Quantitative and Qualitative Characterization of Food Waste for Circular Economy Strategies in the Restaurant Sector of Riobamba, Ecuador: A Case Study Approach

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript "Quantifying and Characterizing Food Waste for Circular Economy Strategies in the Restaurant Sector of Riobamba, Ecuador: A Case Study Approach" described the food waste scenario in Riobamba, Ecuador. The research design, data collection, and analysis are fine considering the merit of publication. However, the sample size is limited, and the discussion section needs much improvement. I have some questions/suggestions that need to be addressed before the final evaluation of this manuscript. 

1. The sample size is to small too be considered practical for extrapolation to represent the food industry. How can it be justified?
2. I suggest making the sample size appropriate and providing a table of the total number of restaurants in the area under investigation, contacted by the researcher and agreed to take part. provide the proportionality factor is really understand the situation. 
3. There are some editing/grammar mistakes, such as page 2 line 93; remove the same in "ad ult.". Similarly, check the whole manuscript thoroughly.
4. Page 4 line 174; check "à la carte dishes" Is it an accurate word? I am confused; may be it is some local terminology. 
5. Table 1. Data is for seven days from Monday to Sunday, whereas in text it is mentioned Monday to Friday (line 247). Correct it accordingly.
6. Improve the discussion section with reference to the published literature. Compared the results obtained with already published data.
7. References are poorly managed. The data is missing, such as article number is missing in the very first reference in References (bibliography). Similarly, Ref. 8-10 is not properly provided. If these are web links, provide the link address properly. Similarly, Ref. 15, 17, and so on
8. Check all the reference lists and correct accordingly, following the journal guidelines.

Author Response

Comments 1: The sample size is to small too be considered practical for extrapolation to represent the food industry. How can it be justified?

Response 1: Although the sample size of 13 restaurants might seem small, it is in line with other research in the area of characterizing and quantifying food waste. To characterize waste streams and investigate biorefinery technologies, for example, Carmona-Cabello et al. (2020) studied food waste from the restaurant sector using a sample of just four Italian restaurants. Similarly, Hidalgo Crespo et al. (2022) characterized restaurant waste and evaluated its potential for energy generation within a circular economy framework using a sample of 13 restaurants in Guayaquil, Ecuador. These studies show that even tiny, well-chosen samples can provide insightful information.

The current study uses a case study methodology, concentrating on the restaurants in Riobamba to give a thorough grasp of the makeup of food waste and its possible uses in the circular economy. Practical factors such as accessibility, desire to participate, and the representativeness of various restaurant types (such as fast food, seasonal menus, and menu-based dishes) were considered while determining the sample size. Furthermore, the main goal of this study is to create a baseline for measuring and describing food waste in a local context rather than extrapolating results to the entire food sector. This method offers practical insights for customized waste management strategies and is consistent with the exploratory nature of the study.

The sample's results provide vital information on the composition of food waste, including its moisture content, ash content, pH, and other physicochemical characteristics, for developing solutions for the circular economy.

 

Comments 2: I suggest making the sample size appropriate and providing a table of the total number of restaurants in the area under investigation, contacted by the researcher and agreed to take part. provide the proportionality factor is really understand the situation. 

Response 2: Regarding the sample size and transparency in the sampling process, we would like to explain that, according to local tourism registries, there are 85 registered tourist restaurants in Riobamba (this information will be attached as a Supplementary File). Of these, 13 restaurants initially contacted through collaboration with the Ministry of Tourism, expressed interest in participating by allowing trainees from the Gastronomy School to collect data while assisting as temporary employees and meet the inclusion criteria. (1) Located within the municipal boundaries of Riobamba. (2) Engaged in the preparation and service of food to customers. (3) Provided consent to participate in the observational study and granted access to their premises for data collection purposes. (4) Demonstrated willingness to accept a student from the local Gastronomy school as part of their internship cycle, allowing for hands-on instruction and experiential learning in restaurant operations.

This corresponds to a participation rate of 15.3% of the total registered restaurants.

Sample in the methods section has been updated

 

Comments 3: There are some editing/grammar mistakes, such as page 2 line 93; remove the same in "ad ult.". Similarly, check the whole manuscript thoroughly.

Response 3: It has been reviewed and updated

 

 

Comments 4: Page 4 line 174; check "à la carte dishes" Is it an accurate word? I am confused; maybe it is some local terminology. 

