Sustainable Ultrasound Assisted Extractions and Valorization of Coffee Silver Skin (CS)

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Specific comments are as follows:

First paragraph Page 1, Lines 34-38, Here author referred to the advantages of ultrasound use in the food industry including analysis and processing, and listed many of them………………….but reference [1] as author referred doesn’t include ultrasound……………please add the correct reference.

Page 2, Lines 71-74………. Why there is a reference [11-17] in the aim? No need for this added part and no references in the aim also.

Page 2, Chemicals: Why the author has deleted the manufacturer name and country that were written in the previous version? Please add the same paragraph as previously done.

2.2. Chemicals

               Following chemicals have been used in this research: Acetone (Lach-Ner, Neratovice, Czech Republic), Acetonitrile (Applichem, Darmstadt, Germany), Ammonium formate (GramMol, Zagreb Croatia), Argon, 99.9995% (Messer, Bad Soden am Taunus, Germany), Certified element reference material (CPAChem, Bogomilovo, Bulgaria), Distilled water, Nitric acid (Gram-Mol, Zagreb, Croatia), Helium, 6.0 (Messer, Bad Soden am Taunus, Germany), Methanol (GramMol, Zagreb, Croatia), Mixture of magnesium sulphate, sodium 85 chloride and citrate salts (Citrate-Kit-01, BEKOlut, Bruchmühlbach-Miesau, Germany), Mixture of magnesium sulphate salt, primary secondary amine and GCB (PSA-Kit-06, BEKOlut, Bruchmühlbach-Miesau, Germany), Sodium hydroxide (T.T.T., Sveta Nedelja, Croatia), Petrol Ether (Applichem, Chicago, USA), Sulfuric acid (Chemistry, Zagreb, Croatia), Hydrogen peroxide (Gram-Mol, Zagreb, Croatia).

Page 4, Line 145: Picture 1: CS samples with visible blue color ………………. Figure 1 not Picture and then renumber the later figures Figure 2, then 3….etc.

Page 4, Line 131: (Shortle et al.)……..delete because reference found at the end of the sentence [18]

Page 4, Lines 138-140:  Firstly, into a glass tube should pipette 0.1 mL of sample (extract), 7.9 mL of distilled water………....correct…….In a glass tube, 0.1 mL of extract, 7.9 mL of distilled water, and 0.5 mL of FCR (previously diluted 1: 2 into water) were added, then finally 20% sodium carbonate solution (Na2CO3) was added and vortexed.

How much mls of 20% sodium carbonate was added? Please mention.

Page 4, Line 142: The blind test is prepared…………correct to………… Negative control was setup

-  All subtitles need numbering according to journal guidelines.

- Also, references within the text need to be cited according to journal guidelines.

Page 4 continued in page 5: Title: Determination of protein concentration by the Lowry method and all subtitles’ paragraphs (determination, preparation, analysis, Derivatization and all the rest) need references…..Please add.

Page 5, Line 167: 10 mL of sample……..Did you mean extract?....please clarify.

Page 5, Line 174: 2 mL of reagent C-…………………what is this reagent (according to the manufacturer?)

Page 5, Line 178: A blind sample is prepared in the same way………………………..Negative control is prepared

In page 5: Determination of protein concentration by the Lowry method and Amino acid analyses were performed for all samples U1-U9….please clarify within the text.

Page 7, Line 242: results are presented in the form of chromatograms and tables…………………Please refer about chromatography in the materials part first.

I suggest again…… In all Tables: It will be good to order groups according to amplitude or time. The author writes sample numbers in a random way. I suggest being like the table below. ….This will be easier for readers to notices the difference between groups.

Page 8, Lines 251…………..is to monitor the change of the mentioned parameters every 15 seconds…………. This must be first mentioned in the materials part.

Page 9, Lines 282…………..Nzekoue et al. in their research have shown that water is the worst solvent for the extraction of polyphenols [22]………………………Mention in Discussion not results.

Page 9, Lines 294…………..system high-performance liquid chromatography with mass spectrometry (HPLC-MS/MS) and nuclear magnetic resonance (NMR)…………..Those analyses were done in the present study? If the author has used them, please mention them in the materials. If not, just recommend this later.

Page 11, Lines 357-359: Mention in Discussion not results. Also, resentence to be clearer.

In Results parts: no need to write in every title or subtitle “results of..”

HPLC chromatogram in the results…………..must refer first to this technique in the materials part and its setup conditions.

