Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion in Combination with Syzigium aromaticum and Mentha spicata Essential Oils

Round 1

Reviewer 1 Report

The authors worked on the novel strategy of protecting papaya fruits from post-harvest biodeterioration using Carnauba Wax Nanoemulsion in combination with Syzigium aromaticum and Mentha spicata Essential Oils. The study is of high interest to the scientific community and the food industry. However, the following points should be incorporated before its further processing.

Change title to “Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion in combination with Syzigium aromaticum and Mentha spicata Essential Oils”

Line 24: what is meaning of “encapsulated essential (β) oils of Syzigium aromaticum”

Line 339: replace “post-harvest disease” with “post-harvest deterioration”

What is loading capacity of both the essential oils in Carnauba Wax nanoemulsion?

Author Response

Reviewer 1

The authors worked on the novel strategy of protecting papaya fruits from post-harvest biodeterioration using Carnauba Wax Nanoemulsion in combination with Syzigium aromaticum and Mentha spicata Essential Oils. The study is of high interest to the scientific community and the food industry. However, the following points should be incorporated before its further processing.

1. Change title to “Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion in combination with Syzigium aromaticum and Mentha spicata Essential Oils”

Response: Thank you for your suggestion. We have changed the title accordingly.

2. Line 24: what is meaning of “encapsulated essential (β) oils of Syzigium aromaticum”

Response: It was modified (Line 24). “containing free or encapsulated with β-cyclodextrin (β-CD) essential oils of Syzigium aromaticum (CEO) and Mentha spicata (MEO)”

3. Line 339: replace “post-harvest disease” with “post-harvest deterioration”

Response: Thanks. We have made the changes as you suggested.

What is loading capacity of both the essential oils in Carnauba Wax nanoemulsion?

Response: The loading capacity of essential oils in carnauba wax nanoemulsion was not measured because we did not use compounds such as polysaccharides and proteins that are capable of trapping essential oils in the nanoemulsion composition. Since the oil droplets were not previously nanoemulsified, we believe that carnauba wax nanoemulsions would not be able to encapsulate them. In the beta-cyclodextrin microcapsules, the loading capacity of spearmint oil was 10.5% and clove oil was 12.4%.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript has investigated the influence of edible coatings based on carnauba wax nanoemulsion and essential oils of the post-harvest quality of papaya fruits. The manuscript is well written however the statistical analysis is not correct and the presented results are very misleading in some of the figures and tables. the authors should explain the meaning of different letters for each table or figure. In some figures/tables the treatments are compared in different days while in other figures/tables different treatments are compared in one day. 

other comments:

- Please write the magnification and ad the scale bar for SEM  imges. 

Author Response

Reviewer 2

1. The manuscript has investigated the influence of edible coatings based on carnauba wax nanoemulsion and essential oils of the post-harvest quality of papaya fruits. The manuscript is well written however the statistical analysis is not correct and the presented results are very misleading in some of the figures and tables. the authors should explain the meaning of different letters for each table or figure. In some figures/tables the treatments are compared in different days while in other figures/tables different treatments are compared in one day. 

Response: The statistical analysis was redone several times and according to the methodology described in section 2.9. The results presented in the figures and tables were obtained according to the presented methodology. In Tables 2, 3 and 4 we explain the meaning of the different letters in the footer with the sentence "Means followed by different letters on the same column indicate significant differences between treatments (p <0.05)." However, in Figures 1, 2 and 4 we do not explain the meaning of the different letters, so we add the sentence in the caption of each figure "Different letters indicate significant differences between treatments (p <0.05)".

2. Please write the magnification and ad the scale bar for SEM images. 

Response: Micrographs of the surface of the peels of papaya: magnification 50x and scale bar 500 um

Micrographs of the fractures of the peels of papaya: magnification 2000x and scale bar 10 um

We added this information in the figure 3 caption.

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript reports a study of using hydrophobic coatings infused with antimicrobial bioactive substances for improving quality stability of papaya during postharvest storage. The results show significant values and novelty. Here are some suggestions for the authors to improve the quality to be considered for acceptance.

1. Please add necessary information related to the methodology in the abstract section.

2. Please be consistent with the decimal digits.

3. Please include specific information on the equipment and software used in the study, include the model, make, city/town, country...

