Valorisation of agri-food waste and mealworms rearing residues for improving the sustainability of Tenebrio molitor industrial production

The challenge of feeding over 9 billion humans by 2050 requires a ‘rethink’ of the current linear food production system. In the view of a circular economy, insects can provide a possible solution to valorise waste to produce new foods and materials, as well as the opportunity to solve some environmental problems. Tenebrio molitor (TM) is the first insect approved by the European Commission as a novel food and widely explored by the research world. Although mass production of TM is still not competitive compared to traditional protein sources, studies and companies in the sector are improving the entire production process to meet the growing need for alternative and sustainable protein foods. The use of food loss and waste to replace commercial feed in TM rearing can improve the economic and environmental sustainability of the production process. Furthermore, the exploitation of the variety of TM-based products can lead to the creation of new value chains and employment opportunities. In this review, we focus on the ability of TM to convert low-value substrates into novel foods and materials, as well as the possibility of using the TM rearing waste to obtain fertilisers and bioproducts, such as chitin and chitosan. TM capacity to degrade plastic waste such as polyethylene and polystyrene, thanks to its highly differentiated gut microbiota, is mentioned. Critical aspects related to sustainability and scaling-up of TM rearing are analysed. Hints on food safety of TM-based products are provided. Therefore, this study is a comprehensive review of TM multifunctionality and, at the same time, identifies possible ways to improve the economic and environmental impact of this insect with a circular economy perspective.