Improved Antioxidant Capacity by Block Cryoconcentration of Opuntia ficus-indica L. Mill (Green and Red) Juice

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The aim of this study was to employ cryoconcentration facilitated by centrifugation to extract prickly pear (Opuntia ficus-indica L. Mill) concentrate from two ecotypes (green and red) and assess their effects on the polyphenol profile and betalains. The submitted manuscript, although quite short and limited in the terms of amount of results, is in my opinion suitable for AppliedChem. However, it should be also revised before proceeding further.

Line 16, an alternative to what? I would expect this sentence to go like this: “An alternative to …. is the use of cryoconcentration for …. “.

Line 21, please delete “process”

Line 25, “high” or “higher”?

Line 32, “T” should be removed

Line 35, the figure presenting the photo of prickly pear should be included in the introduction

Lines 42-46, those information need references

Line 59, here, the aim of the study should be clearly stated

Lines 144-146, what do you mean by that? Was this purity of ice somehow assessed? This should be elaborated more.

Table 4, how can the R for betanin/ABTS be exactly 1.0? This should be commented on.

Table 2, % of citric acid, it should be 0.05, not .05. Please correct the other ones too.

How many repetitions were performed for each experiment?

The uncertainties and statistical analysis of pH (Table 2) is quite strange for me. How can the uncertainty be exactly 0? I suppose the same values have been obtained among the different repetitions. If it was so, how can you compare those values in terms of statistical analysis using ANOVA? And how can there be no different between 4.9 and 5.0 with a difference between 5.0 ad 5.1?

Author Response

Please see attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The present research evaluates the effectivines of cryoconcentration of the juice of Opuntia.

The abstract could be improved adding more results.

The introduction lacks of references, and could be completed with more data about the importance of the antixidants present in the Opuntia juice and why we would like to concentrate them. Then the research question should be clearly stated showing the novelty compared to the previous researches.

In the material and methods there are important lacks, the most important are about the origin (variety, maturity status, how long samples have been harvested, how they were stored), how many fruits you took per type... this is important in order to stablish the pertinent analysis and comparison between the two types, we cannot be sure with the information given, that the differences obtained are not related to a difference of maturity status of the fruits, or a delay in the harvest time, so any comparison at these level is not possible without more data.

The methods employed should be described, not just citing the reference.

The results are not well described and english is confusing, tables should be completed with the acronyms.

The discussion is quite complete, but lacks some references and is difficult to compare something that is not comparable.

Conclusions could be improved as there are more a resume of the results.

More details in the document attached

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Many paragraphs should be reviewed, sentences are too long, difficult to understand, and verbs are missing

Author Response

The present research evaluates the effectivines of cryoconcentration of the juice of Opuntia.

The abstract could be improved adding more results.

R= Tha abstract was improved including more results

The introduction lacks of references, and could be completed with more data about the importance of the antixidants present in the Opuntia juice and why we would like to concentrate them. Then the research question should be clearly stated showing the novelty compared to the previous researches.

R= The introduction was improved, including proper cites, also the objective was rewritten.

In the material and methods there are important lacks, the most important are about the origin (variety, maturity status, how long samples have been harvested, how they were stored), how many fruits you took per type... this is important in order to stablish the pertinent analysis and comparison between the two types, we cannot be sure with the information given, that the differences obtained are not related to a difference of maturity status of the fruits, or a delay in the harvest time, so any comparison at these level is not possible without more data.

R= More details about origin, methods were introduced in the revised manuscript

The methods employed should be described, not just citing the reference.

R= It was done in the revised manuscript

The results are not well described and english is confusing, tables should be completed with the acronyms.

R= The English was polished by English teacher

The discussion is quite complete, but lacks some references and is difficult to compare something that is not comparable.

R= More references were included

Conclusions could be improved as there are more a resume of the results.

R= Conclusions were re-written in the revised document

More details in the document attached

R= Repply to all comments were done in the document attached

Thank you very much for your comments, suggestions and opinions

On the behalf of all authors

Dr José Alberto Gallegos-Infante

Please see the attachment for all answers

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Marquez-Montes et al. have aimed to use cryoconcentration assisted by centrifugation to obtain prickly pear concentrate from two ecotypes (green and red) for evaluation of their impact on polyphenolic profile and antioxidant activity. Although some interesting data have been obtained, the following points need to be addressed for a possible publication in AppliedChem:

General

1.        All abbreviations should be explained in the full form at the first instance and thereafter abbreviated.

2.        All abbreviations in each table and figure should be explained in full form in the respective table footnotes and figure captions.

Abstract

3.        Some important quantitative data should be included.

Keywords

4.        “antioxidant activity” and “cryoconcentration” should be added.