4. Figure 1: Were the mean comparison tests performed within each storage days or the comparison was performed for all data? For example, control group after 5 days data and 15 days data were significantly different, but were all marked the same letter. Please add necessary information as a note in the figure title. 

Please also check carefully for all the figures and tables.

Author Response

Reviewer 3

The manuscript reports a study of using hydrophobic coatings infused with antimicrobial bioactive substances for improving quality stability of papaya during postharvest storage. The results show significant values and novelty. Here are some suggestions for the authors to improve the quality to be considered for acceptance.

1. Please add necessary information related to the methodology in the abstract section.

Response: The necessary information related to the methodology in the summary section has been added on lines 24-28.

2. Please be consistent with the decimal digits.

Response: All measurements have been presented with two decimal places, except for the titratable acidity values, which have been presented with three decimal places as they need to be represented in this way for greater precision.

3. Please include specific information on the equipment and software used in the study, include the model, make, city/town, country...

Response: The information was added.

4. Figure 1: Were the mean comparison tests performed within each storage days or the comparison was performed for all data? For example, control group after 5 days data and 15 days data were significantly different, but were all marked the same letter. Please add necessary information as a note in the figure title. 

Please also check carefully for all the figures and tables.

Response: Means comparison tests were performed within each day of storage. We added the necessary information in the legend of the figures.

"Different letters indicate significant differences between treatments per day"

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript entitled “Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion and Syzigium aromaticum and Mentha spicata Essential Oils” presented the potentials of Carnauba Wax Nanoemulsion, Syzigium aromaticum and Mentha spicata Essential Oils as a coating to preserve papaya fruit. The manuscript is very well written and has scientific merit. It could be accepted after the following revisions:

Title:

-Please change the title to “Novel Approach for Improving Papaya Fruit Storage by Carnauba Wax Nanoemulsion Combined with Syzigium aromaticum and Mentha spicata Essential Oils” for better readability.  

Abstract:

-Please elaborate the term β-CD in the first appearance.

Introduction:

-Before objectives, please mention if there are relevant works available. Also, justify the novelty of your works. 

Materials and Methods:

-

-Calculating total color differences (ΔE*) would give more constructive results in color measurement.

Results and Discussion:

-Section 2.5, Line 226: “….as this avoids anaerobic conditions”. Is it anaerobic or aerobic?

Overall Comments:

 

The manuscript is vividly described, the methodology is clear and reproducible, and the discussion section is nicely explained. Some typos were observed. An improvement in the introduction would help.

Author Response

Reviewer 4

The manuscript entitled “Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion and Syzigium aromaticum and Mentha spicata Essential Oils” presented the potentials of Carnauba Wax Nanoemulsion, Syzigium aromaticum and Mentha spicata Essential Oils as a coating to preserve papaya fruit. The manuscript is very well written and has scientific merit. It could be accepted after the following revisions:

 

1. Title:

-Please change the title to “Novel Approach for Improving Papaya Fruit Storage by Carnauba Wax Nanoemulsion Combined with Syzigium aromaticum and Mentha spicata Essential Oils” for better readability.  

 

Response: Thank you for your suggestion. Another reviewer suggested this other title, very similar to this one and we thought it was more appropriate. “Novel Approach for Improving Papaya Fruit Storage with Carnauba Wax Nanoemulsion in combination with Syzigium aromaticum and Mentha spicata Essential Oils”.

 

2. Abstract:

-Please elaborate the term β-CD in the first appearance.

Response: The term β-CD was initially explained upon its first appearance in the abstract section. Additionally, it has been added to line 127.

 

3. Introduction:

-Before objectives, please mention if there are relevant works available. Also, justify the novelty of your works. 

 

Response: Thanks for the suggestion. Mention of relevant works available and the relevance of the study were added in the lines 87-93.

 

"Several studies have examined the antibacterial properties of nanoemulsions containing green mint (Zamaniahari et al., 2022), while others have investigated the antifungal potential of essential oil nanoemulsions containing thymol, which were incorporated into quinoa and chitosan films (Robledo et al., 2018). However, there is a lack of research focusing on nanoemulsions that encapsulate both clove and mint oils, despite their significant antifungal activity and potential as a safer and more natural alternative to conventional antifungal agents."

