Influence of Cold Plasma Processing on the Stability of Phenolic Compounds of Araça-Boi (Eugenia stipitata) Juice

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, the influence of two cold plasma technologies, dielectric barrier discharge plasma and glow discharge plasma, on the phenolic profile of araça-boi juice was investigated and assessed by gas chromatography coupled to mass spectrum. There are good application and science value. However, there are some issues that should be carefully analysed.

(1) The abstract of the manuscript needs to add the research significance of the article.

(2) Write keywords in alphabetic order.

(3) Why is the cold plasma treatment time used for 20 minutes in Lines 123 and 125?

(4) In order to clarify the experimental method, it is suggested that the author provide a schematic diagram of the cold plasma treatment equipment in the paper.

(5) Please cite a reference for the “Chromatographic analysis” in the section 2.4.

(6) The font format of some proprietary terms should be italicized in the “References” section, such as Musa Sapientum, Goeppertia Allouia, Coffea Arabica, Garcinia Humilis, Eugenia Stipitata, etc. Suggest the author to check and make modifications.

(7) The format of magazine names is inconsistent, with some full names and some abbreviations in the “References” section. Suggest the author to check and make modifications.

Author Response

Answers to Reviewer #1 Comments:

 

1. The abstract of the manuscript needs to add the research significance of the article.

 

The abstract was revised and changed following the suggestions made by reviewers #1 and #3.

 

 

2. Write keywords in alphabetic order.

 

The keywords were ordered alphabetically.

 

 

3. Why is the cold plasma treatment time used for 20 minutes in Lines 123 and 125?

 

The processing time was fixed at 20 min because the changes observed in other araça-boi food components, such as sugars, starch, amino acids, and aroma compounds, were maximal at this processing time. This information along with references, was added to the manuscript (Page 3).

 

 

4. In order to clarify the experimental method, it is suggested that the author provide a schematic diagram of the cold plasma treatment equipment in the paper.

 

We have added a schematic diagram of both cold plasma treatment equipment, as suggested by the reviewer (Figure 2).

 

 

5. Please cite a reference for the “Chromatographic analysis” in the section 2.4.

 

A reference for the chromatographic analysis was added (Page 4).

 

 

6. The font format of some proprietary terms should be italicized in the “References” section, such as Musa Sapientum, Goeppertia Allouia, Coffea Arabica, Garcinia Humilis, Eugenia Stipitata, etc. Suggest the author to check and make modifications.

 

The reference section was revised and the font format was corrected where required.

 

 

7. The format of magazine names is inconsistent, with some full names and some abbreviations in the “References” section. Suggest the author to check and make modifications.

 

The reference section was revised and the magazine names were made consistent. The error occurred due to the use of the Mendeley software.

 

Reviewer 2 Report

Comments and Suggestions for Authors

Authors of the manuscript present the influence of cold plasma processing on the stability of phenolic compounds of araça-boi (Eugenia stipitata) juice

Lines 31-32 Please consider the sentence it is not clear for the reader.

Lines 77-78: what do the authors mean by the “other” please provide relevant literature

Lines 79-94: this paragraph should be shortened and most of the text moved to the discussion section

Lines 95-107: there is no relevant literature given

Section 2.3 Why 40^oC was chosen for the concentration?

Line 239: what other fruits are reach in cinnamic acid, literature

Could authors present the change in polyphenolic profile in graphic form? It would be easier to analyze the data

Despite the above-mentioned comments, the manuscript presents highly interesting results and may be published after minor corrections

Author Response

Answers to Reviewer #2 Comments:

 

 

1. Lines 31-32 Please consider the sentence it is not clear for the reader.

 

The text was changed to (Page 1): “Fruit juices are considered rich in vitamins, minerals, and essential nutrients, contributing to their role as functional food products. The manufacturing process of fruit juice has currently become a focal point of attention for both consumers and researchers, emerging as a prominent topic in the industry.”

