Bioconversion of fruit and vegetable waste into earthworms as a new protein source : the environmental impact of earthworm meal production

Food waste is recognized as a global issue affecting the sustainability of the food supply chain. The unnecessary exploitation of natural resources (land, water and fossil energy)and production of greenhouse gas emissions (GHG)make the reduction of food waste a key point. In this context, the use of fruit and vegetable waste (FVW)as growth substrate for fresh earthworms to produce dried meal for feed and food purpose can be recognized as a viable solution. Therefore, the aim of this study is to evaluate the environmental impact of the bioconversion of FVW into earthworm meal to be used as new food/feed source. This is carried out by adopting the Life Cycle Assessment (LCA)method with an attributional approach and solving the multifunctionality of the system with an economic allocation between earthworms and vermicompost. The results show that the main process hotspots are the emissions of methane, dinitrogen monoxide and ammonia taking place during vermicomposting, as well as FVW transport and electricity consumed during fresh earthworm processing. Respect to the one used as feed, the dried meal with food purpose shows a higher impact due to the higher economic value and to the higher electricity consumed during freeze drying compared to the oven-drying process for feed meal production. Enhancing productivity and reducing energy consumption are necessary to improve the sustainability of earthworm meal as food/feed source.