Food loss and waste (FLW) is a significant global issue impacting food security and the environment. Developing economies, particularly China, experience alarming increases in FLW, contradicting efforts to feed a large population with limited resources. The UN's Sustainable Development Goal 2.0 (Zero Hunger) and Target 12.3 aim for a 50% reduction in FLW by 2030. Existing research on FLW in China is limited by its scope, data quality, and sample size. Most studies lack comprehensive supply chain analysis across various food categories. This study addresses these gaps by employing MFA to comprehensively assess food waste across the entire food supply chain in China for seven major food categories. The study aims to identify key waste points, quantify waste amounts, and assess the potential impact of waste reduction on reducing reliance on imported soybeans. The FAO's definition of FLW is adopted, differentiating between food loss (unintentional reduction) and food waste (intentional discarding).

Previous research on food waste in China has employed various methodologies, including bookkeeping approaches, archeological methods, weighing plate leftovers, and inferences from secondary data. Each method has limitations. Bookkeeping relies on respondent recall, prone to bias; archeological approaches miss food disposed of improperly; weighing plate leftovers are time-consuming and have limited sample sizes; and inferences from secondary data suffer from data availability and accuracy issues. While some studies have focused on specific food chains (e.g., pork, rice, apples), comprehensive analyses across multiple food categories and stages of the supply chain are lacking, particularly for vegetables, aquatic products, and milk. The study highlights the limited application of MFA in food waste research, despite its potential for comprehensive analysis and identification of patterns in material flows. Previous studies have applied MFA in other contexts (e.g., energy flow in the food supply chain, environmental impacts of food waste).

This study utilizes material flow analysis (MFA) to quantify food waste in China from 2010 to 2019. The spatial boundary encompasses the entire country, including mainland China, Hong Kong, Macau, and Taiwan. The temporal scope covers the ten-year period. The system boundary includes the entire food supply chain, from agricultural production to consumption, considering imports and exports. Seven food categories were selected (wheat, soybeans, apples, tomatoes, pork, freshwater fish, and milk) based on their consumption significance in China and FAO classification. Data primarily come from the FAO's Food Balance Sheets, supplemented by other sources. The MFA approach follows the principle of mass conservation, tracking the flows of materials through each stage of the supply chain and calculating waste rates. The analysis is based on a series of equations that model the flow of food through production, post-harvest handling and storage, processing and packaging, distribution, and consumption, taking into account imports, exports, feed, seed, and other non-food uses. STAN 2.5 software was utilized for the analysis. The study clearly defines terms such as production, stock variation, processing, and consumption to ensure consistency and accuracy in data interpretation.

The analysis reveals wheat as the most wasted food category (45.7 Mt, 38% of total waste), followed by tomatoes, apples, pork, freshwater fish, soybeans, and milk. Wheat waste was highest in post-harvest handling and storage, processing and packaging, and consumption stages. Tomatoes had the highest waste in production and distribution. By stage, the highest average annual waste was observed in the consumption stage, followed by processing and packaging, post-harvest handling and storage, production, and distribution. Examining waste by category shows that wheat, apples, tomatoes, pork, and milk exhibited the highest waste at the consumption stage; soybeans had the highest waste during processing and packaging; and freshwater fish during production. Soybeans had the lowest utilization rate (67%), primarily due to high import reliance. A scenario analysis, assuming a 5% reduction in waste across all five stages, projected a 7% decrease in soybean imports. This underscores the potential of waste reduction strategies in improving food security and reducing import dependence.

The study's findings highlight the significant amount of food waste generated at various stages of the food supply chain in China. The high levels of waste in the consumption stage, particularly for wheat, apples, tomatoes, pork, and milk, emphasize the need for interventions targeting consumer behavior. The considerable waste of soybeans at the processing and packaging stage points towards inefficiencies within the processing industry. The substantial waste of freshwater fish at the production stage indicates a need for improvement in fishing practices and technology. The strong correlation between waste reduction and reduced soybean import dependency reveals the economic and strategic benefits of implementing effective food waste management programs. The analysis contributes significantly to the understanding of food waste patterns in China and supports the development of targeted interventions.

This study provides a comprehensive assessment of food waste in China using MFA, revealing key waste points across different food categories and stages of the supply chain. The findings underscore the importance of targeted interventions to reduce food waste, emphasizing the need for policies focusing on consumer behavior, improvements in processing and handling, and optimized supply chains. The potential for significant reductions in soybean imports through waste reduction strategies is a critical finding with both economic and environmental implications. Future research could focus on refining the methodology, expanding the scope of food categories, and developing more detailed scenario analyses to guide policy development and implementation.

The study relies on data from secondary sources, particularly the FAO's Food Balance Sheets, which may have inherent limitations in accuracy and completeness. The selection of seven food categories may not fully represent the diversity of food items consumed in China. The scenario analysis is based on assumptions about waste reduction potential, and actual reductions may vary depending on policy effectiveness and other factors. The study focuses on quantitative assessment of food waste and does not extensively explore the socio-economic drivers behind these patterns.