The Development and Testing of a Temporary Small Cold Storage System: Gas-Inflated Membrane Cold Storage

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Abstract section: It is recommended that the authors spell out the full terminology before introducing abbreviations in the abstract. Moreover, abbreviations that appear only once should be omitted to maintain clarity and avoid unnecessary complexity

2.Abstract Section: The abstract lacks a clear technical context and does not adequately present the research problem. It also fails to define a specific objective—such as determining the optimal membrane configuration and gas composition—which would help clarify the study’s focus. Moreover, the experimental framework is not sufficiently outlined; readers are left uncertain about the scope of the tests conducted (e.g., mechanical, thermal, or preservation experiments) and how these were organized. The presentation of the results could be made more concise and assertive to emphasize the key outcomes rather than listing extensive numerical details.

3. Introduction Section: It is recommended that the authors strengthen the introduction by connecting their discussion of cold storage challenges in small-scale agricultural production in China to relevant international studies. While the current context is clearly described, the section lacks reference to global research on inflatable insulation, gas membrane technologies, or temporary cold storage units. Establishing these links would enhance the scientific depth of the introduction and emphasize the broader applicability of the study.

4. Introduction Section: It is recommended that the authors provide a more detailed mechanistic explanation of how the selection of gas type and multilayer membrane structure addresses the limitations of conventional cold chain systems. In addition, a brief discussion of the physical mechanisms of heat transfer—specifically the balance among conduction, convection, and radiation—should be included to clarify how these factors relate to the choice of materials and the overall thermal insulation performance.

5. Materials and Methods Section: It is not clearly stated how many replications were performed in each experiment. The authors should also clarify the control of environmental variables during the product preservation tests, such as humidity, air velocity, and defrost cycles. In addition, the statistical model (e.g., two-way ANOVA) is not explicitly described. It is recommended to include a flow chart or schematic diagram of the experimental process to better illustrate the multilayer structure and sensor placement. For the preservation test using cherry tomatoes as the model fruit, the authors should specify the sampling frequency and storage duration more clearly, rather than only referring to “20-day intervals.”

6. Discussion Section: The discussion lacks sufficient mechanistic interpretation. The authors are encouraged to elaborate on how the system reduces the heat transfer coefficient and increases the effective R-value. Furthermore, it is recommended to link the findings to potential impacts on energy savings and greenhouse gas (GHG) emission reduction to strengthen the practical significance of the study.

7. Results, Figures and Legends: It is recommended that the authors expand the figure legends to include key methodological and descriptive details currently placed beneath the figures. This adjustment would reduce redundancy in the text, improve readability, and allow each figure to be self-explanatory. For example, information about the experimental setup, measurement height, or parameter differences among sub-panels (a–f) could be integrated directly into the figure legends rather than repeated below the images.

8. Journal Suitability: Although the manuscript includes some measurements related to postharvest fruit quality—such as firmness, total soluble solids, and weight loss—the overall focus of the study remains strongly engineering-oriented. The core content emphasizes materials science, thermodynamics, and insulation design rather than food-science aspects of quality change. In its current form, the manuscript aligns more closely with engineering or applied-thermal journals than with Foods.

However, if the authors expand the study to include food-related preservation kinetics or additional quality indices—such as color, nutrient retention, or microbial load—the work could better match the aims and scope of Foods. Strengthening the food-science component would significantly improve the manuscript’s suitability for this journal.

Author Response

Thank you for your careful review. We have carried out a thorough revision as per your requirements. If you still feel unsatisfied, please let us know and we will make even greater efforts to make the necessary corrections. Thank you again!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall Manuscript Evaluation

The manuscript “The Development and Testing of a Temporary Small Cold Storage – ‘Gas-Inflated Membrane Cold Storage’” presents the design and evaluation of a temporary cold storage structure based on a gas-inflated membrane filled with cotton, compared to a conventional cold storage room of similar volume. The authors combine:

- Mechanical characterization of the membrane.

- Thermal behavior tests.

- Construction cost analysis.

- A preservation trial of cherry tomatoes stored in both chambers.

