Resource Utilization Enhancement and Life Cycle Assessment of Mangosteen Peel Powder Production

Round 1

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

1-           In the abstract, the authors did not address the primary contributions of this study and its advantages compared to other research works.

2-           The introduction section needs to be drastically improved since all the sources cited in this section all outdated. We encourage the authors to consider the recently published papers in this field in order to find out the contributions of their study.

3-           The necessity and practical justification for conducting this research should be better explained in the introduction.

4-           The research goals  and objectives should be provided in a separate paragraph in the introduction section.

5-           The research questions should be given in the introduction section.

6-           The novelties of this study should be explained in the introduction section based on the recently published studies.

7-           The English language used is appropriate and clear, but needs minor revisions.

8-           The literature review is missing. The authors must bring the recently published papers (2023, 2024, and 2025) to this section. 

9-           The literature review should be organized in a manner so that similar studies and their cons and pros are analyzed and discussed. In addition, the literature review section should be categorized into different sub-sections. 

10-         A literature review table should be provided in the literature review section to clearly demonstrate the research gaps and the novelties of this study.

11-         The sampling data have not been thoroughly provided.

12-         Enough justifications for using the proposed methods should be provided.

13-         A flowchart of research methodology should be added.

14-         There is not enough discussion about the results.

15-         The outcomes should be compared with the similar studies.  The theoretical implications should be provided before conclusion.

16-         The practical implications and managerial discussions should be provided before conclusion.

17- Research limitations should be clearly provided in the conclusion.

18-         Suggestions for future research should be modified and provided in a better manner.

19- How come the authors have not used the AI in their research methodology?

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in blue font.

Sincerely,

Alisa Soontornwat et al.

For easy visualization, the responses to the reviewer’s comments are provided below in blue font.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

This study presents a life cycle assessment (LCA) applied to the environmental evaluation of a specific process, aiming to determine its sustainability performance. The LCA methodology follows the ISO 14040 and 14044 standards, considering multiple impact categories such as global warming potential (GWP), fossil resource depletion, and ecotoxicity. The analysis compares alternative process configurations, identifying the most environmentally favorable scenario based on a cradle-to-grave or gate-to-gate system boundary.

 

Strenghts of this manuscript:

• Robust methodological framework: The study adheres to established LCA standards, ensuring transparency and comparability.
• Detailed scenario analysis: Different process configurations are compared, allowing for a nuanced understanding of environmental trade-offs.
• Holistic impact assessment: A wide range of environmental categories are analyzed, providing a comprehensive picture of sustainability performance.

 

Recommendations for improvement:

• Provide clearer interpretation of trade-offs: Highlighting specific impact categories where trade-offs exist (e.g., low GWP but high water consumption) would enhance the applicability of findings.
• Briefly discuss the expectations of different energy sources and energy mixes: A short discussion on how different energy sources might influence the results would be beneficial. You could take this work as a reference (10.1016/j.jclepro.2024.144174), they extensively analyzed these aspects through a sensitivity analysis.

Author Response

Comment 1: Recommendations for improvement:

Provide clearer interpretation of trade-offs: Highlighting specific impact categories where trade-offs exist (e.g., low GWP but high water consumption) would enhance the applicability of findings.

Briefly discuss the expectations of different energy sources and energy mixes: A short discussion on how different energy sources might influence the results would be beneficial. You could take this work as a reference (10.1016/j.jclepro.2024.144174), they extensively analyzed these aspects through a sensitivity analysis.

Response 1: As per your suggestion, the Discussion of Research Findings section has been enhanced with more detailed discussions and additional references (as appeared below). Additionally, the suggested reference (10.1016/j.jclepro.2024.144174) has been incorporated into the Discussion section of the revised manuscript.