Page 13, Line 410: Therefore, U8 samples (100 % and 3 min) which showed the highest protein concentration and sample U6 (75 % and 3 min)……complete to the sentence.

Page 15-16 3.5. Environmental impact……………..This is discussion not results.

Page 17, Line 495: In presented results is shown that concentrations of amino acids in both samples differminimally……………correct sentence and words.

Page 17, Line 519: After protein extraction and separation, peptide analysis was performed with a mass spectrometer, the obtained results were identified using the UniProt database……..This technique was done in the present study or previously?

Page 17, from Line 521, the whole paragraph: The largest identified protein mass is 70.2 kDa. While the lowest mass is 15.7 kDa………….Those data are not found in the results. The author discusses missed results.

Discussion needs more effort, From Pages 17-18, Lines 533-560 Those are results only what is your explanation for those findings?

Discussion needs to be rewritten in an ordered manner and crosslinked with results.

In Abstract, where are the results in brief, most significant? Amino acids, proteins, most significant time and amplitude, etc.

The article needs more effort.

Best

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 2)

In this revised version, authors tried to improve their manuscript entitled "Sustainable ultrasound assisted extractions and valorization of coffee silver skin (CS)". Nevertheless, more improvements are necessary. Therefore, authors should proceed to a second revision of their manuscript according to the following comments and suggestions:

1) Sub session 2.2. Chemicals: It should be thoroughly revised (e.g., format instead of formate, etc.)

2) Sub-Sub sessions 2.3.2. Spectrophotometric determination of total polyphenols AND 2.3.3. Determination of protein concentration by the Lowry method: In both cases, authors should not try to "teach" the principles of their methods; the citation of the appropriate references are enough. Therefore, these principles should be eliminated from the manuscript in its next revision. Moreover, and in both cases I would suggest to authors to unify "Sample preparation" and "Determination procedure".

3) Tables 2, 3, 4, and 6: (a) It is much more enlightening to present tabulated results in single lines, (b) the number of used decimal digits depends on the accuracy of the used methodology (hardware and software), as well as on the expertise of the experimenter; thus, authors should use up to 2 decima digits in all cases. Authors should take into account that the use of different number of decimal digits among different measurements (and/or parameters) within an experimental procedure, is a serious mistake (e.g., in Table 4).

4) Figures 1 to 4: Authors should unify (in one figure) both response surfaces and contour diagrams.

5) Session 4. Discussion: The text should be thoroughly revised. For example, the second and third paragraphs should be elaborated accordingly by authors (minimize them as much as possible - refer the corresponding citation). Moreover, this kind of text should normally succeed the text of Discussion where the findings of the manuscript and their importance or potential applications were summarized and commended, etc.

  Overall: The revised version of this manuscript under consideration cannot be published in the journal Sustainability, before a major revision.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Third revision

Most of the previous comments are done but…..

A few specific comments are as follows:

 Page 1, Line 10: technologies . ……………….delete extra space.

Page 1, Line 13: The goal of this research was to isolate proteins and polyphenols using UAE extracted from CS and to employ spectrophotometry to determine the yields…………correct……………The goal of this research was to isolate proteins and polyphenols from CS using UAE and to employ spectrophotometry to determine the yields.

Page 1, Line 17: a conclusion can be drawn that………..correct to…………. it was reported that.

Page 1, Line 19: The most abundant amino acids in isolated proteins were defined as well………………….. OK please mention a few of those amino acids here.

Abstract needs to refer to your results (most important point), need your data.

Page 1, Line 37: extraction [1]..      delete extra full stop.

Page 4, Line 151: with blind test………………. Blind test is it the negative control? Please correct.

Negative controle is set up …………………….correct…………………. Negative control is set up

Page 5, Line 157: Environmental impact…… is it title or subtitle?…..number it.

Page 6, Line 184: reagent C ()- are pipetted…………correct………… reagent C (briefly defined below) are pipetted

Page 6, Line 192: Negative controle………………. Negative control

Page 17, Line 527: minutes..    delete extra full stop.

Page 18, Line 542-543: One of the main considerations that affect the outcome of the model is the way CS itself is considered………………………… not clear sentence, what do you mean? Please clarify.