Response 4: Thank you for your suggestion. We assumed "à la carte dishes" was widely understood as it refers to individually ordered dishes. However, to ensure clarity, we have replaced it with "menu-based dishes" throughout the manuscript.

 

Comments 5: Table 1. Data is for seven days from Monday to Sunday, whereas in text it is mentioned Monday to Friday (line 247). Correct it accordingly.

Response 5: It has been updated

 

Comments 6: Improve the discussion section with reference to the published literature. Compared the results obtained with already published data.

Response 6: It section has been improve in the manuscript

 

Comments 7: References are poorly managed. The data is missing, such as article number is missing in the very first reference in References (bibliography). Similarly, Ref. 8-10 is not properly provided. If these are web links, provide the link address properly. Similarly, Ref. 15, 17, and so on

Response 7: We thank the reviewer for pointing out the issues with the references. We have thoroughly reviewed and revised all entries in the References section to ensure compliance with the required formatting standards.

 

Comments 8: Check all the reference lists and correct accordingly, following the journal guidelines.

Response 8: We thank the reviewer for pointing out the issues with the references. We have thoroughly reviewed and revised all entries in the References section to ensure compliance with the required formatting standards.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a research study that aimed to carry out a quantitative and qualitative characterization of food waste from the restaurant sector of Riobamba, Ecuador. The topic of the manuscript corresponds to the aims and scope of the journal. However, for a manuscript to be suitable for publication, revision is required.

 

Given that characterization can be quantitative and qualitative, the title of the article should be modified. I suggest that the revised title be:

Quantitative and Qualitative Characterization of Food Waste for Circular Economy Strategies in the Restaurant Sector of Riobamba, Ecuador: A Case Study Approach

 

Line 19: It is stated that each restaurant generated 18.48 kg of waste per day. How is it possible for the amount of waste generated to be identical? Correct this in the revised manuscript.

 

Please avoid to use abbreviations. If it is necessary abbreviations should be introduced after the first appearance in the text. The abbreviation for waste has been explained more than once. Correct this in the revised manuscript.

 

Is there any data available on the amount of waste generated in Ecuador? If there are any, add them to the section 1. Introduction.

 

Add the aim of the study at the end of the section 1. Introduction.

 

Why are recyclable waste and disposable waste not sub-classified? What belongs to these waste categories?

 

Into which category were bread, dough, and other flour-based food products classified?

 

Add the models and manufacturers of all instruments and their parts used in the research.

 

Please check and correct all formulas in the section 2.2.3. Characterization. Units for all parameters must be specified.

 

In the text of the article, it is necessary to provide the ranges in which the amount of generated waste (section 3.1. Quantitative Generation Data) and the values of the analyzed parameters varied (section 3.2. Characterization Data).

 

Section 3.1. Characterization Data should be renamed to 3.2. Quantitative Characterization Data.

 

Section 3.2. Characterization Data should be renamed to 3.2. Qualitative Characterization Data.

 

To conduct reliable conclusions about the quantity and composition of waste, a long-term analysis is needed. One week is not enough.

 

It is necessary to perform a statistical analysis of quantitative and qualitative characterization data.

 

 

Announce each table and figure before they appear in the text pointing to the data that will be presented.

 

The results given in all tables should be presented as mean values ± standard deviations with statistical significance levels indicated.

 

Check the y-axis titles on the graphs in Figure 1 (the pH value unit is missing). In addition, the scaling of both axes must be uniform across all graphs.

 

Author Response

Comments 1: Given that characterization can be quantitative and qualitative, the title of the article should be modified. I suggest that the revised title be:

Response 1: We thank the reviewer for their suggestion regarding the title of the manuscript. We agree that explicitly specifying both quantitative and qualitative characterization and better reflects the scope and methodology of our study.

Quantitative and Qualitative Characterization of Food Waste for Circular Economy Strategies in the Restaurant Sector of Riobamba, Ecuador: A Case Study Approach

Comments 2: Line 19: It is stated that each restaurant generated 18.48 kg of waste per day. How is it possible for waste generated to be identical? Correct this in the revised manuscript.

Response 2: We appreciate the reviewer’s observation regarding the ambiguity in the original statement. To clarify, the value of 18.48 kg represents the average daily food waste generated per restaurant, calculated across the 13 participating establishments. Individual restaurants contributed varying amounts of waste depending on factors such as size, type of cuisine, and customer traffic. We have revised the manuscript to reflect this clarification and provide additional context to ensure the data is accurately interpreted. Thank you for pointing this out.