Table 5 tabulates the total GWP of MPP production scheme 1 – 6 and scenarios A and B. As seen in the table, the total GWP of schemes 1, 2, and 3 are 6.73760 kgCO₂eq, 17.62724 kgCO₂eq, and 20.89217 kgCO₂eq, respectively. Scheme 4 (frozen storage and freeze drying) has the highest GWP of 1,091.8969 kgCO₂eq. The very high GWP is due to high energy consumption of freeze drying process. On the other hand, scheme 5 (frozen storage and sun drying) has the lowest GWP of 0.03072 kgCO₂eq The very low GWP is attributable to sun drying, which requires no electricity. However, the end product (i.e., MPP) has a high microbial count. The total GWP of scheme 6 is 11.23585 kgCO₂eq. Scheme 6 is adopted as the optimal processing scheme due to the high quality MPP and its low GWP.

By comparison, hot air drying (i.e., schemes 1, 2, 3, 6) has a lower GWP compared to freeze drying (scheme 4) due to lower electricity consumption. Since hot air drying process relies primarily on heat energy, the heat can be sourced from liquified petroleum gas [55] or an energy mix [56], resulting in a lower GWP. Meanwhile, the total GWP of scenarios A and B are 11.83423 kgCO₂eq and 11.24116 kgCO₂eq, respectively. The higher total GWP of scenario A could be attributed to the need for refrigerated trucks to transport frozen mangosteen peels from Chumphon province to Bangkok; and for frozen storage to store the frozen mangosteen peels upon arrival in Bangkok.

Essentially, the conversion of mangosteen peels (i.e., agricultural waste) into value-added MPP enhances resource use and improves the sustainability of mangosteen farming, aligning with SDG 12: Ensure sustainable consumption and production patterns, which is key to sustaining the livelihoods of current and future generations. Additionally, converting mangosteen peels into MPP decreases the amount of agricultural waste disposed of in landfills, thereby reducing GHG emissions which are the primary driver of climate change, aligning with SDG 13: Take urgent action to combat climate change and its impacts.

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

As I mentioned the problems in the first submission, there was a lack of additional information and revised content regarding them.

At first, The research's boundaries and targets are unclear, and there is no concrete evidence or proper background to support the hypothesis.

The second point is that there is no relevant previous research survey. As a result, this paper could not show the research story and there is a lack of data collection.

The figures 1 and 2 that you explained 6 schemes showed the emission to water and soil. That is, every process has an environmental impact on the air and river. However, you are only evaluating carbon dioxide in this research. It's challenging to find originality and academic value in the LCA results.

Author Response

Comment 1: At first, The research's boundaries and targets are unclear, and there is no concrete evidence or proper background to support the hypothesis.

Response 1: As per your comments, revisions have been made to the system boundary of the LCA to enhance the clarity and accurately represent the scope of the assessment (as seen below in the Goal and scope definition subsection). 

Additionally, we have made significant improvements to the Introduction section to identify the research gap, describe the research objectives, and highlight the research originality (as seen below in the Introduction section). Moreover, the Discussion of Research Findings section has been enhanced with more detailed discussions and additional references (as seen below).

2.2.1 Goal and scope definition

In this study, the goal of LCA is to assess the GWP associated with the conversion of mangosteen peels (i.e., agricultural waste) to dried mangosteen peel powder (i.e., value-added product). The scope of LCA is of gate-to-gate system boundary, starting from the point where raw materials (i.e., mangosteen peels) enter the conversion process and ending when the finished product (i.e., MPP) leaves the processing facility, excluding any impacts from raw material extraction, product use and disposal.

The aim is to identify the MPP production scheme that produces high-quality MPP with low GWP. There are six MPP production schemes being studied: schemes 1 – 6, as shown in Figure 1. The functional unit is 1 kg of MPP. A defined functional unit enables the meaningful comparison and analysis [34].