 

Added references:

 

Zamaniahari, S., Jamshidi, A., Moosavy, M. H., & Khatibi, S. A. (2022). Preparation and evaluation of Mentha spicata L. essential oil nanoemulsion: physicochemical properties, antibacterial activity against foodborne pathogens and antioxidant properties. Journal of Food Measurement and Characterization, 16(4), 3289-3300. https://doi.org/10.1007/s11694-022-01436-9

 

Robledo, N., Vera, P., López, L., Yazdani-Pedram, M., Tapia, C., & Abugoch, L. (2018). Thymol nanoemulsions incorporated in quinoa protein/chitosan edible films; antifungal effect in cherry tomatoes. Food Chemistry, 246, 211-219. https://doi.org/10.1016/j.foodchem.2017.11.032

 

4. Materials and Methods:

-Calculating total color differences (ΔE*) would give more constructive results in color measurement.

It was added to the Table 3. The discussion about ΔE has been included (Lines 285-288).

 

5. Results and Discussion:

-Section 2.5, Line 226: “….as this avoids anaerobic conditions”. Is it anaerobic or aerobic?

Response: Anaerobic conditions. The text has been modified for clarity (Lines 239-240).

6. Overall Comments:

The manuscript is vividly described, the methodology is clear and reproducible, and the discussion section is nicely explained. Some typos were observed. An improvement in the introduction would help.

Response: Thank you for your suggestions. The requested changes in the introduction have been made

Author Response File: Author Response.docx

Reviewer 5 Report

Dear authors, the article is complex and reveals that fruit quality during storage can be improved due to the wax nano-emulsions enriched with essential oils.

In abstract information from lines 24-28 should be shortened. the determination of the essential oils composition should also be mentioned in the abstract and explained better. It is related to  the fact that the composition of the EO  can affect the average droplet size of the  nano-emulsion , so CWN- CEO:β-CD may not have shown as much uniformity compared to CWN-MEO:β-CD ?

The presence or absence of mold growth in papayas during storage was evaluated  visually, and any visible spoilage was considered as decay, What do you mean by , analysis of disease incidence and severity revealed in lines 32?

 

 

I recommend the presentation of the results to be organized in chapters.

Will the eugenol from the S. aromaticum composition change the aroma of the papaya?

information in lines 248 is not clear.

Also information from line 282-283  should be integrated in lines  293.

Conclusion section should be extended since some valuable information are not highlighted, such as  That the lowest firmness values observed for CWN-MEO due to the result of the interaction of the components of this  oil with the cellular tissue of the fruit, thus is less recommended for coating. CWN-CEO coating is also less recommended  because of the determination of respiration gases, namely CO2 production rate, and O2 consumption rate . to the  Please evaluate if the microscopy analysis support this statement.

Also, the firmness changes after 10 days are strange, please provide me some information related to the the sample preparation, form and dimensions, not only the contact area.

 

Author Response

Reviewer 5

Dear authors, the article is complex and reveals that fruit quality during storage can be improved due to the wax nano-emulsions enriched with essential oils.

1. In abstract information from lines 24-28 should be shortened. the determination of the essential oils composition should also be mentioned in the abstract and explained better. It is related to the fact that the composition of the EO can affect the average droplet size of the nanoemulsion, so CWN- CEO:β-CD may not have shown as much uniformity compared to CWN-MEO:β-CD?

Response: Information from lines 24-28 should be shortened. The essential oils composition was mentioned in the abstract. In this study, the nanoemulsion formulated was based on carnauba wax. The essential oils and added microcapsules were not previously nanoemulsified. Therefore, it is believed that the composition of the oils did not affect the size of the nanoemulsions. However, the interaction between the compounds present in the essential oils with β-cyclodextrin and carnauba wax may have affected the structure of the coating. This was observed in the results of scanning electron microscopy.

2. The presence or absence of mold growth in papayas during storage was evaluated visually, and any visible spoilage was considered as decay, What do you mean by, analysis of disease incidence and severity revealed in lines 32?  

Response: The analysis of incidence and severity assesses whether there was an increase in post-harvest diseases such as anthracnose, but the term is incorrect and the sentence has been changed in the lines 34-38:

“Although the physical-chemical properties, including pH, Brix, titratable acidity, color, and texture of papayas, remained largely unchanged during storage with the coatings, analysis of incidence and severity of papaya post-harvest deterioration revealed that coatings containing essential oils effectively acted as antifungals in the fruits.”

