Formulation of Laurus nobilis Essential Oil Nanoemulsion System and Its Application in Fresh-Cut Muskmelons

Round 1

Reviewer 1 Report

The manuscript is representing an interesting study. The manuscript may be accepted after some points given below:

Please re-consider the title, the term used "construction" shall be replace with development or formulation.

Abstract and conclusions parts need to be rewritten.

In the abstract part, add an objective, main results, general conclusion, and more numerical data. For the first time, you cannot use uncommon abbreviations.

The stability of the emuslion has not been checked? Why?

Line 238-240 - please check: "abruptly by 89.30% in control, whereas it raised only by 15.31% " - it is correct? does not really show it in the Figure 2b.

Line 282 - was 2.07 times - higher or lower?

Author Response

1. Please re-consider the title, the term used "construction" shall be replace with development or formulation.

Thanks for suggestion. "construction" was replaced with “formulation”, so the title changed into “Formulation of Laurus Nobilis Essential Oil Nanoemulsion System and Its Application in Fresh-Cut Muskmelons”.

2. Abstract and conclusions parts need to be rewritten.

   Abstract and conclusions parts have been rewritten.

3. In the abstract part, add an objective, main results, general conclusion, and more numerical data. For the first time, you cannot use uncommon abbreviations.

Abstract has been rewritten, including an objective, main results, general conclusion, and numerical data. Uncommon abbreviations were not used.

4. The stability of the emuslion has not been checked? Why?

This formulation kept single phase after centrifuging at 4000 × g for 15 min and storage for 30 days. In addition, LNEO present in nanoemulsions was at similar concentration with freshly prepared ones after one month of storage. Furthermore, the mean particle size and PDI didn’t change during the storage. These contents have been addressed in the revised manuscript.

5. Line 238-240 - please check: "abruptly by 89.30% in control, whereas it raised only by 15.31% " - it is correct? does not really show it in the Figure 2b.

The statement is correct. After 2 days of storage period, the PPO activity had abruptly increased from 4.9777 U/g protein to 9.4230 U/g protein in control (89.30%), whereas it raised from 4.9778 U/g protein to 5.7400 U/g protein (15.31%) in coated slices. In order to be obvious, the ordinate value was reset.

6. Line 282 - was 2.07 times - higher or lower?

The correct expression is “The activity of the control sample was 2.07 times higher that of the LNEO nanoemulsion treatment at the end of storage.”

Reviewer 2 Report

Authors have elucidated the influences of Laurus nobilis essential oil (LNEO) nanoemulsion on the quality attributes of fresh-cut muskmelons (Cucumis melo L.)

English has to be improved,

The literature review is not adequate,

R&D can be improved with comparisons.

Conclusions as well

Accept the manuscript, after revision of minor mandatory changes.

Author Response

1. English has to be improved,

Thanks for suggestion. We requested English language editing, and we believe that the revised English meets the requirements.

2. The literature review is not adequate,

Thanks for suggestion. Other previous published papers regarding the effects of essential oils on quality of fresh cut melon or whole melon fruit was added in introduction or discussion section, as well as other in which essential oils from Laurus nobilis were used to preserve other fruit species.

3. R&D can be improved with comparisons.

R&D were improved by comparing with previous reports or explaining reasons.

4. Conclusions as well

Conclusions part has been rewritten.

Reviewer 3 Report

Dear Editor, in the manuscript Coatings-1480262 authors evaluated the influence of Laurus nobilis essential oil (LNEO) nanoemulsion on the quality attributes of fresh-cut muskmelons (Cucumis melo L.) during storage at 4℃ for 8 days. This is a new approach because no previous reports are available in the literature about the use of this essential oil on preserving cut-melon quality. Thus, it could be suitable for publication although the following comments should be considered:

- Line 14: Check this sentence because PAL was increased (and not inhibited) by LNEO treatments, according to Fig 2.

-Line 96: How many pieces of cut melon were packaged in each bag?

- Line 103: How many pieces were measured?

- If should be clarified if melon pieces from each bag were ground after measuring texture and colour to obtain homogeneous samples in which the remaining parameters were measured.

- Line 133: The procedure used to measure protein should be addressed.

- Line 136: Consider adding “aerobic” after total.

- Line 177: Was essential oil present in these manoemulsions after one month of storage at similar concentration than in freshly prepared ones? This is an important issue that should be addressed in the revised manuscript.

- Line 185: A decrease in firmness would be expected at least in control slices. Why it was not found?

- Line 197: Cultivars? It should be “in control and treated slices”

- Add “data are the mean ±SD (??) of n= ?? in tables and in figure legends. In addition, in tables and figures different letters or symbols should be added to show significant differences between control and treated slices.

- Line 241: It should be “two-fold” instead of “one-fold”

- Line 259: This sentence should be corrected because POX was increased by LNEO treatment.

- Line 267: Please, clarify if these changes are increases or decreases.

Other previous published papers regarding the effects of essential oils on quality of fresh cut melon or whole melon fruit could be considered in introduction r discussion section, as well as other in which essential oils from Laurus nobilis were used to preserve other fruit species:

- Scollard, J., McManamon, O., Schmalenberger, A. 2016. Inhibition of Listeria monocytogenes growth on fresh-cut produce with thyme essential oil and essential oil compound verbenone. Postharvest Biology and Technology, 120, pp. 61-68.

- Hadjilouka, A., Polychronopoulou, M., Paramithiotis, S., Tzamalis, P., Drosinos, E.H. 2015. Effect of lemongrass essential oil vapors on microbial dynamics and listeria monocytogenes survival on rocket and melon stored under different packaging conditions and temperatures. Microorganisms, 3(3), pp. 535-550.