 

1. Introduction

Mangosteen (Garcinia mangostana L.) is renowned for its unique flavor and health benefits, including anti-inflammatory, antioxidant, and antimicrobial properties [1-5]. The global mangosteen production in 2023 stood at approximately 700,000 metric tons, with more than one third (240,000 metric tons) originating from Thailand's southern province of Chumphon [6]. The perishability of mangosteen presents post-harvest challenges for mangosteen growers, thereby necessitating efficient post-harvest management to reduce waste and enhance resource use.

Mangosteen pericarp accounts for 70% of the fruit's total weight and is normally discarded as agricultural waste in landfills [7]. The practice is harmful to the environment as improperly treated agricultural waste emits greenhouse gases (GHG) into the atmosphere. Research has shown that landfill treatment of solid waste is the largest contributor of GHG emissions [8]. The environmental impacts of GHG emissions have sparked interests in environmentally-friendly solutions to valorizing agricultural waste [9]. Fruit waste, which is a type of agricultural waste, can be converted into high-value bioproducts such as bioactive compounds, organic acids, and biofertilizers [10-11].

Mangosteen peels are rich in bioactive compounds, including α-mangostin, catechins, polyphenols, and xanthones [12-15]. These bioactive compounds are active ingredients in cosmetic and pharmaceutical products [16,17]. Unlike fresh mangosteen pericarp which has a low economic value (0.2 USD per 1 kg), the market price of pure xanthones extracted from mangosteen pericarp is significantly higher (0.55 USD per 1 kg), and 1 kg of fresh mangosteen pericarp contains 2 g of pure xanthones [18,19]. However, fresh mangosteen peels have a high moisture content (65 – 70%), making it susceptible to spoilage [20]. As a result, drying mangosteen peels before processing reduces the moisture content and extend the shelf life while preserving the essential bioactive compounds.

Life Cycle Assessment (LCA) is a process of compiling and evaluating inputs, outputs, and potential environmental impacts of a product system throughout its life cycle (ISO 14040, 2006a). LCA has been applied to analyze the environmental impacts of food production and consumption, including GHG emissions [21].

Existing LCA research focused on the environmental impacts of valorizing fruit waste using different processing processes, such as hydrolysis, extraction, extrusion, distillation, digestion, and drying [22-29]. In [22], the environmental impacts of hydrolysis, distillation, and anaerobic digestion processes from citrus peels were assessed using LCA. In [23], LCA was employed to evaluate the environmental impacts of hydrolysis and extraction processes from orange peels. In [24], the environmental impacts of extrusion process of orange peels for soluble dietary fiber were assessed using LCA. The environmental impacts of orange peels thermally treated with autoclave machine were evaluated using LCA, and the physicochemical properties of the processed product (i.e., soluble dietary fiber) were determined [25].

In [26], LCA was utilized to assess the environmental impacts of distillation and extraction processes from orange peels. In [27], the environmental impacts of different extraction methods from orange peels were investigated, and the results were compared. The LCA environmental impacts of dried pomegranate peels treated with digestion, hydrolysis, and extraction processes were evaluated, and the bioactive compounds of the processed products were analyzed [28]. In [29], LCA was applied to assess the environmental impacts of extraction processes from mango kernel. Table 1 summarizes research studies on valorization of food waste or agricultural waste.

In Thailand, LCA has been employed to evaluate the environmental impacts (from cultivation to retailers) of mango and mangosteen [30]. The GHG emissions of one kilogram of mangosteen are reported to be 1.71 kgCO₂eq [31]. In contrast, the Thailand Greenhouse Gas Management Organization reported that the GHG emissions of mangosteen are 0.89 kgCO2eq [32]. The large discrepancy (1.71 vs 0.89 kgCO2eq) could be attributed to electricity demanded to pump water to irrigate mangosteen trees. As a result, converting mangosteen peels into mangosteen peel powder can reduce agricultural waste and GHG emissions.

There are currently no research studies dedicated to on the Global Warming Potential (GWP) of the production of dried mangosteen peel powder (MPP) from fresh mangosteen peels. Existing research on MPP production focuses primarily on the product quality, including the physical, chemical, and biological properties.

