Aquaphotomics Monitoring of Lettuce Freshness during Cold Storage

Round 1

Reviewer 1 Report

I reviewed the manuscript entitled, Aquaphotomics Monitoring of Lettuce Freshness During Cold Storage. The manuscript is well written and contributes to the field. In my opinion, authors should consider the suggestions below.

Abstract: Please introduce the background of the study

Lines 113-116: please revise the last objective. Why is the objective in future tense? Is it the author's research or recommendation?

What is storage time (3) in line 116

Please provide the space between sold [28] and On

Provide the ref for 2.1.2. Water Activity Measurements

Please provide the ref for 2.1.3. Evaluation of Color Changes

Please provide the ref for 2.1.4. NIR spectral acquisition

Detailed methodology on PCA, LDA and PLSR should be needed with references

Section 2.3.2. Aquaphotomics multivariate data analysis is not methodology. It is background information. Please provide methodology for the statistical methods used

Lines 238-250: it's not results and just a background information

Figures 1 and 2. Why is there so much standard deviation?

Section 3.2. Water Activity Changes. Please revise it as “3.2. Water Activity”

Improve the quality of Figures 3 and 4

Line 330: Is it Figure 1 or Figure 4?

Line 384: Figure number? It seems there is a problem in Figure numbers. I suggest to revise

Line 461: Figure 7 but PCA is with Figure 4. What is correct?

Classification and validation findings are interesting and in line with literature.

Authors should revise the conclusions to reflect the conducted study and recommendations

References are not according to the journal guidelines

Author Response

Reviewer #1: General remarks

I reviewed the manuscript entitled, Aquaphotomics Monitoring of Lettuce Freshness During Cold Storage. The manuscript is well written and contributes to the field. In my opinion, authors should consider the suggestions below.

Authors’ response

We are very grateful for your endorsement of this work, and we carefully went over the Manuscript to make all the corrections you indicated.  All the revisions in the Manuscript are highlighted in yellow for easy tracking. Please find all the specific comments and our point-to-point replies below, where we describe what revision was performed and where it can be found in the revised Manuscript.

We hope that we successfully addressed all the issues and that paper can now be accepted for publication.  Thank you for investing your time and expertise to help us improve this Manuscript.

Authors

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Reviewer #1: Specific comments

Authors are very grateful for the comments of Reviewer 1.

Author Response File: Author Response.docx

Reviewer 2 Report

The experimental material comprised of ten heads of lettuce purchased in one supermarket. The material should be more diverse.

There is no detailed information on the variety, growing conditions, etc.

Considering such limited material, it is difficult to conclude the importance of the results.

Research should be carried out for a larger number of varieties with characterized growing conditions.

Author Response

Reviewer #2: General remarks

The experimental material comprised of ten heads of lettuce purchased in one supermarket. The material should be more diverse.

There is no detailed information on the variety, growing conditions, etc.

Considering such limited material, it is difficult to conclude the importance of the results.

Research should be carried out for a larger number of varieties with characterized growing conditions.

Authors’ response

Dear Reviewer,

We are very grateful for your investment of time and expertise to review our Manuscript, and we appreciate your critical opinions.

We do agree that the number of samples is small, but the manuscript we submitted and this research performed on lettuce, is just one little part of a large study we performed and which included a large variety of fruits, including different cultivars  (grapes, strawberries, avocado, banana etc.) and vegetables (lettuce, asparagus, tomato etc.), grain (rice, quinoa, wheat, etc.), as well as a variety of food products (butter, bread, coffee powder, chewing gum, crackers etc.). Our main research interest in this project was to examine the behavior of fresh food produces and food products during storage (stored at different levels of water activity ranging from 0.2 to 0.99 a_w) using aquaphotomics, understand what water activity means in the terms of water molecular structure, modeling the water activity and also exploring the effect of different storage conditions on preservation. While acquiring the spectra of all these products is rapid and easy, measuring the water activity requires much more time. Hence, to be able to test if our method is applicable for a wide variety of food products, we had to work with smaller number of samples in some cases (such as this paper).

At this point, the analysis of all the experimental data we acquired is finished and we had to think about the strategy of presenting our findings. We have chosen as a best option to present our results for each food type separately and then show the whole story with a review paper where we can summarize the findings from all these papers. The submitted lettuce manuscript is the third we submitted for publication (the first one was about the rice germ “Analysing the water spectral pattern by near-infrared spectroscopy and chemometrics as a dynamic multidimensional biomarker in preservation: rice germ storage monitoring” https://www.sciencedirect.com/science/article/pii/S1386142521009732 , and the second one is about strawberries “Aquaphotomics monitoring of strawberry fruit during cold storage – A comparison of two cooling systems” https://www.frontiersin.org/articles/10.3389/fnut.2022.1058173/full).

As we publish one by one, our findings related to different food systems, the full picture will emerge, presenting the water spectral pattern as a novel multidimensional, integrative marker that single-handedly provides information about the state of freshness, water activity, mechanical, textural and other properties of interest.    

So, based on this one paper, we very well understand that any reviewer or any reader may see our sample size as small, lacking in diversity and may question the importance of our findings. However, it is only a piece of a large body of evidence we collected, and the results we presented in the manuscript are consistent and in agreement with what we observed in our other works – that the water spectral pattern can be used to describe the state of the food system (fresh produce of product), which is something you can now also see in the papers we already published.

In the case of lettuce, we were interested in simulating the typical behavior of a consumer, who will go to the store, buy a lettuce, remove the package and store it in the fridge. We wanted to see if we can track the state of lettuce in the typical conditions after the product is bought in the supermarket and stored, so this is the reason why we did not grow the lettuce by ourselves and why the growing conditions are not supplied. We were not interested in the lettuce per se, their varieties and so on.  

We hope that this response provides better explanation about our main motivation and objective of research, and we hope that in light of this new information reviewer can better understand the importance of this work for us and why we would like it to be published as it is.  Thank you for reading and reviewing our paper, we appreciate your willingness to provide the time and expertise to the help your peers in their scientific endeavors.    

Authors

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Author Response File: Author Response.docx

Reviewer 3 Report

This MS evaluated the freshness changes during cold storage of lettuce through aquaphotomics approach. This study's results indicated that changes in cold storage lettuces are associated with alterations in water molecular structures in leaves. This MS should be proper for Foods, while the minor comments should be addressed. 1. for the '2.2 Methods' section, the 2.1.1 to 2.1.4 should be 2.2.1 to 2.2.4. 2. The figures listed in the MS are chaotic in order and are not consistent with those mentioned in the main text. 3. I would like to suggest the authors move some figures and tables that are not very important into supplemental files.

Author Response

Reviewer #3: General remarks

This MS evaluated the freshness changes during cold storage of lettuce through aquaphotomics approach. This study's results indicated that changes in cold storage lettuces are associated with alterations in water molecular structures in leaves. This MS should be proper for Foods, while the minor comments should be addressed.

Authors’ response

Dear Reviewer,

We are very grateful for your recommendation of our Manuscript for publication with only minor revisions.  All your specific comments are addressed in the point-to-point replies provided below, where we described what revision was performed and where it can be found in the revised Manuscript. All the revisions in the Manuscript are highlighted in yellow for easy tracking.

Thank you for investing your time to read and review our paper, and for the opportunity to improve its quality.

Authors

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Reviewer #3: Specific comments

Authors are very grateful for the comments of Reviewer 3.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The Authors' explanations of my comments did not bring any improvement to the manuscript.