment 1: The authors have adequately addressed all comments raised during the previous review round.
The revisions improved the clarity of the manuscript, strengthened the methodological description, and enhanced the overall quality of the work.
I have no further comments and recommend acceptance of the manuscript in its current form.

Response 1: We thank the reviewer for his comments.

Comment 2: The English language is generally clear and understandable. However, minor grammatical issues, stylistic inconsistencies, and sentence structure refinements are present throughout the manuscript. It is recommended that the text be revised by a professional English editing service or a native English speaker to further improve clarity, fluency, and overall readability prior to publication.

Response 2: Thank you for your comment. The language of the manuscript has now been double checked by an external language editing service.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have made the detailed supplementary revisions to the manuscript based on the reviewers' comments. However, the format of some references still needs to be carefully checked and modified in accordance with the requirements of the journal.

Author Response

Comment 1: The authors have made the detailed supplementary revisions to the manuscript based on the reviewers' comments. However, the format of some references still needs to be carefully checked and modified in accordance with the requirements of the journal.

Response 1: Thank you for your comment. We have double checked the references and corrected the format where needed.