As a result, the aim of this research is to investigate GWP of six MPP production schemes from fresh mangosteen peels. LCA is employed to assess GWP associated with each processing step of different MPP production schemes, such as coarse grinding, quick freezing, frozen storage. Besides, the physical, chemical, and biological properties of MPP from different schemes are compared. The optimal MPP production scheme in terms of GWP and product quality is subsequently identified.

However, due to the lack of an onsite hot-air drying facility, two transportation strategies are incorporated into the optimal MPP production scheme (i.e., frozen storage without coarse grinding and hot air drying scheme; scheme 6). The two transportation strategies are: (i) transporting frozen mangosteen peels by refrigerated trucks from Chumphon province to a hot-air drying facility in Bangkok (scenario A); and (ii) hauling a mobile hot-air drying unit using a semi-trailer truck to Chumphon province (scenario B).

Specifically, this study aims to answer the following questions: (i) Which MPP production scheme has the lowest GWP, and which has the highest GWP?; (ii) Which MPP production scheme achieves both acceptable product quality and low GWP (i.e., the optimal scheme)?; and (iii) Which transportation strategy (i.e., scenario A or B) is more environmentally-friendly in terms of GWP?

This research is the first to comparatively investigate the GWP of different MPP production schemes using LCA. This research also aligns with the growing trend in international trade which attaches greater importance to environmentally-friendly products and production processes. Furthermore, the findings of this study are expected to contribute toward achieving the United Nations’ Sustainable Development Goals 12 (Responsible consumption and production) and 13 (Climate action).

 

 

4. Discussion of Research Findings

The research findings indicate that the drying process (i.e., hot air drying and freeze drying) has the most significant environmental impact, primarily due to high electricity consumption. In hot air drying, the low enthalpy takes a long time to dehydrate mangosteen peels, resulting in a loss of energy through the dryer walls and outlet [45]. Insulating the dryer can improve the drying rate and reduce the drying time and energy consumption [46,47].

By comparison, freeze drying takes considerably longer time, resulting in higher electricity consumption and higher GHG emissions. Cooling and freezing vegetables and fruits is energy-intensive and is a major contributor of GHG emissions [48]. The energy consumption in freeze drying is substantially higher than in hot air drying due to differences in drying durations and system complexity [49]. Specifically, freeze drying involves two stages including freezing and drying, while hot air drying involves only one stage, i.e., hot air drying to dehydrate the product. In addition to the long drying duration (24 h minimum) and high energy consumption, freeze drying systems require large financial investments, thereby limiting its application. For example, freeze drying 1000 kg of green onions requires 1080 kWh of electricity [50], significantly impacting the environment by contributing to greater GHG emissions.

Despite the lowest GWP, sun drying (scheme 5) suffers from the product quality issues as the microbial counts in MPP exceed the safety limits for dried herbal products [36]. Sun-dried foods are prone to contamination as the sun drying process exposes the food products to the elements (i.e., atmospheric conditions) [51,52]. Nevertheless, sun drying is commonly practiced in many tropical countries to preserve food products. For example, in Thailand, sun drying results in low-quality dried banana products as the bananas are directly exposed to the elements [53].

In addition, the study reveals that scheme 1 (coarse grinding without frozen storage and hot air drying) is not practical because fresh mangosteen peels have a short shelf life and are highly perishable. As a result, effective management of fresh mangosteen peels (i.e., frozen storage) is essential to maintain their freshness.

The results also indicate that transportation choice (between scenarios A and B) plays a role in lowering the overall environmental impact. This is consistent with Zdravkovic, Snoeck [54] , who reported that a mobile processing unit is more environmentally-friendly than transporting apples to a distant location for processing.