3. I recommend the presentation of the results to be organized in chapters.

Response: Thanks for the suggestion. We separate the result and discussions into chapters.

4. Will the eugenol from the S. aromaticum composition change the aroma of the papaya?

Response: It is possible that the eugenol from could change the aroma of papaya. Eugenol is a volatile compound with a characteristic spicy aroma and is often used as a flavoring agent in food products. However, the extent of this aroma change would depend on several factors, such as the concentration of eugenol and the sensitivity of the human nose to eugenol.

5. information in lines 248 is not clear.

Response: Thanks for the suggestion. The sentence in lines 260-263 has been revised.

“Over time, the TA values of fruits tend to decrease as organic acids like citric acid are used up during respiration [62,63]. Even though there were no significant differences in the pH, TA, and TSS values, the weight loss results indicate that the coating process inhibited the fruit's respiratory system.”

6. Also information from line 282-283 should be integrated in lines 293.

Response: The information has been integrated and is on line 309-310.

“The levels of other gases, such as CO2 and O2, were also measured during storage can be seen in Figure 2.”

7. Conclusion section should be extended since some valuable information are not highlighted, such as That the lowest firmness values observed for CWN-MEO due to the result of the interaction of the components of this oil with the cellular tissue of the fruit, thus is less recommended for coating. CWN-CEO coating is also less recommended because of the determination of respiration gases, namely CO₂ production rate, and O₂ consumption rate. to the Please evaluate if the microscopy analysis support this statement.

Response: Thanks for the suggestion. The information was added (Lines 380-384).

“The coating based on CWN-MEO was less effective in reducing fruit firmness loss due to negative interactions between MEO components and fruit tissue. The CWN-CEO-based coating was also inefficient in reducing the respiration rate of the fruits. Additionally, this coating did not show good uniformity when applied to papaya fruits, as observed in SEM images. This lack of uniformity negatively impacted gas exchange reduction, resulting in low coating efficiency.”

8. Also, the firmness changes after 10 days are strange, please provide me some information related to the the sample preparation, form and dimensions, not only the contact area.

Response: The information was included. For texture evaluation of the fruits, only the removal of the fruit peel was performed according to the method described in other studies such as:

Miranda, M., Sun, X., Marín, A., Dos Santos, L. C., Plotto, A., Bai, J., ... & Baldwin, E. (2022). Nano-and micro-sized carnauba wax emulsions-based coatings incorporated with ginger essential oil and hydroxypropyl methylcellulose on papaya: Preservation of quality and delay of post-harvest fruit decay. Food Chemistry: X, 13, 100249.

dos Passos Braga, S., Magnani, M., Madruga, M. S., de Souza Galvão, M., de Medeiros, L. L., Batista, A. U. D., ... & de Souza, E. L. (2020). Characterization of edible coatings formulated with chitosan and Mentha essential oils and their use to preserve papaya (Carica papaya L.). Innovative Food Science & Emerging Technologies, 65, 102472.

Tabassum, N., & Khan, M. A. (2020). Modified atmosphere packaging of fresh-cut papaya using alginate based edible coating: Quality evaluation and shelf life study. Scientia Horticulturae, 259, 108853.

 

We are thankful to the reviewers. Their comments certainly improved the quality of our manuscript. We hope it is now suitable for publication in Coatings.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript has improved; however, the statistical analysis should be revised. In some of the Tables/figures you have used the "a" letter for the highest value while in other tables/figures, you have used "a" for the lowest value. For example, in Table 3  (the first column) the lowest value is shown as "a" while in other columns the highest value is shown as "a". Please correct all of the figures and tables.

Author Response

Reviewer 2

The manuscript has improved; however, the statistical analysis should be revised. In some of the Tables/figures you have used the "a" letter for the highest value while in other tables/figures, you have used "a" for the lowest value. For example, in Table 3 (the first column) the lowest value is shown as "a" while in other columns the highest value is shown as "a". Please correct all of the figures and tables.

Response: Thank you for your comment. We have made the necessary corrections as per your request.

Author Response File: Author Response.docx