Investigation into Solar Drying of Moroccan Strawberry Tree (Arbutus unedo L.) Fruit: Effects on Drying Kinetics and Phenolic Composition

Round 1

Reviewer 1 Report

The manuscript investigated the potential use of a solar dryer under Moroccan 400

environmental conditions, to dry Arbutus unedo L. The study fully described the drying kinetics of the indirect forced convection solar dryer (effective diffusivity, activation energy, total energy usage). The manuscript was written in good English and clarity. I missed error bars in all the Column charts shown in this study. Another question is that the difference between the solar dryer and the common Oven-drying method on the polyphenols.

Author Response

Dear reviewer,

 

Thank you very much for your precisous comments on our manuscript.

Please find below the answers to these commnets.

Best regards,

On behalf authors,

Othmane Merah

Reviewer # 1

 

The manuscript investigated the potential use of a solar dryer under Moroccan environmental conditions, to dry Arbutus unedo L. The study fully described the drying kinetics of the indirect forced convection solar dryer (effective diffusivity, activation energy, total energy usage). The manuscript was written in good English and clarity.

. Another question is that the difference between the solar dryer and the common Oven-drying method on the polyphenols.

The effects on drying methods on phenolic compounds was reported, compared in the body text to enrich the discussion

 

Reviewer 2 Report

The presented work is in general interesting and presents thoroughly the drying process of the examined fruit. However, the manuscript have some points than need to be significantly improved in order to highlight the research work in a more appropriate way.

1. The introduction is very poor- there is no reference in similar works, methods used or findings of other research papers. The only thing that is highlighted is the situation in Morocco concerning the examined fruit. The problem is well described but the reason for using this system is not referred. Advantages, weaknesses of other methods etc.

2. In the material and methods section, sub paragraph 2.3.4 (lines 144-154). You are referred to microwaves. If I understood well your system doesn't include a microwave heater in any part ( I have read your previous work). Please rewrite this part because it is confusing. In line 153 you are calculating the density not the specific air capacity of the air inlet as referred in lines 151-152. This whole part needs to be corrected

2. In lines 272- 274 rephrase- it is not well explained why the Deff is increased. Describe the phenomena more clearly (interaction between moisture at the surface of the sample and the environment)

3. Figure 9 should be reformed. The difference  in the contribution of solar energy to the process is not visible. Maybe change the scale of y axis. It is one of the main findings of your work 

4. According to the phenolic compound analysis, check if there are more parameters affecting the phenolic compounds beyond the temperature. There are research works that highlight differences between thermal methods and their impact on the composition of dried fruits. I. e solar radiation doesn't affect it? 

5. The conclusions part should be expanded

6. Also language should be improved. There are many parts that the text doesn't make sense or the words used are not right. For example

Line 24:  Solar drying is affordable, requiring low energy and an eco-friendly method. Maybe "solar drying is an affordable, low energy and eco-friendly method."

Line 59-62: Also, its efficiency in converting these highly perishable fruits into more stabilized dried fruits while maintaining their quality and extending their shelf life by storing them under a minimal controlled environment.  Maybe add something like "is evaluated" or "is examined" at the end of the phrase

Line 179:  to assess the goodness of fit. Rephrase

And many other typos (chain instead of chaine) etc

Please check the whole manuscript for language issues

Author Response

Dear reviewer,

 

Thank you very much for your precisous comments on our manuscript.

Please find below the answers to these commnets.

Best regards,

On behalf authors,

Othmane Merah

 

Reviewer # 2

The presented work is in general interesting and presents thoroughly the drying process of the examined fruit. However, the manuscript has some points than need to be significantly improved in order to highlight the research work in a more appropriate way.

1. The introduction is very poor- there is no reference in similar works, methods used or findings of other research papers. The only thing that is highlighted is the situation in Morocco concerning the examined fruit. The problem is well described but the reason for using this system is not referred. Advantages, weaknesses of other methods etc.

Similar works and research on strawberry fruits were reported. Drying methods and their findings specifically on strawberry tree fruits are reported as well in both the introduction and discussion part. Also justification of selecting the dryer as well its advantages are being reported in the introduction session as per the reviewer request

In the material and methods section, sub paragraph 2.3.4 (lines 144-154). You are referred to microwaves. If I understood well your system doesn't include a microwave heater in any part ( I have read your previous work). Please rewrite this part because it is confusing. In line 153 you are calculating the density not the specific air capacity of the air inlet as referred in lines 151-152. This whole part needs to be corrected

We thank the reviewer for his comment. It was a mistyping and we corrected it in the revised version.

2. In lines 272- 274 rephrase- it is not well explained why the Deff is increased. Describe the phenomena more clearly (interaction between moisture at the surface of the sample and the environment).

The sentences were rephrased and the Deff phenomena was more described in details

3. Figure 9 should be reformed. The difference  in the contribution of solar energy to the process is not visible. Maybe change the scale of y axis. It is one of the main findings of your work 

The figure 9 was modified.

4. According to the phenolic compound analysis, check if there are more parameters affecting the phenolic compounds beyond the temperature. There are research works that highlight differences between thermal methods and their impact on the composition of dried fruits. I. e solar radiation doesn't affect it? Screening of the literature regarding the effect of thermal methods on the phenolic compounds was done, and related findings were incorporated when appropriate.
5. The conclusions part should be expanded: The conclusion was detailed further as per the reviewer request
6. Also language should be improved. There are many parts that the text doesn't make sense or the words used are not right. For example

Line 24:  Solar drying is affordable, requiring low energy and an eco-friendly method. Maybe "solar drying is an affordable, low energy and eco-friendly method."