Table 5 tabulates the total GWP of MPP production scheme 1 – 6 and scenarios A and B. As seen in the table, the total GWP of schemes 1, 2, and 3 are 6.73760 kgCO₂eq, 17.62724 kgCO₂eq, and 20.89217 kgCO₂eq, respectively. Scheme 4 (frozen storage and freeze drying) has the highest GWP of 1,091.8969 kgCO₂eq. The very high GWP is due to high energy consumption of freeze drying process. On the other hand, scheme 5 (frozen storage and sun drying) has the lowest GWP of 0.03072 kgCO₂eq The very low GWP is attributable to sun drying, which requires no electricity. However, the end product (i.e., MPP) has a high microbial count. The total GWP of scheme 6 is 11.23585 kgCO₂eq. Scheme 6 is adopted as the optimal processing scheme due to the high quality MPP and its low GWP.

By comparison, hot air drying (i.e., schemes 1, 2, 3, 6) has a lower GWP compared to freeze drying (scheme 4) due to lower electricity consumption. Since hot air drying process relies primarily on heat energy, the heat can be sourced from liquified petroleum gas [55] or an energy mix [56], resulting in a lower GWP. Meanwhile, the total GWP of scenarios A and B are 11.83423 kgCO₂eq and 11.24116 kgCO₂eq, respectively. The higher total GWP of scenario A could be attributed to the need for refrigerated trucks to transport frozen mangosteen peels from Chumphon province to Bangkok; and for frozen storage to store the frozen mangosteen peels upon arrival in Bangkok.

Essentially, the conversion of mangosteen peels (i.e., agricultural waste) into value-added MPP enhances resource use and improves the sustainability of mangosteen farming, aligning with SDG 12: Ensure sustainable consumption and production patterns, which is key to sustaining the livelihoods of current and future generations. Additionally, converting mangosteen peels into MPP decreases the amount of agricultural waste disposed of in landfills, thereby reducing GHG emissions which are the primary driver of climate change, aligning with SDG 13: Take urgent action to combat climate change and its impacts

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

The topic addressed in this study is interesting and aligns well with the principles of sustainable development. However, there are critical methodological issues in the Life Cycle Assessment (LCA) section that must be addressed. Specifically, the LCA methodology lacks a clear definition of the functional unit and reference flow. The system boundaries are not properly defined or represented in the diagrams, which fail to indicate what processes are included, as well as the input and output flows. In the Life Cycle Inventory (LCI), there is no clear explanation of how the primary data were collected, nor are the sources or databases for secondary data identified. These issues must be resolved for the study to be scientifically robust and replicable.

The abstract should attract the reader's attention. As currently written, it does not clearly explain the importance of studying MPP. Within the framework of SDGs 12 and 13, the authors should briefly justify why MPP is studied over other products.

Throughout the manuscript, numerical data are reported with an excessive number of decimal places, such as a GWP value of 0.03072 in the abstract. The authors must report only significant figures, as this issue is recurrent and affects the clarity and professionalism of the document.

The use of “[22]” without identifying the author(s) makes it difficult for the reader to follow references. The authors should use a standard scientific format such as: “Joglekar et al. [22] evaluated the environmental impacts of hydrolysis...”. This format should be used consistently throughout the manuscript.

Lines 103–106: Stating the research questions verbatim is not optimal. The authors are advised to rephrase these as study objectives in narrative form to improve readability and scientific rigor.

Lines 119–120: The authors should include the precise geographical coordinates of the sampling or production site to improve the reproducibility of the study.

Line 148: The text currently describes a reference flow rather than a functional unit. The functional unit should express the function of the system. A more appropriate statement would be: “Processing of 1 kilogram of MPP”.

Figure 1 is a process flow diagram rather than a system boundary diagram. A proper LCA system boundary diagram must clearly delineate all processes considered within the life cycle inventory, including:

1. • Inputs to the system (materials, energy, etc.)
   • Outputs from the system (products, emissions, waste, etc.)
   • Whether upstream impacts from material and energy production are included
   • Whether emissions to air, water, and soil are quantified. This figure must be revised to correctly reflect the system boundaries.

