Review Reports - Food Waste Valorization: Leveraging Singapore’s Zero Waste Master Plan and 30-by-30 Goal

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Food Waste Valorisation: Leveraging on Singapore’s Zero Waste Masterplan and 30-by-30 Goal

Abstract

· The abstract does not sufficiently summarize the key findings of the study. Include specific findings or results that highlight the main contributions of the paper. This provides readers with a quick understanding of what was discovered or concluded.

· The abstract lacks sufficient context or background information. Briefly describe the problem of food waste in Singapore and the relevance of the Zero Waste Masterplan and 30-by-30 Goal. This sets the stage for the reader, explaining why the study is necessary.

Introduction

· The introduction does not clearly state the specific research objectives or questions. Explicitly outline the primary research objectives or questions at the end of the introduction. Clearly defining the objectives will provide a focused direction for the paper and help readers understand the scope of the review.

· The introduction could better emphasize the significance and urgency of the study. Include a paragraph that underscores the importance of addressing food waste in the context of global sustainability challenges, economic impacts, and food security. Emphasize the potential benefits of successful food waste valorisation for environmental sustainability and economic growth.

· The introduction does not outline the structure of the paper. Include a brief roadmap of the paper’s structure at the end of the introduction. This will help readers navigate the paper and understand how each section contributes to the overall argument.

2.1 Food Wastage Statistics

· The section uses outdated or vague data points. Update the data with the most recent statistics available. Provide specific figures and their sources. Ensure that the data on food waste generated, disposed of, and recycled are the latest available.

2.2 Food Waste Recycling

· The section provides limited information on specific food waste recycling initiatives. Provide more details on the various recycling programs and initiatives implemented in Singapore. Describe specific recycling initiatives, such as community programs, government policies, and technological innovations.

· The section does not sufficiently address the challenges associated with food waste recycling. Discuss the main obstacles to increasing the food waste recycling rate and propose potential solutions. Identify and explain the challenges faced in food waste recycling, such as logistical issues, lack of public awareness, and economic barriers. Suggest ways to overcome these challenges, like public education campaigns or financial incentives for recycling.

· The section does not clearly link recycling efforts to their impact on waste management and sustainability goals. Explain how current recycling efforts contribute to broader sustainability and waste reduction goals. Connect the recycling efforts to their outcomes, such as reductions in landfill use or improvements in resource efficiency.

2.3 Food Waste Valorisation

· Provide a clear definition of food waste valorisation and its importance in waste management. Define valorisation clearly at the beginning of the section.

· The section lacks detailed descriptions of specific valorisation techniques. Provide more detailed explanations of the various techniques used for food waste valorisation in Singapore. Describe different valorisation methods, such as composting, anaerobic digestion, and the creation of bio-based products.

· The section does not include enough concrete examples or case studies of food waste valorisation. Incorporate specific case studies or examples to illustrate how food waste valorisation is being implemented effectively. Present case studies of successful valorisation projects, detailing the processes used and the outcomes achieved.

3.1 Okara

· The description of the valorisation processes for okara is too general. Include more detailed descriptions of the specific methods and processes used to convert okara into various products. Explain the scientific and technical steps involved in the fermentation and formulation processes.

· The section lacks performance metrics or results from studies on okara valorisation. Provide specific data or results from experiments or studies that demonstrate the effectiveness and efficiency of okara valorisation. Include metrics such as yield, nutrient content, and market potential.

3.2 Spent Barley Grain

· The section does not explain why spent barley grain (SBG) is a significant food waste stream to focus on. Provide a brief rationale for selecting SBG as a focus for food waste valorisation. Explain its availability and the potential for producing high-value products.

· The description of the valorisation processes for SBG is too general. Include more detailed descriptions of the specific methods and processes used to convert SBG into various products. Explain the scientific and technical steps involved in fermentation and protein extraction.

3.3 Fruits and Vegetable Wastes

· Provide a brief rationale for selecting fruits and vegetable wastes as a focus for food waste valorisation. Explain their abundance and the potential for producing high-value products.

