Understanding Food Waste Sorting Practices: Insights from a Systematic Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments to the Authors:

Thank you for the work you have done. However, I think some improvements should be made to better justify the results and the conclusions ultimately reached. Before accepting this manuscript, I think it needs at least major revisions.

 

1. The authors review global research on food waste sorting. The authors should place the context internationally, not just in Europe.

 

2. Recently, several studies have systematically reviewed the influencing factors affecting the sorting of domestic or food waste. The authors should review these studies and emphasize the new contribution of this paper.

 

3. It is better to add a flowchart to summarize the literature search process.

 

4. As it stands, the authors still overlooked some literature on similar topics during the search process. It is recommended that the authors carry out the search again to ensure the completeness of the search results.

 

5. Existing studies have used different methods, such as multiple regression, qualitative comparative analysis, and textual analysis. It is better to review the methods used in previous studies.

 

6. The Theory of Planned Behavior has been widely applied to household waste recycling behavior. However, many different theories have been used in previous studies. It is better to briefly review the other theories.

 

7. The authors review many existing studies. I suggest that the authors add a section of future research directions to help provide some suggestions for subsequent scholars.

 

8. Check the formatting of the full manuscript, e.g. line 126.

 

9. Check references, e.g., journal name for reference [59].

Author Response

 

Comments 1: The authors review global research on food waste sorting. The authors should place the context internationally, not just in Europe.

Response 1: Thank You for your comment. The revised version of the manuscript clarifies that the study examines food waste sorting from a global perspective, not just within Europe. While European policies and regulations are referenced as key examples, the literature review includes research from various regions, including North America, Asia, and other global contexts. The discussion has been expanded to ensure a more comprehensive representation of international waste sorting practices and policies.

 

Comments 2: Recently, several studies have systematically reviewed the influencing factors affecting the sorting of domestic or food waste. The authors should review these studies and emphasize the new contribution of this paper.

Response 2: Thank You for your comment. In response, we have thoroughly reviewed recent systematic studies on food waste sorting and incorporated 12 additional handpicked studies to ensure a comprehensive analysis of the latest research. However, we acknowledge that not all relevant studies are currently accessible due to availability constraints.

Furthermore, while existing reviews primarily focus on behavioral and environmental perspectives, this study distinguishes itself by emphasizing the economic dimension of food waste sorting. Our analysis explores financial incentives, cost-effectiveness, and economic mechanisms driving household participation, providing a unique contribution to literature. The study aims to bridge the gap between behavioral theories and economic policy applications, offering practical insights for policymakers and waste management strategies.

 

Comments 3: It is better to add a flowchart to summarize the literature search process.

Response 3: Thank You for your comment. A flowchart summarizing the literature search process has been included in the manuscript to provide a clear and structured overview of the systematic review methodology. This visual representation enhances transparency in the selection process, demonstrating how studies were identified, screened, and included in the final analysis.

 

Comments 4: As it stands, the authors still overlooked some literature on similar topics during the search process. It is recommended that the authors carry out the search again to ensure the completeness of the search results.

Response 4: Thank You for your comment. To ensure a comprehensive review, we conducted an extensive literature search following a systematic methodology. Additionally, to enhance the completeness of the search results, we manually identified and included 12 additional relevant studies that were not initially retrieved through database searches. These additional studies were carefully selected to complement the existing body of literature, particularly in addressing the economic perspective of food waste sorting. However, we acknowledge that access to some studies remains limited due to paywall restrictions, which is a common challenge in systematic reviews.

Given the breadth of existing research on waste sorting behaviors, our approach focused on the most relevant and recent contributions, ensuring a robust and representative sample of studies. We believe that the included literature sufficiently reflects the current state of research in this field and supports the study’s primary objective.

 

Comments 5: Existing studies have used different methods, such as multiple regression, qualitative comparative analysis, and textual analysis. It is better to review the methods used in previous studies.