The topic is relevant to the cold chain and post-harvest preservation and fits reasonably well within the Foods field, given the focus on temperature stability and the quality of a fresh fruit and vegetable product. The concept appears innovative for the context of small-scale rural/temporary cold storage.

However, to be publishable in Foods, several aspects need significant improvement:

Clarity and robustness of the experimental design and statistical analysis, especially in the study with cherry tomatoes.

Improved connection between engineering results and real-world implications for food quality. Correction of methodological and ethical inconsistencies (e.g., the mention of informed consent). Thorough revision of the English text, as well as improvements to several figures and tables.

For all these reasons, my recommendation is a major revision.

Main Comments

Focus and Fit in the Journal of Foods

Although the work is sound from a thermal and materials engineering perspective, the current writing is heavily focused on the construction and thermal aspects, while the food quality and post-harvest physiology sections remain somewhat superficial.

I suggest expanding the Introduction to better connect the proposed system with typical post-harvest problems: weight and texture loss, color changes, rot development, potential chilling injury, etc., and with current cold chain limitations in rural contexts.

In the Discussion and Conclusions, it would be important to explain more clearly how the observed behavior (respiration, weight loss, firmness, TSS of cherry tomatoes) translates into practical advantages, equivalence, or potential limitations compared to a conventional storage chamber.

REGARDING the experimental Design and Statistical Analysis of the Cherry Tomato Trial....

The description of the cherry tomato trial is not entirely transparent; it is difficult to determine how many biological replicates there are, how sampling was conducted over time, and what the experimental unit of statistical analysis was. Please clarify:

1.- Total storage duration and specific sampling days for each parameter (respiration, weight loss, firmness, TSS). The text mentions sampling every 20 days, but then refers to a respiration peak at 3 days; this apparent contradiction needs explanation.

2.- Number of bags per treatment and time period, how many fruits per bag were analyzed, and whether the data are averaged per bag (experimental unit) or per individual fruit.

3.- Which factor(s) were included in the ANOVA (treatment, time, interaction) and whether the assumptions of normality and homogeneity of variances were verified before applying the LSD test.

4.- Please clarify whether both storage systems were loaded with the same amount of product and used a parallel and comparable trial design.

Without this precision, it is difficult to assess the robustness of the conclusions regarding preservation effectiveness.

Items as Quality Parameters, Energy Consumption, and Operational Performance

The parameters used (respiration rate, weight loss, firmness, and total soluble solids) are appropriate, but for a food journal, highly relevant information is lacking, such as:

Color (e.g., L*, a*, b*, or hue angle), which is fundamental for consumer acceptance.

Incidence of rot or at least a visual quality index (percentage of damaged fruit, presence of mold, etc.).

If this data exists, it would be highly recommended to include it (even as supplementary material).

If it was not measured, this absence should be explicitly stated as a limitation of the study, and statements about the system's "equivalence" or "suitability" for preservation should be qualified accordingly.

Energy Consumption and Operational Performance ?????

The economic analysis focuses on construction costs (insulation materials, membrane structure, etc.), showing a significant cost reduction compared to the conventional solution. However, the energy consumed by the refrigeration unit is key to the system's successful adoption.

If you have energy consumption data (kWh to maintain the same temperature setpoint and product load), you should include it or at least mention it.

If you don't have it, I suggest explicitly stating this as a limitation and discussing claims about "energy efficiency" more cautiously, focusing on improved insulation but avoiding excessive extrapolation.

Things that I Don't understand.....

The manuscript states “Institutional Review Board Statement: Not applicable,” but also claims that “Informed consent was obtained from all subjects involved in the study,” when the methodology doesn't describe any human or animal subjects.

This is inconsistent with the nature of the work, which is based on construction materials and cherry tomatoes.

I recommend removing the phrase about informed consent and leaving both sections as “Not applicable,” unless there is some part of the work involving human subjects that isn't described (in which case it should be described in detail).

Otherwise,I have more doubts about the “model layers” section and the thermal conductivity results.

In the part where the influence of the number of layers is studied, the measured thermal conductivity seems to increase with the number of membrane layers, which is counterintuitive. It mentions that the measurement methodology, designed for homogeneous materials, may not be suitable, and that convection and radiation between layers alter the apparent value, but the explanation is confusing.