Page 18, Lines 574-577: “The most abundant amino acids in isolated proteins are Asp, Glu, Pro, Gly and Ala. 574 Isolated proteins contain almost all essential amino acids. Analysis of the isolated proteins revealed an average protein mass of 15.7 kDa and 70.2 kDa. The protein with an average mass of 15.7 kDa contains a Barwin domain.”…………….It will be good to add such data (your data) to the results of the abstract. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 2)

In this second revised version, authors improved their manuscript. Nevertheless, still more improvements are necessary. Therefore, authors should proceed to a third (and final) revision of their manuscript according to the following comments and suggestions:

1)  Sub-Sub sessions 2.3.2.: The text "FCR is a mixture phospho- 136 tungstic and phosphomolybdic acids, this reacts with the phenoxide ion from the sample, 137 whereby the phenoxide ion is oxidized, and the FCR reagent is reduced to blue colored 138 tungsten and molybdenum oxides. The resulting staining intensity is measured at a wave- 139 length of 765 nm with a spectrophotometer (Lambda 25, UV / VIS spectrophotometer)", should be erased; the given reference [18] is enough.

2) Figures 1 to 4: Authors should unify (in one figure) both response surfaces and contour diagrams in the figures 1 to 4

3) In this second revised form, the session "Discussion" is more confusing than in the former revision. Therefore, authors should take into serious account this comment and present a new Discussion, seriously corecting Eglish sytax and grammar of the text.

Overall: The second revised version of this manuscript under consideration cannot be published in the journal Sustainability, before a third revision, according to the abovementioned comments and suggestions.

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report (Previous Reviewer 2)

It seems to me that authors seriously tried and prepared a new version of their manuscript, by based, and by conformed to all reviewers' comment and suggestions; in my opinion they succeeded.

  Therefore, I can reccomend the publication of the present version of the manuscript under consideration in the Journal Sustainability.

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

Specific comments are as follows:

First paragraph Page 1, Lines 34-38, Here author referred to the advantages of ultrasound use in the food industry including analysis and processing, and listed many of them………………….but reference [1] as author referred doesn’t include ultrasound……………please correct and add more updated references about those listed points.

Page 2, Line 45…………..processes extractions……correct………..extraction processes.

Page 2, Line 47…………..solvent content……….What is the mean of solvent content? Did you mean a reduction in the amount of used solvent in the extraction process?...........please clarify.

Page 2, Line 51…………. (UN, 2015)………..use references within the whole text according to the journal guidelines.

Page 2, Line 54…………. UN……define first time before abbreviation.

Page 2, Line 59…………. for academia……correct…….for researchers.

Page 2, Line 60………. CSS………… define first time before abbreviation.

Page 2, Line 63………. non-themr4al………..correct.

Page 2, Line 64………. Zhang et. al (2020) analyzed utilization in producing polyphenols-rich extracts from CSS by using ultrasound extractions [10]……….rewrite the sentence to be clear and write references within the text according to the guidelines…. Zhang et. al [10]… 

Page 2, Line 69………. Why there is a reference [11] in the aim? The aim is for your work that is not duplicated.

Page 2, Line 72………. i.e., CS samples……rewrite…. After coffee roasting, CS by-products have been used in the present research.

It will be good to figure out a scheme for collected samples under subtitle 2.1. Samples (Page 2).

In Table 1, Page 3, It will be good to order groups according to amplitude or time. The author writes sample numbers in a random way. I suggest being like the table below.

Page 4, Line 140………. Pipette 0.1 mL, 7.9 mL of distilled water……. 0.1 or 7.9 mL of distilled water?

Page 4, Line 141………. Stir and add 1.5 mL of 20% strength sodium…………..correct …….. Stir and 1.5 mL

What is strength?

Page 4, Line 142…………The contents of the tube are well again stirred on the Vortex device…………simply write in the previous sentence …………and then vortexed.

2.3.3. Statistical analysis……….Page 4

Please combine statistical analysis found in page 3 and page 4 under this subtitle.

Paragraphs in Page 5, Lines 177-188…………duplication that is mentioned in materials before.

Page 5, Lines 189&191…………UAE execution? Please correct.

Where is the statistical analysis using ANOVA in tables and results? Author mentioned it in materials.

Page 6, Lines 196…………..is to monitor the change of the mentioned parameters every 15 seconds…………. This must be first mentioned in materials part.

Where are the comparison differences between different groups?

standard error is very low according to values……Is it right? Please check (Table 2 & 3).

Page 7, Lines 227…………..Research has shown that water is the worst solvent for the extraction of polyphenols (Nzekoue et al., 2020) [16]………………not referred in results but must be mentioned in discussion.

3.4. Environmental impact (subtitle) in Page 8, where is the results? Just table and the paragraphs lines 264-277 discussion and not results. Please rewrite in clear way and then add in discussion part to discuss your results.