4.1 Infrastructure Development

· The section does not provide enough information on the existing infrastructure for food waste valorisation. Describe the current infrastructure in place for food waste valorisation in Singapore. Include details on facilities, technologies, and capacities. This will give readers a clearer understanding of the starting point and the available resources for valorisation efforts.

· The section does not clearly identify the gaps in the current infrastructure. Identify the specific gaps and needs in the current infrastructure for effective food waste valorisation. Discuss what additional facilities, technologies, or capacities are required. Highlighting these gaps will underscore the challenges and guide future investments.

· The challenges related to investment in infrastructure are not thoroughly discussed. Discuss the financial challenges associated with investing in food waste valorisation infrastructure. Include potential solutions or strategies to attract investment. This will provide a more comprehensive view of the barriers and encourage stakeholders to consider funding opportunities.

4.2 Economic Viability

· Evaluate the economic viability of different valorisation techniques and provide a cost-benefit analysis. Include examples of successful economic models. This assessment will help stakeholders understand the financial benefits and potential returns on investment.

· Explore the market potential for products derived from food waste valorisation. Highlight potential markets and demand for these products. This will illustrate the economic opportunities and encourage investment in valorisation technologies.

4.3 Consumer Awareness

· Provide examples of successful consumer awareness campaigns related to food waste reduction and valorisation. Discuss the strategies used and their impact. This will offer practical insights and inspire similar initiatives.

4.4 Collaborative Partnerships

· The section does not discuss frameworks for facilitating collaboration. Discuss existing frameworks or models that facilitate collaboration in food waste valorisation. Suggest ways to enhance these frameworks to promote more effective partnerships. This will provide a blueprint for fostering cooperative efforts.

4.5 Regulatory Support

· The section does not propose specific regulatory improvements. Suggest specific regulatory changes or improvements that could support food waste valorisation. Discuss how these changes could facilitate innovation and growth in the sector. This will provide actionable recommendations for policymakers.

5.1 Legislation

· The section lacks a comprehensive overview of existing legislation related to food waste management in Singapore. Provide a detailed description of the current laws and regulations governing food waste management. Explain how these laws support or hinder food waste valorisation efforts. This will give readers a clearer understanding of the legal framework and its impact on food waste management.

· Identify and discuss any gaps or weaknesses in the current legislative framework that may impede effective food waste management and valorisation. Highlighting these gaps will underscore the challenges and guide future legislative improvements.

· Suggest specific legislative changes or improvements that could enhance food waste valorisation efforts. Discuss how these changes could provide better support for sustainable waste management practices. This will provide actionable recommendations for policymakers.

5.2 Initiatives Supporting Food Waste Management

· Describe in detail the various government initiatives and programs that support food waste management and valorisation. Highlight their objectives, strategies, and outcomes. This will give readers a comprehensive view of the support mechanisms available.

· Assess the impact and effectiveness of the various government initiatives in promoting food waste valorisation. Provide evidence or examples of successful outcomes. This evaluation will help in understanding the real-world impact of these programs.

· Highlight the importance of community involvement and public education in promoting food waste reduction and valorisation. Discuss specific community programs and their impact. This will show how public participation can enhance the effectiveness of waste management strategies.

· Suggest potential new initiatives or improvements to existing programs that could enhance food waste management and valorisation efforts. This will provide forward-looking recommendations to strengthen ongoing efforts.

· The section does not discuss how Singapore's initiatives compare to global best practices in food waste management. Compare Singapore’s initiatives with global best practices and discuss how international strategies could be adapted to improve local efforts. This comparison will provide insights into how Singapore can enhance its food waste management framework by learning from successful examples elsewhere.

Conclusions

· The conclusions section does not adequately summarize the key findings from the study. Clearly summarize the main findings from each section of the paper. This provides a concise overview of the study’s results and reinforces the key points.

· Identify areas where further research is needed and suggest specific topics or questions that future studies could address. This helps to guide ongoing research efforts and highlights the study’s contribution to the field.

· The conclusions do not include specific policy recommendations based on the study’s findings. Propose specific policy recommendations that could help improve food waste management and valorisation efforts. This provides actionable insights for policymakers.