It would be advisable to rewrite this section more clearly, explaining:

- the limitations of the measurement method for multilayer systems with air chambers;

- how internal convection and radiation can increase apparent conductivity;

and why, despite this, the final system with multiple layers and cotton filling offers better overall performance than conventional panels (as seen in the comparison of temperatures and overall thermal resistance).

An additional conceptual diagram (e.g., of the heat flows in the different configurations) would be helpful to Foods readers who are not heat transfer specialists.

Other issues observed in this work are related to the terminology and system names.

- Several names are used for the system throughout the manuscript (gas-inflated membrane cold storage, cotton-filled gas-inflated membrane cold storage, etc.), and in some cases, typographical errors appear (“co on”). I suggest defining a consistent, abbreviated term in the Introduction, for example:

- GIMCS = gas-inflated membrane cold storage

- CF-GIMCS = cotton-filled gas-inflated membrane cold storage

And always use these abbreviations in the text, figures, and tables.

Regarding the readability and self-sufficiency of the tables and figures in this paper, I must point out that several figures have small fonts or too much information compressed, making them difficult to read at standard journal sizes. The legends also don't always explain all the details (number of layers, experimental conditions, etc.).

- Ensure that all axes are clearly labeled with units.

- Increase the font size for axes and legends.

- Make each figure self-contained, so that the comparison is clear without constantly referring to the text.

- In the tables, define all symbols and abbreviations in footnotes and standardize the unit notation.

Another section to consider is the potential limitations and future directions of this work.

The conclusions are somewhat triumphalist, speaking of “transformative” advantages and a “strategic” technology for post-harvest handling, when several aspects have not yet been evaluated: Long-term durability of the membrane, resistance to punctures, solar radiation, etc.

Performance under heavy rain, wind, dirt, and maintenance.

Lack of energy consumption data.

The evaluation is limited to a single product (cherry tomatoes) and a specific range of conditions.

It would be advisable to add a specific paragraph on limitations in the Discussion or Conclusions section, and to formulate the conclusions in a more cautious tone, also proposing lines of future work (other plant species, multi-season trials, energy monitoring, optimization of the filling, etc.).

Other minor, but also important, comments that the authors should modify in the paper are the following:

- The manuscript requires a thorough review of the English: there are grammatical errors, unnatural constructions, and quite a few typos (for example, “co on” instead of “cotton,” words broken by line breaks, etc.).

I strongly recommend professional proofreading or review by a native speaker.

- Please particularly review the Abstract, Introduction, and Conclusions, shortening overly long and redundant sentences.

- The abstract is informative but somewhat long and dense.

Check if Foods currently requires a structured abstract (Background, Methods, Results, Conclusions).

In any case, it would be desirable to simplify it, highlighting:

- The problem (need for temporary and low-cost cold storage chambers).

- The proposed solution (gas-inflated membrane and cotton filling).

- The main quantitative results compared to the conventional chamber. Key findings and, if possible, a brief comment on limitations.

Standardize the use of units:

- W/(m·K) for thermal conductivity.

- mg CO₂/(h·kg) for respiration rate.

- Always use °C for temperature.

- Verify that all units in tables and figures are consistent and correct.

Verify that the reference format conforms to Foods standards (journal name, volume, pages, DOI, etc.).

Check that all cited references appear in the reference list and that no references in the list are not cited in the text.

The author contribution statement is acceptable, but it could be aligned with the MDPI CRediT taxonomy if the system requests it (Conceptualization, Methodology, Investigation, Writing—Original Draft, etc.). Regarding data availability, it would be helpful to indicate whether raw data (e.g., individual temperature, respiration, etc. readings) can be provided upon reasonable request.

Typographical details: Correct all hyphenated words at the end of a line (e.g., “membrane,” “environment”). Review figure titles and captions to eliminate spelling errors or minor inconsistencies.

 

Comments on the Quality of English Language

The manuscript requires a thorough review of the English: there are grammatical errors, unnatural constructions, and quite a few typos (for example, “co on” instead of “cotton,” words broken by line breaks, etc.).

I strongly recommend professional proofreading or review by a native speaker.