Introduction

5.        Some more background information related to this study should be included.

6.        The introduction should end with a formal description of the objectives.

Materials and methods

7.        All the subheadings should be numbered like 2.1., 2.2.,..so on

8.        Several one or two-sentence paragraphs should be combined into several large paragraphs.

9.        The authors should ensure inclusion of at least one reference citation for each method described.

10.     This section looks disordered and should be arranged and formatted properly.

11.     The number of replicates should be included in data analysis section.

Results and discussion

12.     All the tables should be arranged and formatted for clarity and legibility.

13.     Having obtained many data from various parameters, the authors should run principal component analysis (PCA) to establish possible correlations between parameters.

14.     Several one or two-sentence paragraphs should be combined into several large paragraphs.

Conclusion

15.     The limitation of this study and future perspectives should be added.

References

16.     Very old references should be replaced with new ones.

Author Response

Please see attachment

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The objective of the present work was to use cryoconcentration assisted by centrifugation to obtain prickly pear (Opuntia ficus-indica L. Mill) concentrate from two ecotypes (green and red) and evaluate their impact on polyphenols profile and betalains. An important increase in betanin content and high antioxidant activity was observed for cryoconcentrated red prickly pear juice. The authors underlined that the use of cryoconcentration technology to process prickly pear juice has a high potential to process it, without damage to bioactives.

Some suggestions:

1.line 42 – please clarify what do you mean by “various food products”.

2. lines 55-59 - please reformulate the phrase.

3. lines 70-71 – please specify if you picked the fruits yourself or you bought them (from where)

4. lines 75-76, you wrote: “The juice was obtained using a mechanical pulper, filtered, frozen at -20 °C and stored until use.” Give please details concerning the storage and stability.

5. page 3 – give please details concerning the determination of ° Bx and for the methods used to determine the reducing sugars, total phenols, flavonoids, betalains and antioxidant activity (FRAP, ABTS, ORAC)

6. All the abbreviations must be explained. 7. Please add which are the limitations of the study.

Author Response

Please see attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The Authors have revised and improved their work, current version can be accepted for publication.

Author Response

Thank you very much for review

Regards

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have provided a nice correction of the document.

The main improvements have been performed in the abstract, the research question and the material and methods.

As you can not give more information on the vegetal material you have at least you need to improve the discussion, including a section saying which impact on the growing conditons, harvest time and storate duration on your molecules of interest, to identify that you couln't catch this variability on your analysis.

In the conclusion there are still many results and less conclusion than expected.

There are other minor things to review, please see attached

Comments for author File: Comments.pdf

Author Response

Answer to reviewer 2

The authors have provided a nice correction of the document.

R= Thank you very much for your comments

The main improvements have been performed in the abstract, the research question and the material and methods.

R= Thank you very much for your comments

As you can not give more information on the vegetal material you have at least you need to improve the discussion, including a section saying which impact on the growing conditons, harvest time and storate duration on your molecules of interest, to identify that you couln't catch this variability on your analysis.

R=Thank you very much for the comments, they were included in the revised manuscript (end of discussion) as follows:

It is important to note, that the amount of bioactives as betalains, flavonoids, phenolic acids are influenced by several environmental conditions that do not control in the present experiment, thus, is important to develop experiments with control of harvest, growing conditions, to evaluate the effect of these conditions on the quality and quantity of these bioactives in prickly pear cultivars.

In the conclusion there are still many results and less conclusion than expected.

R= It was corrected as follows:

An important increase on betanin content was observed for cryoconcentrated red prickly pear juice, and indicaxanthin showed an increase, The increase of betalains was not related concentration factor. High values of total polyphenolic content (TPC), total flavonoid content (TFC) and high antioxidant activity were observed for cryoconcentrated prickly pear juices (red and green). As expected high amount of betalins was observed in red prickly pear juices, hower, green prickly pear juice showed presence of them. Betalains showed high correlation with ABTS antioxidant results, and TPC, showed high correlation with ORAC results. The use of cryoconcentration technology to process prickly pear juice have a high potential to processing it, without damage to bioactives (flavonoids, betalains).

There are other minor things to review, please see attached

R= Thank you very much, they were corrected in the revised manuscript, also, please see the pdf attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have satisfactorily addressed all the comments raised by reviewers and substantially improved the overall quality of this article. Therefore I recommend accepting this article for publication in AppliedChem.

Author Response

Thank you very much for the comments

Regards

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have done great efforts improving the manuscript and adding what was requested last time.

Now the discussion is nearly ready, but some english errors should be corrected, please check the last paragraphes for english coherence and add a reference if it exist on the environmental variability of compounds of opuntia fruits. See attached where.

Comments for author File: Comments.pdf

Author Response

The authors have done great efforts improving the manuscript and adding what was requested last time.

R= Thank you very much for your questions and comments

Now the discussion is nearly ready, but some english errors should be corrected, please check the last paragraphes for english coherence and add a reference if it exist on the environmental variability of compounds of opuntia fruits. See attached where.

R= Please see the attachment, changes are in green color

Author Response File: Author Response.pdf