Figure 3. Same observation as Figure 1. The authors must clearly define what is inside and outside the system boundaries and explicitly identify all inflows and outflows. This is currently a process flow diagram and not suitable for an LCA.

Section 2.2.2. This section focuses on primary data acquisition but does not mention secondary data sources. The authors must specify which database(s) were used for secondary data, such as Ecoinvent, Agri-footprint, Agrifood systems, etc.

Lines 189–191 – The authors mention the data values but do not describe how these data were collected. Was the data retrieved from process logs? Was it measured directly? If so, with what instruments? How was efficiency calculated? Which equations or assumptions were used?

Table 2. If all resources listed in Table 2 are from the same reference, it is unnecessary to include a reference column. Instead, the citation should be included in the table title.

 

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in green font.

Sincerely,

Alisa Soontornwat et al.

 

For easy visualization, the responses to the reviewer’s comments are provided below in green font.

Responses to the reviewers’ comments:

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

1. Theoretical implications must be presented before conclusion. The authors must discuss whether their findings are aligned with similar studies or not.
2. 2. Practical implications must be presented before conclusion.
3. 3. Managerial discussion must be presented before conclusion.
4. Finally, the main novelty must be mentioned in the abstract.

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in green font.

Sincerely,

Alisa Soontornwat et al.

 

For easy visualization, the responses to the reviewer’s comments are provided below in green font.

Responses to the reviewers’ comments:

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I don't think it has been revised properly according to my comments. The authors have to consider more detailed research boundaries and analyze the main environmental impacts.

Comments on the Quality of English Language

 The English could be improved to more clearly express the research.

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in green font.

Sincerely,

Alisa Soontornwat et al.

 

For easy visualization, the responses to the reviewer’s comments are provided below in green font.

Responses to the reviewers’ comments:

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

No further comments

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). 

Sincerely,

Alisa Soontornwat et al.

Round 3

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

 

1. The abstract succinctly summarizes the research but could benefit from a brief mention of the key findings regarding the optimal scheme (Scheme 6) and the preferred transportation strategy (Scenario B).
2. The introduction effectively sets the context by highlighting the significance of mangosteen peel waste and the need for sustainable valorization.
3. Consider adding a sentence or two about the novelty of the study, emphasizing the lack of prior research on GWP for MPP production.
4. The LCA methodology is well-explained, but the assumptions and limitations could be expanded. For example, clarify why health impacts and wastewater treatment were excluded.
5. The functional unit (1 kg of MPP) is appropriate, but justify why other potential functional units (e.g., per unit of bioactive compound) were not considered.
6. The methods for analyzing moisture content, water activity, α-mangostin, and microbial count are described in detail. However, include references for the AOAC method and other standardized protocols used.
7. Table 6 provides a useful summary of total GWP for each scheme and scenario. Consider adding a column with percentage differences to highlight the comparative advantages more clearly.
8. The results clearly show that Scheme 6 (frozen storage and hot air drying) is optimal in terms of GWP and product quality. Emphasize this finding in the discussion.
9. Expand on the practical challenges of implementing Scheme 6 and Scenario B in real-world settings, such as initial investment costs and scalability.
10. Address the discrepancy in GWP values for mangosteen production (1.71 vs. 0.89 kgCO2eq) mentioned earlier in the manuscript. Explain how this study's findings contribute to resolving such discrepancies.
11. The conclusions are well-supported by the results. Highlight the broader implications for sustainable agriculture and waste management.
12. The limitations section is thorough. For future research, consider suggesting specific renewable energy alternatives (e.g., solar-powered drying) and other agricultural wastes that could benefit from similar valorization approaches.

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in pink font.

Sincerely,

Alisa Soontornwat et al.

 

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

Based on my initial review, I suggested revising the scope and target of the environmental impact assessment. Regrettably, the second revision does not adequately address the comments provided. 