Response 5: Thank You for your comment. In response to the comment, we have expanded the discussion on research methodologies used in previous studies on food waste sorting behaviors. The revised section now provides a more detailed overview of both quantitative and qualitative approaches. These include multiple regression analysis, structural equation modeling (SEM), and meta-analysis, which allow for testing causal relationships between psychological and socio-demographic factors. Additionally, we discuss qualitative comparative analysis (QCA) and textual analysis, which help uncover individual and cultural perceptions of waste management practices that may not be captured through surveys and experiments. This revision ensures that the study reflects a more comprehensive understanding of methodological diversity in food waste behavior research.

 

Comments 6: The Theory of Planned Behavior has been widely applied to household waste recycling behavior. However, many different theories have been used in previous studies. It is better to briefly review the other theories.

Response 6: Thank You for your comment. We acknowledge that the Theory of Planned Behavior (TPB) is one of the most widely used frameworks for analyzing household waste sorting behavior. However, to provide a more comprehensive review, we have included a discussion of alternative theoretical models used in previous studies. The Theory of Reasoned Action (TRA) is presented as the foundation for TPB, explaining how attitudes and subjective norms influence behavioral intentions. Additionally, we discuss the Norm Activation Model (NAM), which emphasizes moral norms and personal responsibility, and the Value-Belief-Norm (VBN) Theory, which links pro-environmental behavior to broader altruistic and biospheric values. These theoretical perspectives offer valuable insights into different motivational factors influencing waste sorting behavior, especially in contexts where ethical and moral considerations play a key role. This addition strengthens the theoretical background of our study and highlights the diversity of approaches in the field.

 

Comments 7: The authors review many existing studies. I suggest that the authors add a section of future research directions to help provide some suggestions for subsequent scholars.

Response 7: Thank You for your comment. The study includes a dedicated section outlining future research directions, addressing key gaps identified in the existing literature. The recommendations focus on expanding the scope of food waste sorting research by incorporating economic incentives, behavioral interventions, and technological advancements. Additionally, the study suggests further exploration of cross-cultural differences, longitudinal studies to assess behavioral change over time, and interdisciplinary approaches integrating psychology, economics, and policy studies. These detailed suggestions aim to guide future scholars in developing more comprehensive and effective waste management strategies.

 

Comments 8: Check the formatting of the full manuscript, e.g. line 126.

Response 8: Thank You for your comment. The full manuscript has been carefully reviewed, and formatting issues, including those around line 126, have been checked and corrected. Adjustments have been made to ensure consistency in citation styles, section headings, tables, and figures, aligning with the required formatting guidelines.

 

Comments 9: Check references, e.g., journal name for reference [59].

Response 9: Thank You for your comment. The references, including journal names, citation formats, and consistency, have been thoroughly reviewed. Any errors or inconsistencies, including those in reference [59], have been corrected to ensure accuracy and adherence to the required citation style.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is well-structured, but some issues need to be addressed. It is recommended that its quality be improved based on the following comments.

 (1)   In Table 3, the waste food classification only takes into account the solid state. Is it necessary to consider the liquid state as well? This would make the analysis more comprehensive.

(2)   In line 168, the author did not analyze the relevant content of the literature in detail, nor the research focus, including the impact of the research content on food classification. Instead, the author directly proposed to conduct literature research from the economic and policy aspects. Personally, I feel that the research is not objective or persuasive enough, and it fails to fully reflect the current research status of food classification.

(3)   In line 208, will we stop researching just because it’s not open - source? This will lead to inaccuracies in the research.

(4)   In line 220, what is the conclusion? Please elaborate in detail.

(5)   In line 268, I think the literature on residents' garbage - sorting behaviors has been summarized, but the research value of these documents has not been presented. That is, what problems these literatures have addressed or what functions they have served are not specified.

(6)   In line 286, what is the full name of TRA? What does it mean? Why use this theory? Can't TPB (Theory of Planned Behavior) analyze the influencing factors of food waste classification well?