Comments 3: Please avoid using abbreviations. If it is necessary abbreviations should be introduced after the first appearance in the text. The abbreviation for waste has been explained more than once. Correct this in the revised manuscript.

Response 3: We have carefully reviewed the manuscript and ensured that all abbreviations are introduced only once, immediately after their first appearance in the text 

Comments 4: Is there any data available on the amount of waste generated in Ecuador? If there are any, add them to the section 1. Introduction.

Response 4: Data avaible for waste generation in Ecuador and Riobamba has been added in the introduction

 

Comments 5: Add the aim of the study at the end of the section 1. Introduction.

Response 5: Aim has been added in the introduction.

Comments 6: Why are recyclable waste and disposable waste not sub-classified? What belongs to these waste categories?

Response 6: We thank the reviewer for their feedback regarding the classification of recyclable and disposable waste. To clarify, we did indeed perform a sub-classification for recyclable waste in our study. Recyclable waste was divided into four main categories: plastics, glass, aluminum, and cardboard, as now explicitly detailed in the revised manuscript.

Comments 7: Into which category were bread, dough, and other flour-based food products classified?

Response 7: In our study, bread, dough, and other flour-based food products were classified under the "vegetable protein" category. This decision assumed that the primary flours used in these products were derived from plant-based sources such as quinoa, barley, and wheat, which are commonly consumed in the Riobamba region. These flours contain significant amounts of vegetable protein, making this classification appropriate within the context of our analysis.

To clarify any potential confusion, it is important to note that bread is not typically consumed during meals at restaurants in Riobamba. Instead, flour-based products in this region are more commonly used to prepare dishes such as soups, stews, and other traditional recipes. As a result, most of the flour-based food waste generated in restaurants stems from these types of preparations rather than from bread or similar items.

It has been updated in the methods section

Comments 8: Add the models and manufacturers of all instruments and their parts used in the research.

Response 8: In response, we have added the details of the manufacturers for all instruments in the Methods section

Comments 9: Please check and correct all formulas in the section 2.2.3. Characterization. Units for all parameters must be specified.

Response 9: We have thoroughly reviewed and corrected all formulas in this section, ensuring that units for all parameters are now clearly specified.

Comments 10: In the text of the article, it is necessary to provide the ranges in which the amount of generated waste (section 3.1. Quantitative Generation Data) and the values of the analyzed parameters varied (section 3.2. Characterization Data).

Response 10: We thank the reviewer for this important observation. The ranges for the amount of generated waste and the analyzed parameters have already been addressed in the revised manuscript

Comments 11: Section 3.1. Characterization Data should be renamed to 3.2. Quantitative Characterization Data.

Response 11: The suggested change has been incorporated into the manuscript 

Comments 12: Section 3.2. Characterization Data should be renamed to 3.2. Qualitative Characterization Data.

Response 12: The suggested change has been incorporated into the manuscript

Comments 13: To conduct reliable conclusions about the quantity and composition of waste, a long-term analysis is needed. One week is not enough.

Response 13: We thank the reviewer for their valuable comment regarding the duration of the analysis. While we agree that long-term studies provide more comprehensive insights into waste generation patterns, the one-week (7-day) analysis in this study aligns with widely accepted methodologies and practices in food waste characterization, particularly in restaurant and municipal solid waste studies.

Our methodology is based on established guidelines and previous studies, including:

• The Standard Test Method for Determination of the Composition of Unprocessed Municipal Solid Waste (ASTM D5231-92, Reapproved 2016) , which explicitly recommends conducting sampling over a 5–7-day period to capture variability in waste generation. Additionally, the method specifies that the number of samples should be defined based on statistical criteria (ASTMD5231-92 (Reapproved 2016)).
• The FAO Guidelines for the Characterization of Urban Solid Waste , which also recommend a 7-day sampling period to ensure representative data (FAO 2019).

Previous studies on food waste in the restaurant sector, such as those by Carmona-Cabello et al. (2020) and Hidalgo Crespo et al. (2022) , both of which used a 7-day sampling period to analyze waste generation patterns. Similarly, Abd Alqader and Hamad (2012) conducted a 7-day analysis for municipal solid waste characterization, further supporting the validity of this timeframe The choice of a 7-day period in our study was also guided by practical considerations, such as resource constraints and the availability of participating restaurants. Importantly, the selected week included both weekdays and weekends to account for variations in customer traffic and restaurant operations. This approach ensures that the data collected is representative of typical operational conditions in the restaurant sector.

