Redefining the future of catering waste application in animal diets - A review on the minimization of potential hazards in catering waste prior to application in animal diets

Food waste (FW) reutilization as animal feed can alleviate both the burden posed by FW disposal as well as that of food insecurity. Studies on the incorporation of catering waste (CW) in swine and poultry diets have provided promising results in regard to animal performance and quality of derived products. However, disease concerns have led to the prohibition of the above-mentioned practice in the European Union (EU). It is necessary that biological, chemical and physical hazards in CW are examined and controlled. The risk of biological hazards such as exotic viruses posed by feeding CW to animals can primarily be reduced by processing of CW prior to feeding, preventing cross-contamination between raw and processed CW, and separating animal materials in CW based on animal species, as they are considered important risk factors. For the minimization of biological hazards in CW, hydrothermal treatment, extrusion, heat treatment, fermentation and solar drying resulted in considerably reduced concentrations of hygiene indicators in the studies examined, while pathogenic microorganisms were not detected in most cases. Chemical hazards in CW include but are not limited to heavy metals the concentrations of which can be controlled at low levels through risk analysis and sampling. Physical hazards in CW including, but not limited to, paper, metal and plastic are separated manually and/or mechanically. Spoilage of CW has been little studied and one study suggests that community structures in CW which is composed of the same food constituents vary when it is collected from different locations. Furthermore, biogenic amines are associated with spoilage and may affect animal health and performance. Lipid peroxidation is another issue that should be limited through measures such as adding antioxidants in the diet and lowering exposure of CW to heat during thermal processing. Salt content of CW is elevated and this should be taken into account during feed formulation. Processing of FW is essential to substantially decrease the risk of animal diseases transmission.