· The section does not adequately connect the findings to the global context. Discuss how the findings relate to global food waste management challenges and solutions. This situates the research within a broader international framework.

· The section does not emphasize the need for stakeholder collaboration. Highlight the importance of collaboration between government, industry, and community stakeholders in addressing food waste challenges. This underscores the collective effort needed for effective food waste management.

Comments on the Quality of English Language

The writing quality in the provided document is generally clear and coherent, effectively conveying technical information.

Author Response

Thank you for your detailed review which would add a significant value to our paper. We have responded to each comment. The revised paper (additions in red) is attached.

Comments 1a (Abstract): The abstract does not sufficiently summarize the key findings of the study. Include specific findings or results that highlight the main contributions of the paper. This provides readers with a quick understanding of what was discovered or concluded.

Response 1a: Added statistics for Singapore’s % of imported foods and population, as well as updated the latest statistics for food waste generated in 2023. Elaborated on the food waste streams listed in the case studies of food waste valorization

Comments 1b (Abstract): The abstract lacks sufficient context or background information. Briefly describe the problem of food waste in Singapore and the relevance of the Zero Waste Masterplan and 30-by-30 Goal. This sets the stage for the reader, explaining why the study is necessary.

Response 1b: Added the definition of the Zero Waste Masterplan and 30-by-30 Goal.

Comments 2a (Introduction): The introduction does not clearly state the specific research objectives or questions. Explicitly outline the primary research objectives or questions at the end of the introduction. Clearly defining the objectives will provide a focused direction for the paper and help readers understand the scope of the review.

Response 2a: Added the objectives of the paper at the end of the introduction section.

Comments 2b (Introduction): The introduction could better emphasize the significance and urgency of the study. Include a paragraph that underscores the importance of addressing food waste in the context of global sustainability challenges, economic impacts, and food security. Emphasize the potential benefits of successful food waste valorisation for environmental sustainability and economic growth.

Response 2b: Added a paragraph to address this point in the beginning of the introduction section.

Comments 2c (Introduction): The introduction does not outline the structure of the paper. Include a brief roadmap of the paper’s structure at the end of the introduction. This will help readers navigate the paper and understand how each section contributes to the overall argument.

Response 2c: Added the roadmap of the paper’s structure at the end of the introduction section after stating the objectives. Added a paragraph on sustainable development goals at the end of the introduction section.

Comments 3 (Food waste statistics): The section uses outdated or vague data points. Update the data with the most recent statistics available. Provide specific figures and their sources. Ensure that the data on food waste generated, disposed of, and recycled are the latest available.

Response 3 (Food waste statistics): The data have been updated by including 2023 statistics.

Comments 4a (Food waste recycling): The section provides limited information on specific food waste recycling initiatives. Provide more details on the various recycling programs and initiatives implemented in Singapore. Describe specific recycling initiatives, such as community programs, government policies, and technological innovations.

Response 4a (Food waste recycling): Specific examples on recycling and upcycling initiatives have been added.

Comments 4b (Food waste recycling): The section does not sufficiently address the challenges associated with food waste recycling. Discuss the main obstacles to increasing the food waste recycling rate and propose potential solutions. Identify and explain the challenges faced in food waste recycling, such as logistical issues, lack of public awareness, and economic barriers. Suggest ways to overcome these challenges, like public education campaigns or financial incentives for recycling.

Response 4b (Food waste recycling): Detailed challenges and ways to address the challenges have been included.

Comments 4c (Food waste recycling): The section does not clearly link recycling efforts to their impact on waste management and sustainability goals. Explain how current recycling efforts contribute to broader sustainability and waste reduction goals. Connect the recycling efforts to their outcomes, such as reductions in landfill use or improvements in resource efficiency.

Response 4c (Food waste recycling): The above points are addressed under the challenges in food waste valorization and regulatory support section and subsections.

Comments 5a (Food waste valorisation): Provide a clear definition of food waste valorisation and its importance in waste management. Define valorisation clearly at the beginning of the section.

Response 5a (Food waste valorisation): Rearranged the order of the paragraphs within the section to address this point.