Page 7, Lines 285……………….The statistical analysis of the parameters revealed that???? Where is the statistical analysis? Where is (p<0.05)?

There is no discussion of results, it is as the results.

In conclusion part……….

Page 10, Lines 332-335……..The most abundant amino acids in isolated proteins are Asp, Glu, Pro, Gly and Ala. 332 Isolated proteins contain almost all essential amino acids. Analysis of the isolated proteins 333 revealed an average protein mass of 15.7 kDa and 70.2 kDa. The protein with an average 334 mass of 15.7 kDa contains a Barwin domain.

These data are not found in results. Where are those isolated proteins and their molecular weight that mentioned here? Not found within the whole article.

Page 10, Lines 336-341…………the same paragraph as the last one in discussion……duplication.

Abstract needs to be more concise, where is the results in brief, most significant?

Article needs more effort, more updated references.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors of the manuscript entitled "Impact of non-thermal techniques in the processing of coffee silver skin (CS)" report interesting data. On the other hand, the manuscript cannot be published in the present version, according to the following comments:

1) The text is not well followed, is difficult to be understood, and some parts are incomprehensible. The manuscript needs of a thorough revision.

2) Section 2.2. Chemicals (lines 80-90): Authors should shorten this part of text (e.g. it is not informative to describe all the regents in details).

3) Section  2.3.2. [Principle of determination] (lines 125-135): I would suggest to authors, to eliminate the "Principle of determination"; it is well known.

4) Section 2.3.3. Statistical analysis (lines 169-170): I think that Microsoft Office Excel is a very weak statistical pack, and authors should use a more confident statistical tool when preparing their revision.

5) TABLES 2, 3, and 4: Authors should rewrite their results depicted in these Tables by using ONLY TWO decimal digits; two decimal digits are enough according to the followed methodologies.

6) Section Conclusions (line 332): Authors write in the text "The most abundant amino acids in isolated proteins are Asp, Glu, Pro, Gly and Ala". However, there are not relevant methodologies and results in the text. Therefore, authors shoud either describe their methods and the corresponding results, or the delere the aforementioned text in quotation marks.

7) Overall: The presnt version of this manuscript under consideration cannot be published before a major revision. I suggest the rejection of this manuscript; Editors may ecourage authors to reconsider and revise their manuscript according to the reviwers' comments, and resubmit it for evaluation.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Line 9: Edit the abstract to visibly understand the objective of the study.

Line 29-43: Very vague, doesn’t add considerable value. Rewrite and limit this to 10 lines.

Line 100: The idea and practical need of UAE versus other techniques weren’t portrayed well

Line 54-65: Vague, be more specific and only include relevant information that adds to your present research.

Line 66: Please clearly present the hypothesis and contribution of your study in the introduction section. Did any researchers previously use UAE to isolate proteins and polyphenols from coffee silver skin.

Line 69: Why is coffee silver skin abbreviated both as CS and CSS. Check for consistency

Line 71: Poor information on sample collection, storage, etc.

Line 99: This opening sentence is unnecessary.

Line 100: Manufacturer info on the Ultrasonic processor is missing

Line 102: Why was a control not considered for the set of experiments to compare with

Line 108: Why was the goal to design experiments to determine the statistical impact of each factor, how were the parameters selected and optimized

Line 115: Why were the RSM results not discussed in the manuscript

Line 125: Rewrite the method for better clarity and include suitable references

Line 171: Lacks scientific writing clarity, rewrite  

Line 191: Why do you put “comma” while representing temperatures and other values, it has to be a decimal. 

Line 200: What’s SPK

Line 194-228: Very poor scientific writing style

Line 232: Why does the authors keep using comma instead of decimal

Line 280-321: Extremely poor discussion 

Line 323: Include a comment indicating the potential use of this research at industrial level and its “real” significance

Author Response

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Reviewer 4 Report

The manuscript is not good enough to be accepted by the journal. Ultrasound-assisted extraction is not a “new innovative techniques” as claimed by the authors, actually is a quite common and old method to extract compounds. All the results in this manuscript could be shown in one table, the manuscript did not show sufficient data. For Response Surface Methodology, we usually conduct equation fitting to find a really optimized parameters combination, however, the author did not do that. The method for quantifying protein was missing, and the author suddenly told readers the ratio of amino acids and average protein mass in the discussion section without showing any information in the results and discussion sections, which cause severe chaos to the structure of manuscript. Besides, the environmental impact is an important part in the study, however, the manuscript did not introduce in detail how the evaluation process was conducted. It looks this is not a complete manuscript.

Author Response

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