(7)   Section 5.3 lists the literature related to users' behaviors and motivations regarding food waste, but it does not provide a summary and evaluation, which needs to be elaborated. Such problems exist in the subsequent summaries as well.

In summary, it is proposed that the paper be accepted with major modifications.

Author Response

 

Comments 1: In Table 3, the waste food classification only takes into account the solid state. Is it necessary to consider the liquid state as well? This would make the analysis more comprehensive.

Response 1: Thank You for your comment. The classification in Table 3 primarily focuses on solid food waste because it constitutes most household food waste sorting practices. While liquid waste, such as used cooking oil, is collected separately in some regions, its management and sorting processes significantly differ from solid food waste. Given that the primary focus of this study is on household food waste sorting and economic implications, the inclusion of liquid waste was deemed less relevant. However, future research could explore the economic and logistical aspects of liquid food waste management in greater depth.

 

Comments 2: In line 168, the author did not analyze the relevant content of the literature in detail, nor the research focus, including the impact of the research content on food classification. Instead, the author directly proposed to conduct literature research from the economic and policy aspects. Personally, I feel that the research is not objective or persuasive enough, and it fails to fully reflect the current research status of food classification.

Response 2: Thank You for your comment. The section in line 168 has been revised to provide a more detailed analysis of the relevant literature, including a clearer discussion of the research focus and its implications for food classification. The updated content now better reflects the current state of research on food waste sorting by incorporating findings on both technological and behavioral aspects, as well as their economic and policy implications. This revision ensures a more balanced and comprehensive perspective, strengthening the objectivity and persuasiveness of the study.

 

Comments 3: In line 208, will we stop researching just because it’s not open - source? This will lead to inaccuracies in the research.

Response 3: Thank You for your comment. The research was conducted using a large and diverse sample of studies to ensure comprehensive analysis. However, due to institutional access limitations, paywalled articles were not included in the review. While this may exclude some studies, the broad scope of open-access literature analyzed provides a strong foundation for drawing reliable conclusions. Moreover, efforts were made to include high-quality and relevant sources, ensuring that the research findings remain robust and reflective of current knowledge in the field.

 

Comments 4: In line 220, what is the conclusion? Please elaborate in detail.

Response 4: Thank You for your comment. The conclusion drawn from the multi-criteria analysis is that research on food waste sorting has significantly increased in recent years, particularly after 2015, reflecting growing academic and policy interest in the topic. The analysis also highlights geographic disparities in research focus, with a significant concentration of studies conducted in China and Europe, while other regions, such as low- and middle-income countries, remain underrepresented.

Additionally, the reviewed studies predominantly rely on statistical data analysis, often using behavioral theories such as the Theory of Planned Behavior (TPB) to explain sorting behaviors. However, methodological diversity exists, with some studies employing modeling techniques, qualitative research, and experimental interventions. The results suggest that while external incentives such as regulations and financial measures effectively increase compliance, long-term behavioral change is driven by intrinsic motivation, social norms, and environmental awareness.

These findings underscore the need for future research to focus on regions with limited empirical data, explore interdisciplinary approaches, and assess the long-term impacts of policy measures on food waste sorting behaviors.

 

Comments 5: In line 268, I think the literature on residents' garbage - sorting behaviors has been summarized, but the research value of these documents has not been presented. That is, what problems these literatures have addressed or what functions they have served are not specified.

Response 5: Thank You for your comment. The reviewed literature on residents' garbage-sorting behaviors has addressed several key research gaps and practical challenges. These studies have primarily focused on identifying the psychological, social, and economic factors influencing waste sorting behaviors, providing insights into how policy interventions, financial incentives, and community engagement can enhance waste management effectiveness.

