Innovative development of injection-molded biodegradable zein blends with xanthan gum

In this work, environmentally friendly materials based on zein, glycerol, and xanthan gum (XG) are developed through the innovative use of extrusion and injection-molding methodologies for this type of bioplastic materials. This methodology has never been applied to thermoplastic zein materials and this approach represents a significant advancement over traditional cast film methods, enabling enhanced control over properties and expanding potential applications thanks to the possibility of producing new geometries. Mechanical properties show that XG increases the stiffness and hardness of the materials, achieving elastic modulus of 1294 MPa and tensile strengths of 21 MPa. The thermal stability of the formulations is also enhanced by the addition of XG, which considerably increases the maximum degradation rate temperature from 259 up to 340ºC. The wettability of the materials is assessed by contact angle measurements, which show a very high hydrophilicity (29º), nonetheless, it was decreased to not so extremely low contact angle values thanks to the addition of XG (50º), which is very positive from the point of view of food packaging applications. Finally, all materials proved to be completely disintegrated under controlled compost conditions after 9 weeks of incubation in controlled compost soil conditions, verifying the great environmentally friendly value of these formulations. • Zein-glycerol-xanthan gum materials were developed through injection-molding. • Xanthan gum increases stiffness and hardness of zein thermoplastic materials. • Xanthan gum and zein have certain miscibility. • Xanthan gum increases the thermal stability of thermoplastic zein materials.