Bioplastics from renewable waste: Safe and edible wrapping materials for farm animal feeds

Wrapping materials used for farm animal feeds (e.g., bales) are mostly polyethylene-based plastics which are required to be removed from the bales before feeding the farm animals. Feeding cattle without removing the plastic binding on the bales (grinding bales with wrap) causes serious problems on animal health. In the present study, the bioplastics were developed from low-grade woody biomass and low-value/non-edible proteins (poultry feathers keratin) as main ingredients. The bioplastic formulations were also composed of starch and glycerol in low quantities. The mixture containing biomass/feather ratio of 5/0.9 (w/w) and starch/glycerol ratio of 3.75/1 (w/w) resulted in a good bioplastic. Addition of PVA to the formulation in a small quantity (PVA/starch: 1/20, w/w) improved physical properties of the bioplastics (smoother and more even surface) while decreasing the carbohydrate content (starch or biomass) of the formulations resulted in fragile films. The bioplastics developed were susceptible to degradation in open environmental conditions as having high water absorption (95 %) and high transparency (1.74) values. Thermogravimetric analysis (TGA) showed that the bioplastics developed were thermally stable until 75 °C and not decomposed until 200 °C. These bioplastics also showed high digestibility in the rumen microbes (>95 %) indicating they are edible and digestible for farm animals. One of the promising bioplastics withstood one year in a barn-like wooden room without considerable changes in its structure and with no degradation. However, this bioplastic completely degraded in 4 months in open environmental conditions.