Author Response

Thank you very much for taking the time to review this manuscript (Manuscript ID: sustainability-3495973). Please find the detailed responses below. We have uploaded: (a) our point-by-point responses to comments by reviewers, and (b) an updated (revised) manuscript. For ease of identification, the revised text and new additions are in pink font.

Sincerely,

Alisa Soontornwat et al.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

At first, The research's boundaries and targets are unclear, and there is no concrete evidence or proper background to support the hypothesis.

The second point is that there is no relevant previous research survey. As a result, this paper could not show the research story and there is a lack of data collection. 

To explain why this research is focused on this case study, it is important to add additional information, such as the market share in domestic or worldwide markets. 

The figures 1 and 2 that you explained 6 schemes showed the emission to water and soil. That is, every process has an environmental impact on the air and river. However, you are only evaluating carbon dioxide in this research. It's challenging to find originality and academic value in the LCA results. 

In addition, this paper dealt with two scenarios on transportation. These scenarios are considering the distance and transportation methods by diesel truck. If you want to try a sensitivity analysis, you have to check the EV trucks. Furthermore, you also have to consider the electric power sources in the Thailand and the possibility of renewable energy.   

As a result, this paper's research conditions and results are currently very limited. At least, this paper should consider main environmental impacts based on proper hypothesis, data collection, and research boundaries to conclude relevant results using the LCA method.

Comments on the Quality of English Language

The English could be improved to express the research more clearly.

Reviewer 2 Report

Comments and Suggestions for Authors

The article explores six schemes for producing mangosteen peel powder (MPP) using Life Cycle Assessment (LCA) to evaluate their environmental impact in terms of Global Warming Potential (GWP) and product quality.

 

The introduction effectively highlights the problem of agricultural waste disposal, focusing on the mangosteen, and the importance of valorising its peels. The link to the UN Sustainable Development Goals (SDGs) is well articulated. However, expanding the context to show the global applicability of the case study would strengthen the relevance of the work. Furthermore, it would be useful to devote more space to the description of LCA as a useful tool to assess the environmental impacts of different processes and/or products as well, through appropriate references.

Suggestions:

• 10.1016/j.jclepro.2024.144174
• 10.3390/su142214828

 

The methodology clearly outlines the six MPP production schemes and two transportation scenarios. The details provided, including technical specifications and physical, chemical, and microbiological properties analysis, are commendable. However, excluding other environmental impacts, such as acidification potential and human toxicity, limits the study’s comprehensiveness.

I suggest clarifying the quality of the inventory data (primary, secondary or tertiary data, indicating the data source).

 

The discussion is well-connected to the results and reflects on optimizing drying processes to enhance sustainability.

However:

It could benefit from a broader comparison with other agricultural waste valorization technologies.

The potential for integrating renewable energy into the production processes is only briefly mentioned. A sensitivity analysis as the one made in 10.1016/j.jclepro.2024.144174 could be done for a proper discussion.

Reviewer 3 Report

Comments and Suggestions for Authors

1-     In the abstract, the authors did not address the contributions of this study and its advantages compared to other research works.

2-     The English language used is appropriate and clear, but needs minor revisions.

3-     Several studies have used DEA method and regression analysis. What is(are) the contribution(s) of this research?

4-     There is not enough justification for the usage of Tobit regression model. The authors should explain how come did they choose this method over many methods used for this purpose.

5-     The research questions should be given in the introduction section.

6-     The contributions of this research should be clearly explained in the introduction section.

7-     The literature review is too short.

8-     The literature review should be organized in a better manner so that similar studies are analyzed in one paragraph.

9-     A literature review table should be provided in the literature review section to clearly demonstrate the research gaps and the novelties of this study.

10-  The sampling data have not been thoroughly provided.

11-  The references for the benefits of DEA should be given in the manuscript.

12-  There is not enough discussion about the results.

13-  The outcomes should be compared with the similar studies.

14-  The practical implications and managerial discussions should be provided before conclusion.

 

15-  Suggestions for future research should be modified and extended.