 

 

2. Lines 77-78: what do the authors mean by the “other” please provide relevant literature

 

Plasma comprises dozens of reactive species. In the text, we have listed the main species that are generated in the air by the equipment we have used. Other species, such as molecular hydrogen, molecular nitrogen, ions, and nitrogen oxide, are also produced but in minor concentrations. A reference was added to the text.

 

 

4. Lines 79-94: this paragraph should be shortened and most of the text moved to the discussion section

 

This paragraph was intended to contextualize the current literature and knowledge on changes induced on phenolic compounds by plasma application. We prefer not to move to the discussion section since it consists of generic information on plasma and phenolics and does not directly correlate to the results shown in the discussion section.

 

 

5. Lines 95-107: there is no relevant literature given

 

A reference for the information was added (Page 3).

 

 

6. Section 2.3 Why 40^oC was chosen for the concentration?

 

We followed the original methodology presented by Zuo et al. The temperature for vacuum concentration was 40 ^oC because it does not degrade phenolics and is higher than the ambient temperature to increase the evaporation rate.

 

 

7. Line 239: what other fruits are reach in cinnamic acid, literature

 

Other fruits, such as Chilean strawberries (Fragaria chiloensis), physalis (Physalis peruviana), and guava (Psidium guajava), also present high concentrations of cinnamic acid in their glycosylated form. This information and references were added to the manuscript (Page 6).

 

 

8. Could authors present the change in polyphenolic profile in graphic form? It would be easier to analyze the data

 

We have tried to put the polyphenolic profile in a graphic form but there was too many information in the graph. The graph became very polluted with very narrow bar. The standard errors were difficult to see in the graph. Due to the amount of data, the table was the best option.

Reviewer 3 Report

Comments and Suggestions for Authors

I read the manuscript entitled “Influence of cold plasma processing on the stability of phenolic compounds of araça-boi (Eugenia stipitata) juice” submitted to Processes. The manuscript needs revision according to following comments:

- Abstract is very general in nature. Include important results in the abstract.

- The last part of the introduction “This study evaluate………..with a mass spectrum” should be rewritten. Have any other authors already performed such a study araça-boi (Eugenia stipitata) juice? If no, mention it is novel. If it is already been done, mention what is new in this study.

- Please provide high resolution images of araça-boi (Eugenia stipitata) plant, flower, fruit and juice. Collage these into one Fig.

- Provide the chemical structures of compound identified by GC-MS.

- How is the aromatic hydroxylation and hydrogenation possible without catalyst? Is it autocatalytic? Please go through the literature and the authors must get it checked by a chemist. Provide proper references to Figure 1.

- Everyone wants to have a good quality fresh fruit juice. Can the cold plasma processing technology be useful for small road-side vendor? What is the cost of this technology? Please discuss in the results and discussion section.

- Please include a high resolution image of complete experimental set-up in the results and discussion section.

- Are the phenolic compounds in the fruit juice stable? Have the authors measured their stability with time under storage condition? Can the juice be prepared and stored for a day or so without losing its nutritional value? This needs to be included in the form of a graph in the manuscript.

-Conclusion needs revision. Include important results and remove text.

 

- Add a few more recent references. 

 

Comments on the Quality of English Language

Minor language editing is required

Author Response

Answers to Reviewer #3 Comments:

 

1. Abstract is very general in nature. Include important results in the abstract.

 

The abstract was revised and changed following the suggestions made by reviewers #1 and #3.

 

 

2. The last part of the introduction “This study evaluate………..with a mass spectrum” should be rewritten. Have any other authors already performed such a study araça-boi (Eugenia stipitata) juice? If no, mention it is novel. If it is already been done, mention what is new in this study.

 

The last paragraph of the introduction was extended, adding the novelty of the work (Page 3): “The novelty of this work relies on further understanding the changes induced by cold plasma treatment on phenolic compounds since, up to now, only a few works on other fruits have presented this effect on the phenolic profile composition. Furthermore, the work advances in the characterization of araça-boi (Eugenia stipatata).”