 

Author Response

Thank you for your careful review. We have carried out a thorough revision as per your requirements. If you still feel unsatisfied, please let us know and we will make even greater efforts to make the necessary corrections. Thank you again!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This research is about The Development and Testing of a Temporary Small Cold Storage - "Gas-Inflated Membrane Cold Storage". It is interesting and useful for readers to use. If there are some corrections to make it more complete.

1. Abstract: The abstract should be clear, concise, and complete, covering all key points in a structured manner. Key findings from the present study should be included.
2. Introduction: The introduction should be improved by including relevant research. What gaps have these studies not addressed or require further research?
3. Introduction: What is the main question of this research? Detail the problem and its origins.
4. Introduction: How does this research address these issues and what are its strengths?
5. Experimental Treatments: It is recommended to add step-by-step illustrations to explain the research procedure in detail.
6. Materials and Methods: The current writing style is similar to a thesis or research report. The writing style should be concise and references should be added where necessary.
7. Fig. 4, 7, 8,10, 11, and 14: The image size should be adjusted to be clearly visible.
8. 3.1.1. Selection of Materials for Gas-Inflated Membrane Structures: “Specifically, higher PA content improves tensile strength, stiffness, and heat resistance, albeit at the expense of reduced flexibility and elongation at break. In contrast, increased PE content enhances ductility and elongation capacity but leads to diminished structural integrity and lower thermal stability,” references and related research should be added.
9. 3.1.1. Selection of Materials for Gas-Inflated Membrane Structures: Consideration should be given to adjusting the presentation format to be concise. Sections that can be combined with both figures and tables should be presented together. The format for writing the description of the experimental results should be adjusted to be concise, emphasizing the important content. Discussion of the results should be added in an academic manner and references should be added.
10. Table 4. Gas performance and price reference table: Safe concentration has other symbols inserted. Should be checked.
11. 3.2.1. Determination and optimization of number of model gas-inflated membrane layers: Discussion of the results should be added in an academic manner and references should be added.
12. Conclusion: The summary should be rewritten. The summary should be rewritten to reflect the main question. Suggestions and guidelines for further research or applications should be included.
13. Should add an abbreviation section
14. Check the reference format to ensure it complies with the Foods journal's guidelines.

Author Response

Thank you for your careful review. We have carried out a thorough revision as per your requirements. If you still feel unsatisfied, please let us know and we will make even greater efforts to make the necessary corrections. Thank you again!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has made adjustments based on the feedback.

Author Response

Here is my revised manuscript once again – I’m truly grateful for all your hard work and support! Wishing you the very best of luck!

Reviewer 2 Report

Comments and Suggestions for Authors The authors have addressed most of the modifications proposed in the previous review, resulting in a substantial improvement to the manuscript, particularly regarding the clarity of the experimental design, the description of the cherry tomato preservation trial, the definition of replicates and statistical analysis, and the expansion of the quality parameters analyzed, incorporating physiological and biochemical indicators that strengthen the article's suitability for the journal Foods. Overall, the article now presents a more solid experimental basis and greater scientific depth. However, some minor aspects remain that should be corrected before final acceptance, mainly of a formal and editorial nature. Specifically, it would be advisable to: improve the coherence and fluency of the English language through a more careful linguistic review; eliminate repetitions and redundancies detected in some sections of Materials and Methods; unify and clarify the statistical analysis section, avoiding the simultaneous mention of different tests without clear justification; correct minor typographical and formatting errors, section numbering, duplicate titles. These issues do not substantially affect the scientific validity of the study, but correcting them would contribute to improving the clarity and overall presentation of the manuscript. Comments on the Quality of English Language

It would be advisable to: improve the coherence and fluency of the English language through a more careful linguistic review

 

Author Response

We have revised the manuscript based on your feedback—we truly appreciate your efforts! If there are any areas that still need improvement, please do let us know, and we will continue working diligently to make it better. Once again, thank you for all your dedication！

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article has been revised and improved according to the suggestions.
This article is now suitable for publication in the journal Foods.

Author Response

Here is my revised manuscript once again – I’m truly grateful for all your hard work and support! Wishing you the very best of luck!