Material Flow Analysis of Innovative Utilization Pathways of Bread Waste in Austria: Comparing Economic, Ecological and Social Criteria

Abstract

Bread ranks among the most discarded food items globally, contributing to approximately 30% of all food waste in Europe. In Austria alone, bread waste totaled 161,900 tons in 2024, with nearly 60% originating from households, followed by 32% from production and 8% from the retail sector. While public awareness and educational campaigns primarily target household-level waste reduction, this study shifts focus on evaluating innovative valorization strategies for the approximately 65,000 tons of surplus bread generated by the retail and production sectors. Specifically, it investigates the potential of converting bread waste into beer, animal feed, or bioethanol.A material flow analysis (MFA) was conducted, supported by Sankey diagrams to illustrate both current and alternative waste pathways within the Austrian food system. To address data uncertainty, an uncertainty and error propagation analysis was applied, quantifying standard deviations for each scenario. The findings reveal that existing utilization routes result in estimated greenhouse gas savings of 32,600 ± 5,400 tons CO2-equivalents compared to scenarios in which no repurposing occurs. Among the three valorization options, bioethanol production demonstrates the highest potential for environmental benefit, with estimated emission savings of 36,000 ± 3,370 tons CO2-eq. In contrast, the production of beer and animal feed yields comparatively lower reductions of 29,900 ± 2,801 and 34,500 ± 3,230 tons CO2-eq, respectively.The study further evaluates these three pathways against the current fragmented approach, using a multi-criteria analysis incorporating environmental, social, and economic dimensions. Overall, the results highlight the substantial climate mitigation potential of bread waste valorization, with bioethanol production offering the most significant environmental advantage.