Upgrading agrifood co-products via solid fermentation yields environmental benefits under specific conditions only

Waste-to-nutrition pathways are explored with process-based life cycle assessments of four valorization pathways for a panel of representative agrifood co-product streams. Although the principles of circular bioeconomy represent important guidelines for overall sustainability, they are not enough to support decisions for resource allocation. Transforming residual biomass into edible ingredients is increasingly promoted to alleviate the environmental impacts of food systems. Yet, these approaches mostly rely on emerging technologies and constrained resources, and their environmental benefits remain unclear. By combining process-based consequential life cycle analysis, uncertainty assessment and biomass resource estimation, we quantified the impacts of deploying waste-to-nutrition pathways, here applied to the upgrading of agrifood co-products by solid-state fermentation (SSF). The benefits of reducing the demand for soybean meal by enhancing the protein concentration of feed through SSF do not compensate for the environmental burdens induced by the process on climate change, water depletion and land use. Besides unlocking feed markets to low-feed-quality streams, SSF outperforms energy valorization for most environmental impacts but is less competitive to mitigate climate change. Yet, SSF yields overall environmental benefits when unlocking food markets rather than supplying feed and energy services. Systematic methodological harmonization is required to assess the potential of novel ingredients, as outcomes vary according to the displaced food and feed baskets, and related land use changes.

Automated summary

This study explores various methods of transforming agrifood co-products into nutritious substances and assesses the environmental impacts of these waste-to-nutrition pathways. The results show that solid-state fermentation has the potential to reduce the demand for soybean meal, but its environmental burdens on climate change, water depletion, and land use are not significantly alleviated.