The research serves several key functions:

1. Understanding Behavioral Motivations – Many studies analyze why individuals choose to participate (or not) in waste sorting, examining factors such as environmental awareness, convenience, financial incentives, and social norms. This helps policymakers design targeted interventions that encourage sorting behaviors.
2. Evaluating Policy Effectiveness – Several studies assess the impact of existing waste management policies, such as pay-as-you-throw schemes, mandatory sorting regulations, and deposit-refund systems. These evaluations provide empirical evidence on what policy measures are most effective in driving waste separation.
3. Exploring Socioeconomic and Regional Variations – The literature highlights how cultural and socioeconomic factors influence waste sorting behavior. For example, studies from China emphasize policy-driven compliance, whereas research in Europe often focuses on voluntary participation motivated by environmental concern.
4. Advancing Methodological Approaches – The studies reviewed employ diverse methodologies, including quantitative statistical analysis, behavioral experiments, and qualitative comparative analysis. This allows researchers to assess different aspects of waste sorting behavior and refine theoretical models such as the Theory of Planned Behavior (TPB).

By synthesizing these studies, the research contributes to a comprehensive understanding of waste sorting behavior, providing a basis for future studies to explore long-term behavioral changes, regional differences, and the effectiveness of emerging waste management strategies.

 

Comments 6: In line 286, what is the full name of TRA? What does it mean? Why use this theory? Can't TPB (Theory of Planned Behavior) analyze the influencing factors of food waste classification well?

Response 6: Thank You for your comment. TRA stands for the Theory of Reasoned Action, developed by Fishbein and Ajzen (1975). This theory suggests that an individual’s behavior is primarily driven by their intention, which in turn is influenced by their attitudes and subjective norms. However, TRA assumes that people have full volitional control over their actions, meaning it does not account for external constraints that may prevent individuals from performing a particular behavior.

In contrast, the Theory of Planned Behavior (TPB) expands on TRA by incorporating perceived behavioral control, which acknowledges that external factors—such as infrastructure, financial constraints, or policy enforcement—can impact behavior. This makes TPB more applicable to real-world contexts, including food waste classification, where external barriers (e.g., lack of access to sorting facilities, unclear policies, or social pressure) significantly influence participation.

While TPB is widely used to analyze waste sorting behaviors, TRA remains valuable in understanding behaviors that are primarily driven by intrinsic motivation and social norms, such as voluntary waste reduction efforts or environmentally conscious decisions made in the absence of strict regulations. The integration of both theories allows for a more comprehensive analysis, distinguishing between behaviors influenced by internal motivations (TRA) and those shaped by external conditions (TPB).

 

Comments 7: Section 5.3 lists the literature related to users' behaviors and motivations regarding food waste, but it does not provide a summary and evaluation, which needs to be elaborated. Such problems exist in the subsequent summaries as well.

Response 7: Thank You for your comment. The sections listing literature on users' behaviors and motivations regarding food waste have been revised to include summaries and evaluations of the key findings. Each study’s contribution, research focus, and relevance to food waste sorting behavior have been clarified to provide a more comprehensive and analytical overview.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

The paper examines the factors influencing the efficiency of sorting food waste within municipalities. The relevance of the study is due to the significant amounts of food waste generated annually, the need for their efficient processing, as well as the orientation of national economies towards sustainable and "green" development. The authors carried out an analysis of scientific publications in this field, on the basis of which they determined the crucial role of financial incentives and infrastructural solutions, as well as internal awareness of the environment and social norms in shaping behavior when sorting food waste. Planned behavior theory (TPB) as well as socio-cognitive theory (SCT) were used as a research tool to study sorting behavior. The results highlight the differences in sorting practices in different regions. The results obtained indicate the need to intensify research in this field, as well as to organize an international exchange of knowledge and best practices in this field, which will significantly advance the achievement of the principles of a "green" economy. In this regard, I would like to make several recommendations to improve the quality of the presented results. 1) I recommend making a note in Figure 1, reflecting that the data for 2024 is not presented for the entire year (the data slice was made for the month of March). Otherwise, you get the impression that there is a negative trend. 2) The introduction mentions the existence of new requirements for the sorting of food waste (line 10). If we are talking about the availability of legislative acts, then their development is usually based on the study of best practices in this area. It would be useful to provide information on the basis of which scientific studies (publications of their results) these documents were developed. 3) The absence of publications on the research topic in the period preceding 2000 may not indicate the absence of such studies as such, but rather their publication in journals that are not indexed in these databases. One example of a country with an effective waste sorting system is Japan, but there are not many publications on this topic in the sample. The article is practical in nature and will be useful to both the academic and business communities, as well as municipal and regional authorities.