Comments 5b (Food waste valorisation): The section lacks detailed descriptions of specific valorisation techniques. Provide more detailed explanations of the various techniques used for food waste valorisation in Singapore. Describe different valorisation methods, such as composting, anaerobic digestion, and the creation of bio-based products.

Response 5b (Food waste valorisation): The review will not be focusing on lower value valorization but covering techniques that involves technology. Added some explanation on the processing flow of food waste valorization, i.e. treatment, bioreaction, extraction, purification, dehydration or concentration and formulation.

Comments 5c (Food waste valorisation): The section does not include enough concrete examples or case studies of food waste valorisation. Incorporate specific case studies or examples to illustrate how food waste valorisation is being implemented effectively. Present case studies of successful valorisation projects, detailing the processes used and the outcomes achieved.

Response 5c (Food waste valorisation): Some prototypes or solutions are tied up with Intellectual Properties (IPs). Detailed information on the IPs are not accessible. As much information as possible have been extracted from published sources.

Comments 6 (Okara): The description of the valorisation processes for okara is too general. Include more detailed descriptions of the specific methods and processes used to convert okara into various products. Explain the scientific and technical steps involved in the fermentation and formulation processes. The section lacks performance metrics or results from studies on okara valorisation. Provide specific data or results from experiments or studies that demonstrate the effectiveness and efficiency of okara valorisation. Include metrics such as yield, nutrient content, and market potential.

Response 6 (Okara): It is an IP product licensed to a private food tech company. However, it has not been commercialized as it is still undergoing pilot production trials. Hence, the detailed information are not accessible to the public.

Comments 7a (Spent barley grain): The section does not explain why spent barley grain (SBG) is a significant food waste stream to focus on. Provide a brief rationale for selecting SBG as a focus for food waste valorisation. Explain its availability and the potential for producing high-value products.

Response 7a (Spent barley grain): Added background information on the processing of SBG and its abundance in Singapore, and included statistics of SBG annually produced in Singapore.

Comments 7b (Spent barley grain): The description of the valorisation processes for SBG is too general. Include more detailed descriptions of the specific methods and processes used to convert SBG into various products. Explain the scientific and technical steps involved in fermentation and protein extraction.

Response 7b (Spent barley grain): The information on the scientific and technical steps is limited as it was not revealed in the paper. The reference is included next to the case studies if the reader intends to find out more.

Comments 8 (Fruits and Vegetable Wastes): Provide a brief rationale for selecting fruits and vegetable wastes as a focus for food waste valorisation. Explain their abundance and the potential for producing high-value products.

Response 8 (Fruits and Vegetable Wastes): Added the reason for their abundance and potential for producing high-value products. However, there is no local statistics available for fruit and vegetable wastes.

Comments 9a (Infrastructure development): The section does not provide enough information on the existing infrastructure for food waste valorisation. Describe the current infrastructure in place for food waste valorisation in Singapore. Include details on facilities, technologies, and capacities. This will give readers a clearer understanding of the starting point and the available resources for valorisation efforts.

Response 9a (Infrastructure development): Current infrastructure e.g. the Nexus and the technology involved are added.

Comments 9b (Infrastructure development): The section does not clearly identify the gaps in the current infrastructure. Identify the specific gaps and needs in the current infrastructure for effective food waste valorisation. Discuss what additional facilities, technologies, or capacities are required. Highlighting these gaps will underscore the challenges and guide future investments.

Response 9b (Infrastructure development): The technology and infrastructure gaps are identified and elaborated.

Comments 9c (Infrastructure development): The challenges related to investment in infrastructure are not thoroughly discussed. Discuss the financial challenges associated with investing in food waste valorisation infrastructure. Include potential solutions or strategies to attract investment. This will provide a more comprehensive view of the barriers and encourage stakeholders to consider funding opportunities.

Response 9c (Infrastructure development): Financial challenges and proposed solutions are included.

Comments 10a (Economic viability): Evaluate the economic viability of different valorisation techniques and provide a cost-benefit analysis. Include examples of successful economic models. This assessment will help stakeholders understand the financial benefits and potential returns on investment.