The sentence was rephrased

Line 59-62: Also, its efficiency in converting these highly perishable fruits into more stabilized dried fruits while maintaining their quality and extending their shelf life by storing them under a minimal controlled environment.  Maybe add something like "is evaluated" or "is examined" at the end of the phrase

Line 179:  to assess the goodness of fit. Rephrase/ done

And many other typos (chain instead of chaine) etc done

Please check the whole manuscript for language issues:

The whole manuscript was checked and edited by a near-native English speaker to spot any possible language errors

Reviewer 3 Report

The article illustrates the solar drying of Moroccan strawberry tree. There are several communication problems: from English at times difficult to understand, to the confusion about the terms and concepts used. To improve the quality of the article, the following are suggested:

In the first paragraph of the introduction, the reference should be mentioned at the end of this paragraph.

Author should add the novelty of this work in the first paragraph of the introduction section and add a clear hyphothesis in the last paragraph.

This paper does not explain the contribution and motivation of this study. Why is this case critical? What's the new contribution?

Why three drying temperatures were chosen? Why temperatures of 40 and 50 were not used?

In line 98, the equilibrium humidity value of the environment should be mentioned

Equations should be written according to the journal format

Figure 2 is ambiguous! First, the horizontal graph should show the hours of the day, not the drying time, secondly, I did not see the relative humidity graph to know how much it is during different hours. Thirdly, for the temperature axis, like the two horizontal and vertical axes, the word temperature and its unit should be written.

In figure 3b, the related points should be connected with a line to make it easier for the reader to understand.

The results related to mathematical modeling should be moved to the beginning of the results section in section 3-2.

The results of Table 5 should be checked by statistical analysis for their significance or non-significance.

It is better to write the discussion section separately from the conclusion and expand it with previous research. The following articles are suggested to compare the results.  Foods 2022, 11, 784, Sustainable Energy Technologies and Assessments 2022, 49, 101763, Energies 2021, 14, 5835, Energy 2021, 220, Renewable Energy 2021, 163, 495-503, Journal of Food Process Engineering 2021, 44, e13588, Journal of Cleaner Production 2021, 282, 124421

 

Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.

 

Author Response

Dear Reviewer,

 

Thank you so much for your precious comments which helped us in imprving the manuscript.

Please find below the answers to these comments.

 

Best regards,

On behalf authors,

othmane merah

 

The article illustrates the solar drying of Moroccan strawberry tree. There are several communication problems: from English at times difficult to understand, to the confusion about the terms and concepts used. To improve the quality of the article, the following are suggested:

In the first paragraph of the introduction, the reference should be mentioned at the end of this paragraph.

The introduction was fully developed to take in considerations all reviewers comments and propositions.

Author should add the novelty of this work in the first paragraph of the introduction section and add a clear hypothesis in the last paragraph.

Both the novelty and hypothesis were added to the introduction

This paper does not explain the contribution and motivation of this study. Why is this case critical? What's the new contribution?

Why three drying temperatures were chosen? Why temperatures of 40 and 50 were not used?

The studied drying temperatures are chosen based on a thermodynamic study (work not yet published).

In line 98, the equilibrium humidity value of the environment should be mentioned:

Corrected

Equations should be written according to the journal format

Figure 2 is ambiguous! First, the horizontal graph should show the hours of the day, not the drying time, secondly, I did not see the relative humidity graph to know how much it is during different hours. Thirdly, for the temperature axis, like the two horizontal and vertical axes, the word temperature and its unit should be written.

The title of the horizontal graph was modified.

The temperature axis presented both the ambient air temperature (°C) and the ambient air

relative humidity (%).

In figure 3b, the related points should be connected with a line to make it easier for the reader to understand.

The points are scattered; we cannot relate points with a line.

The results related to mathematical modeling should be moved to the beginning of the results section in section 3-2.

The section was moved as per the reviewer comment to cement the body text well.

The results of Table  should be checked by statistical analysis for their significance or non-significance. Significance letters were added to the table as per the reviewer comment

It is better to write the discussion section separately from the conclusion and expand it with previous research. The following articles are suggested to compare the results.  Foods 2022, 11, 784, Sustainable Energy Technologies and Assessments 2022, 49, 101763, Energies 2021, 14, 5835, Energy 2021, 220, Renewable Energy 2021, 163, 495-503, Journal of Food Process Engineering 2021, 44, e13588, Journal of Cleaner Production 2021, 282, 124421

 Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.

The authors totally agree with the reviewer comment. The results and discussion were improved by reporting simar works to enrich the discussion, the suggested works were checked and incorporated in the text where appropriate, also other works were added to enhance the clarity of the results and compared with the previous research works being done up to now.

Round 2

Reviewer 2 Report

Dear authors

The manuscript has been improved according to the comments. However, You are still mentioning microwave in lines 192-203. Also in lines 200-203 you are calculating density and you are mentioning that you are calculating specific heat. Please rephrase to make it clearer if you calculate both

Reviewer 3 Report

Thanks for addressing my comments and improving the manuscript. The improvements were satisfactory and I am recommending the manuscript to be published in applsci journal.