Author Response

 

Comments 1: I recommend making a note in Figure 1, reflecting that the data for 2024 is not presented for the entire year (the data slice was made for the month of March). Otherwise, you get the impression that there is a negative trend.

Response 1: Thank You for your comment. A clarification has been added to Figure 1, specifying that the 2024 data represents only the period up to March. This adjustment ensures that readers do not misinterpret the data as indicating a negative trend for the full year.

 

Comments 2: The introduction mentions the existence of new requirements for the sorting of food waste (line 10). If we are talking about the availability of legislative acts, then their development is usually based on the study of best practices in this area. It would be useful to provide information on the basis of which scientific studies (publications of their results) these documents were developed.

Response 2: Thank You for your comment. A clarification has been added to the Introduction, specifying that the development of legislative acts for food waste sorting has been informed by scientific research, best practices, and policy evaluations. References to relevant studies and policy assessments have been included to illustrate the empirical basis for these regulations.

 

Comments 3: The absence of publications on the research topic in the period preceding 2000 may not indicate the absence of such studies as such, but rather their publication in journals that are not indexed in these databases. One example of a country with an effective waste sorting system is Japan, but there are not many publications on this topic in the sample.

Response 3: Thank You for your comment. A clarification has been added to the text, acknowledging that the absence of publications before 2000 does not necessarily indicate a lack of research but may be due to limitations in database indexing. Additionally, the case of Japan’s waste sorting system has been noted, emphasizing that while Japan has an established waste management framework, fewer studies on the topic were retrieved in the systematic search, potentially due to language barriers or publication in non-indexed sources.

 

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

1. It is preferable not to place literature references in the abstract.

 

2. Authors need to thoroughly check the names of journals corresponding to all literature. For example, literature [21] was published in the Journal of Cleaner Production, not Waste Management; literature [46] was published in the Journal of Environmental Management, not Resources, Conservation & Recycling; and [72] was published in Environmental Impact Assessment Review, not Waste Management. The authors cited many references, however, a large proportion of the literature corresponded to incorrect journal titles. Accordingly, the statistical conclusions in Table 7 may be wrong.

Author Response

Comments 1: It is preferable not to place literature references in the abstract.

Answer 1: Thank You for your comment. All literature references have been removed from the abstract.

Comments 2: Authors need to thoroughly check the names of journals corresponding to all literature. For example, literature [21] was published in the Journal of Cleaner Production, not Waste Management; literature [46] was published in the Journal of Environmental Management, not Resources, Conservation & Recycling; and [72] was published in Environmental Impact Assessment Review, not Waste Management. The authors cited many references, however, a large proportion of the literature corresponded to incorrect journal titles. Accordingly, the statistical conclusions in Table 7 may be wrong.

Answer 2: Thank You for your comment. Considering your comments, the entire reference list has been thoroughly reviewed to ensure accurate primary publication sources for all articles. Additionally, references have been supplemented with DOI links where possible. Accordingly, Table 4 has been adjusted to include DOI-based references, and Table 7 along with its conclusions has been revised.

Reviewer 2 Report

Comments and Suggestions for Authors

No comments

Author Response

Thank you for your evaluation and valuable feedback. Your insights are very important and help us achieve the best results.