 

 

3. Please provide high resolution images of araça-boi (Eugenia stipitata) plant, flower, fruit and juice. Collage these into one Fig.

 

We have a Figure with images of araça-boi (plant, flower, and fruit) (Figure 1).

 

 

4. Provide the chemical structures of compound identified by GC-MS.

 

We have a Figure with images of the chemical structures identified by GC-MS (Figure 3).

 

 

5. How is the aromatic hydroxylation and hydrogenation possible without catalyst? Is it autocatalytic? Please go through the literature and the authors must get it checked by a chemist. Provide proper references to Figure 1.

 

Plasma acts as a catalyst. These species are highly reactive due to their nature. Normally, these species are formed as intermediates by catalysts, but when plasma is applied, it generates highly reactive species that directly react with many food compounds. Figure 1 is our proposal for the reaction based on the observation made regarding the mass balance of the compounds. It does not require a reference.

 

 

6. Everyone wants to have a good quality fresh fruit juice. Can the cold plasma processing technology be useful for small road-side vendor? What is the cost of this technology? Please discuss in the results and discussion section.

 

We have extended the results and discussion section to include some insights on the technology use, cost, and availability (Page 10). In the short term, cold plasma may be applied in small to large industries because the cost would be similar to a pulsed electric field system due to the similarity between both technologies. For the street vendor, it would take longer, but on the long run we could have plasma systems at prices a little bit higher than small ozone generators since ozone is generated by plasma in this commercial equipment.

 

 

7. Please include a high resolution image of complete experimental set-up in the results and discussion section.

 

We have added a schematic diagram of both cold plasma treatment equipment, as suggested by the reviewer (Figure 2).

 

 

8. Are the phenolic compounds in the fruit juice stable? Have the authors measured their stability with time under storage condition? Can the juice be prepared and stored for a day or so without losing its nutritional value? This needs to be included in the form of a graph in the manuscript.

 

We have not performed a stability test on the juices because it was not our focus. The reason was that phenolics are known to be reasonably stable in food products, with little loss during storage. Many researches has addressed the stability of phenolic compounds, especially evaluating total phenolic compounds (TPC).

 

 

9. Conclusion needs revision. Include important results and remove text.

 

We have revised and extended the conclusion section to include the most important results (Page 8).

 

 

10. Add a few more recent references.

 

We included some new references to the text. Most of the references are from the last 5 years. Older references are important works that established the basis of plasma application in food products.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Unfortunately, I did not see the revised manuscript. I hope the author can upload the revised manuscript again.

Author Response

Answers to Reviewer #1 Comments:

 

Unfortunately, I did not see the revised manuscript. I hope the author can upload the revised manuscript again.

 

The revised version of the manuscript has been correctly uploaded to the MPDI system. We have now uploaded the third version of the manuscript to the system.

 

 

 

Answers to Reviewer #3 Comments:

 

Please include response no 5,6 and 8 in the manuscript. 

 

The response given to item 5 was added to the manuscript on Page 8. The response given to item 6 was added to the manuscript, complementing the previous discussion on Page 10 (second paragraph). The response given to item 8 was added to the manuscript on Page 10 (first paragraph).

Reviewer 3 Report

Comments and Suggestions for Authors

Please include response no 5,6 and 8 in the manuscript. 

Comments on the Quality of English Language

Minor editing is necessary. 

Author Response

Answers to Reviewer #1 Comments:

 

Unfortunately, I did not see the revised manuscript. I hope the author can upload the revised manuscript again.

 

The revised version of the manuscript has been correctly uploaded to the MPDI system. We have now uploaded the third version of the manuscript to the system.

 

 

 

Answers to Reviewer #3 Comments:

 

Please include response no 5,6 and 8 in the manuscript. 

 

The response given to item 5 was added to the manuscript on Page 8. The response given to item 6 was added to the manuscript, complementing the previous discussion on Page 10 (second paragraph). The response given to item 8 was added to the manuscript on Page 10 (first paragraph).