From Food Processing Leftovers to Bioplastic: A Design of Experiments Approach in a Circular Economy Perspective

Aiming at reducing the environmental impact of low density polyethylene (LDPE) when employed as mulching film, this study was focused on the partial substitution of the material with proteins extracted from Hermetia illucens, also known as black soldier fly (BSF). Insects were reared on chicken manure and food leftovers in a circular economy perspective. To evaluate the effects of processing conditions and amount of BSF proteins on the properties of the final material the Design of Experiments technique was employed. Samples were obtained by hot mixing and compression molding, and their thickness, tensile stress, tensile strain, and Young modulus were measured and analyzed. According to mathematical models, the addition of BSF proteins in the mixture results in increased homogeneity and Young modulus of the material and in reduced tensile stress and strain. Results indicated that a LDPE-BSF proteins mixture of 50–50 wt%, processed at relative low temperature (130 °C) and time (3 min), ensures properties closer to pure molded LDPE (thickness = 0.8 mm, tensile stress = 6 MPa, tensile strain = 15% and Young modulus = 200 MPa) with lower environmental impact thanks to the high BSF proteins addition. Thereafter, BSF proteins can be employed as additive for LDPE for agricultural purposes, with processing methods feasible in an industrial perspective.