- Moreira, S.P., de Carvalho, W.M., Alexandrino, A.C., (...), de Figueiredo, E.M.A.T., Brasil, I.M. 2014. Freshness retention of minimally processed melon using different packages and multilayered edible coating containing microencapsulated essential oil. International Journal of Food Science and Technology, 49(10), pp. 2192-2203.

- Naeem, A., Abbas, T., Ali, T.M., Hasnain, A. 2018. Effect of guar gum coatings containing essential oils on shelf life and nutritional quality of green-unripe mangoes during low temperature storage. International Journal of Biological Macromolecules, 113, pp. 403-410.

- Xu, S., Ni, Z., Ma, L., Zheng, X. 2017. Control of Alternaria Rot of Cherry Tomatoes by Food-Grade Laurus Nobilis Essential Oil Microemulsion. Journal of Food Safety, 37(1),e12286.

Author Response

1.  Line 14: Check this sentence because PAL was increased (and not inhibited) by LNEO treatments, according to Fig 2.

According to Fig 2, PAL was increased from 2.082 to 2.155 U/g protein (but not significant increase), then decreased to 1.744 U/g protein. Therefore, inhibited activities of related enzymes didn’t include PAL.

2. Line 96: How many pieces of cut melon were packaged in each bag?

One piece (about 20g) in each bag. Fifteen coated and uncoated muskmelon slices were prepared, respectively.

3. Line 103: How many pieces were measured?

Three pieces (about 60g) each treatment were measured every time.

4.  If should be clarified if melon pieces from each bag were ground after measuring texture and colour to obtain homogeneous samples in which the remaining parameters were measured.

Muskmelon pieces from each bag were ground after measuring firmness and lightness to obtain homogeneous samples in which the remaining parameters were measured.

5.  Line 133: The procedure used to measure protein should be addressed.

 The procedure used to measure protein was addressed.

6.  Line 136: Consider adding “aerobic” after total.

Thanks for suggestion. “aerobic” was added after “total”.

7.  Line 177: Was essential oil present in these manoemulsions after one month of storage at similar concentration than in freshly prepared ones? This is an important issue that should be addressed in the revised manuscript.

During the pre-experiment, we detected the concentration of essential oil in LNEO nanoemulsions stored for one month and found that it had almost no change. The content was addressed in “Physical Properties and Stability of Prepared Nanoemulsions”.

8.  Line 185: A decrease in firmness would be expected at least in control slices. Why it was not found?

It may rely on the high initial firmness values of the muskmelon pieces as well as the intrinsic varietal firmness characteristics. In fact, we observed that the firmness of muskmelons decreased gradually, but did not reach significance. We speculate that the firmness of muskmelons at least in the control group will decrease significantly after 8 days. We will confirm it in subsequent experiments.

9.  Line 197: Cultivars? It should be “in control and treated slices”

Thanks for suggestion. “in control and treated slices” replaced “cultivars”.

10.  Add “data are the mean ±SD (??) of n= ?? in tables and in figure legends. In addition, in tables and figures different letters or symbols should be added to show significant differences between control and treated slices.

“Data are the mean ± standard deviation (n = 3) and different letters in the same parameter indicate statistical significance.” was added in tables and in figure legends.

11.  Line 241: It should be “two-fold” instead of “one-fold”

“two-fold” was instead of “one-fold”.

12.  Line 259: This sentence should be corrected because POX was increased by LNEO treatment.

The correct sentence is “Therefore, our results reveal that LNEO nanoemulsion could significantly inhibit the decrease in PAL activity (p < 0.05).”

13.  Line 267: Please, clarify if these changes are increases or decreases.

“increases“ was instead of “changes”.

14. Other previous published papers regarding the effects of essential oils on quality of fresh cut melon or whole melon fruit could be considered in introduction r discussion section, as well as other in which essential oils from Laurus nobilis were used to preserve other fruit species:

- Scollard, J., McManamon, O., Schmalenberger, A. 2016. Inhibition of Listeria monocytogenes growth on fresh-cut produce with thyme essential oil and essential oil compound verbenone. Postharvest Biology and Technology, 120, pp. 61-68.

- Hadjilouka, A., Polychronopoulou, M., Paramithiotis, S., Tzamalis, P., Drosinos, E.H. 2015. Effect of lemongrass essential oil vapors on microbial dynamics and listeria monocytogenes survival on rocket and melon stored under different packaging conditions and temperatures. Microorganisms, 3(3), pp. 535-550.

- Moreira, S.P., de Carvalho, W.M., Alexandrino, A.C., (...), de Figueiredo, E.M.A.T., Brasil, I.M. 2014. Freshness retention of minimally processed melon using different packages and multilayered edible coating containing microencapsulated essential oil. International Journal of Food Science and Technology, 49(10), pp. 2192-2203.

- Naeem, A., Abbas, T., Ali, T.M., Hasnain, A. 2018. Effect of guar gum coatings containing essential oils on shelf life and nutritional quality of green-unripe mangoes during low temperature storage. International Journal of Biological Macromolecules, 113, pp. 403-410.

- Xu, S., Ni, Z., Ma, L., Zheng, X. 2017. Control of Alternaria Rot of Cherry Tomatoes by Food-Grade Laurus Nobilis Essential Oil Microemulsion. Journal of Food Safety, 37(1),e12286

Thank you very much for your comments. We have carefully studied the recommended relevant literature. The literature review was improved, and results and discussion were improved by comparing with previous reports or explaining reasons. Finally, we added 9 literatures to supplement the introduction and R&D. We have benefited a lot from them.

Round 2

Reviewer 1 Report

The authors have significantly improved the manuscript considering all reviewers' suggestions/comments. I have no more comments and I agree with its publication.