Response10a (Economic viability): No data from the cost-benefit analysis is available from Singapore as food waste valorisation is still new here. However, it is highlighted that food waste valorisation opens new revenue for the industry.

Comments 10b (Economic viability): Explore the market potential for products derived from food waste valorisation. Highlight potential markets and demand for these products. This will illustrate the economic opportunities and encourage investment in valorisation technologies.

Comments 10b (Economic viability): Market potential for valorised food waste is highlighted.

Comments 11 (Consumer awareness): Provide examples of successful consumer awareness campaigns related to food waste reduction and valorisation. Discuss the strategies used and their impact. This will offer practical insights and inspire similar initiatives.

Response 11 (Consumer awareness): Consumer awareness campaign and its related strategies are added.

Comments 12 (Collaborative partnerships): The section does not discuss frameworks for facilitating collaboration. Discuss existing frameworks or models that facilitate collaboration in food waste valorisation. Suggest ways to enhance these frameworks to promote more effective partnerships. This will provide a blueprint for fostering cooperative efforts.

Response 12 (Collaborative partnerships): A more detailed collaboration between institutions, government, community and private sectors are highlighted.

Comments 13 (Regulatory support): The section does not propose specific regulatory improvements. Suggest specific regulatory changes or improvements that could support food waste valorisation. Discuss how these changes could facilitate innovation and growth in the sector. This will provide actionable recommendations for policymakers.

Response 13a (Regulatory support): Suggestion on a better regulatory support with reference to case studies from other countries is included. The expected outcomes on innovation and growth in the sector are proposed. Recommendations for policymakers to promote food waste valorisation in the country have also been made.

Comments 14a (Legislation): The section lacks a comprehensive overview of existing legislation related to food waste management in Singapore. Provide a detailed description of the current laws and regulations governing food waste management. Explain how these laws support or hinder food waste valorisation efforts. This will give readers a clearer understanding of the legal framework and its impact on food waste management.

Response 14a (Legislation): Enhancement on existing legislation and comments on the gaps of this framework are covered in subsequent paragraphs.

Comments 14b (Legislation): Identify and discuss any gaps or weaknesses in the current legislative framework that may impede effective food waste management and valorisation. Highlighting these gaps will underscore the challenges and guide future legislative improvements.

Response14b (Legislation): Examples on scope of legislation, enforcement and compliance, economic incentives, public awareness and behaviour changes are added.

Comments 14c (Legislation): Suggest specific legislative changes or improvements that could enhance food waste valorisation efforts. Discuss how these changes could provide better support for sustainable waste management practices. This will provide actionable recommendations for policymakers.

Response 14c (Legislation): Suggestions to help closing the gaps and weaknesses are added.

Comments 15a (Initiatives Supporting Food Waste Management): Describe in detail the various government initiatives and programs that support food waste management and valorisation. Highlight their objectives, strategies, and outcomes. This will give readers a comprehensive view of the support mechanisms available.

Response 15a (Initiatives Supporting Food Waste Management): Details, objectives, strategies and outcomes for each of the initiatives the Singapore government hosted have been previously stated and further enhanced in this version.

Comments15b (Initiatives Supporting Food Waste Management): Assess the impact and effectiveness of the various government initiatives in promoting food waste valorisation. Provide evidence or examples of successful outcomes. This evaluation will help in understanding the real-world impact of these programs.

Response 15b (Initiatives Supporting Food Waste Management): Providing successful outcomes would mean including the names of startups and their collaborators. To prevent the paper from sounding bias, a general description of the successful outcomes have been included.

Comments 15c (Initiatives Supporting Food Waste Management): Highlight the importance of community involvement and public education in promoting food waste reduction and valorisation. Discuss specific community programs and their impact. This will show how public participation can enhance the effectiveness of waste management strategies.

Response 15c (Initiatives Supporting Food Waste Management): Community programs such as 'Say YES to Waste Less' campaign are included with examples and outcomes.

Comments 15d (Initiatives Supporting Food Waste Management): Suggest potential new initiatives or improvements to existing programs that could enhance food waste management and valorization efforts. This will provide forward-looking recommendations to strengthen ongoing efforts.