• ABD ALQADER, A. & HAMAD, J. 2012. Municipal solid waste composition determination supporting the integrated solid waste management in Gaza strip. International Journal of Environmental Science and Development, 3, 172.
• ASTMD5231-92 (Reapproved 2016). Standard Test Method for Determination of the Composition of Unprocessed Municipal Solid Waste.
• CARMONA-CABELLO, M., GARCíA, I., SáEZ-BASTANTE, J., PINZI, S., KOUTINAS, A. & DORADO, M. 2020. Food waste from restaurant sector–Characterization for biorefinery approach. Bioresource technology, 301, 122779.
• HIDALGO CRESPO, J. A., SOTO, M., AMAYA-RIVAS, J. L., BORJA-MORA, L., ROBLES-IGLESIAS, R. & BANGUERA ARROYO, L. A. Towards a Circular Economy for Restaurant Waste in Guayaquil: Characterization and Energy Generation Potential. International Conference on Energy and Environment Research, 2022. Springer, 537-545.
• FAO (2019). "Background: technical platform on the measurement and reduction of food loss and waste." 2024, from https://www.fao.org/platform-food-loss-waste/en/.

 

Comments 14: It is necessary to perform a statistical analysis of quantitative and qualitative characterization data.

Response 14: We thank the reviewer for this recommendation. In response, we have included relevant statistical analyses where necessary to strengthen the presentation of our findings. Specifically:

For recyclable waste, we did stadistical analysis for each subcategory (e.g., plastics, glass, aluminum, and cardboard).

For waste weight data, we calculated the mean and SD to provide a clearer understanding of variability in waste generation.

Comments 15: Announce each table and figure before they appear in the text pointing to the data that will be presented.

Response 15: We have addressed this recommendation by ensuring that each table and figure is announced in the text

Comments 16: The results given in all tables should be presented as mean values ± standard deviations with statistical significance levels indicated

Response 16: we have update the applicable tables

Comments 17: Check the y-axis titles on the graphs in Figure 1 (the pH value unit is missing). In addition, the scaling of both axes must be uniform across all graphs.

Response 17: We understand the reviewer’s suggestion to maintain uniform scaling of both axes. However, due to the significant variation in values across different food waste types (e.g., Ash % and pH), uniform scaling would obscure the trends and reduce interpretability.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have discussed the most important issue of food wastes and recovery of them within the circular economy framework. The manuscript reads well and can be considered as a preliminary benchmark for quantifying the food wastes that might land up in the compost. Some of the comments from my side regarding the manuscript:

1. Although the authors have mentioned a bit about the infrastructure in Riobamba regarding the waste valorization in conclusion, it would be advisable to discuss the policy framework and facilities in there, that will collect, valorize and compost the food wastes (in Introduction) apart from the methods mentioned in here.
2. Please change Figure 2 to color as it is not clear with Black and White

Author Response

Comments 1: Although the authors have mentioned a bit about the infrastructure in Riobamba regarding the waste valorization in conclusion, it would be advisable to discuss the policy framework and facilities in there, that will collect, valorize and compost the food wastes (in Introduction) apart from the methods mentioned in here.

Response 1: We thank the reviewer for this suggestion. In response, we have expanded the Introduction section to include a discussion of the policy framework and infrastructure in Riobamba related to waste valorization and composting. Specifically, we have highlighted the role of the Ordenanza Municipal de Gestión Integral de Residuos Sólidos, which mandates source separation programs and collaboration with municipal waste management services. Additionally, we have referenced the national Circular Economy Law (2021), which provides a framework for minimizing waste generation, encouraging recycling, and fostering sustainable practices.

 

Comments 2: Please change Figure 2 to color as it is not clear with Black and White

Response 2: In response, we have updated the figure by incorporating color coding for all graphs

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have improved the manuscript through comprehensive revision. All the suggestions and comments provided in the first round of revision have been addressed. Therefore, I am in favor of acceptance of this manuscript for publication in its current form.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a research study that aimed to carry out a quantitative and qualitative characterization of food waste from the restaurant sector of Riobamba, Ecuador. The authors adequately answered all comments in their response letter, and the quality of the manuscript has significantly improved.