Response 15d (Initiatives Supporting Food Waste Management): Examples of new initiatives are added.

Comments 15e (Initiatives Supporting Food Waste Management): The section does not discuss how Singapore's initiatives compare to global best practices in food waste management. Compare Singapore’s initiatives with global best practices and discuss how international strategies could be adapted to improve local efforts. This comparison will provide insights into how Singapore can enhance its food waste management framework by learning from successful examples elsewhere.

Response 15e (Initiatives Supporting Food Waste Management): Examples from China and South Korea have been included for better insights on how Singapore can improve on food waste management.

Comments 16a (Conclusions): The conclusions section does not adequately summarize the key findings from the study. Clearly summarize the main findings from each section of the paper. This provides a concise overview of the study’s results and reinforces the key points.

Response 16a (Conclusions): Main points from each section are included.

Comments 16b (Conclusions): Identify areas where further research is needed and suggest specific topics or questions that future studies could address. This helps to guide ongoing research efforts and highlights the study’s contribution to the field.

Response16b (Conclusions): Suggestions for future studies are included.

Comments16c (Conclusions): The conclusions do not include specific policy recommendations based on the study’s findings. Propose specific policy recommendations that could help improve food waste management and valorisation efforts. This provides actionable insights for policymakers.

Response16c (Conclusions): Policy recommendations as described in the main text are summarized and included.

Comments16d (Conclusions): The section does not adequately connect the findings to the global context. Discuss how the findings relate to global food waste management challenges and solutions. This situates the research within a broader international framework.

Response16d (Conclusions): The paper is to review the food waste valorisation in Singapore. Therefore, relating Singapore’s scenario to global food waste management is considered not in the scope. However, reference to China and South Korea for best practices have been included in the main text.

Comments 16e (Conclusions): The section does not emphasize the need for stakeholder collaboration. Highlight the importance of collaboration between government, industry, and community stakeholders in addressing food waste challenges. This underscores the collective effort needed for effective food waste management.

Response16e (Conclusions): The collaboration is highlighted.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Singapore is a modern developed country with a lot of successful experience in national management, inculding Food Waste Valorisation. This manuscript provided a thorough review on food waste status in Singapore, food waste valorisation in Singapore and summarizes the challenges in Food Waste Valorization. The review can provide solutions for other countries in ensuring food security and achieving sustainable development goals. In my opinion, the manuscript does have the quality to be published on Sustainability, however, major revison is necessary. The main limits are list below:

1. Figure 1: authors should provide the data of the world simultaneously, and give a general comparison.

2. “4. Challenges in Food Waste Valorization” part, the challenges shoud be classified， such as Government policies,science and technology, public quality, etc., and then analysis the current solution and provide the suggestions.

Author Response

Comment 1: Singapore is a modern developed country with a lot of successful experience in national management, inculding Food Waste Valorisation. This manuscript provided a thorough review on food waste status in Singapore, food waste valorisation in Singapore and summarizes the challenges in Food Waste Valorization. The review can provide solutions for other countries in ensuring food security and achieving sustainable development goals. In my opinion, the manuscript does have the quality to be published on Sustainability, however, major revison is necessary. The main limits are list below:

Figure 1: authors should provide the data of the world simultaneously, and give a general comparison.

Response 1: The comment is well-taken note. To clarify, the subsection only provides a review on the food waste management data in Singapore, to be in line the objectives of the paper. However, within the scope of the paper, further sections do incorporate perspectives on the valorization of food waste from other countries.

Comment 2: “4. Challenges in Food Waste Valorization” part, the challenges shoud be classified， such as Government policies,science and technology, public quality, etc., and then analysis the current solution and provide the suggestions."

Response 2: The section have been amended to incorporate the present scenario and ideas for improvement in the subsection “Infrastructure development” and “Regulatory support”. The classification in this paper categorizes government policies as "Regulatory support," science and technology as "Infrastructure management," and public quality as "Economy viability" and "Consumer awareness." These categories are deemed more particular and pertinent to the valorisation of food waste.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I think it can be accepted in the current state.