Influence of glycerol, eggshells, and genipin on hydrophobicity and rigidity of antioxidant locust bean milling dust-derived bioplastics.

Locust bean milling dust (LBMD) is an agrifood byproduct rich in proteins and polysaccharides able to form hydrophilic, flexible, and antioxidant bioplastics. Aiming a broad application for LBMD-based bioplastics, in this work, it was hypothesized that glycerol, milled eggshells, or genipin amount fine-tuning can originate rigid and hydrophobic antioxidant LBMD-based materials. With 20 g/100 g glycerol, the films became more 10-fold stiff (Young's modulus of 253 MPa), 1.7-fold hydrophobic (water contact angle of 109°), and 22-fold resistant to water vapor (5 pg/Pa.s.m) than pristine films (Young's modulus of 26 MPa, water contact angle of 64°, and water vapor permeability of 109 pg/Pa.s.m), keeping their yellowish color and transparency. Apart from stiffness that did not change, this profile was also evidenced when 1 g/100 g milled eggshells were incorporated, increasing hydrophobicity 1.5 times and decreasing water vapor permeability 1.6 times. The use of 0.03 g/100 g genipin conferred a blue color to LBMD-based bioplastics and more 5-fold rigidity, 1.7-fold hydrophobicity, and 2.2-fold water vapor barrier. Therefore, rigid, water tolerant, and antioxidant LBMD-based bioplastics can be developed by tailoring glycerol, milled eggshells, or genipin amount, with 20 g/100 g glycerol or 0.03 g/100 g genipin as best conditions to improve these features. [Display omitted] • Locust bean milling dust (LBMD) gives rise to flexible and antioxidant bioplastics. • 20 g/100 g glycerol originates the most hydrophobic and stiff LBMD-based films. • Eggshells increase the water tolerance of LBMD-based films. • LBMD protein-genipin networks increase the films hydrophobicity and stiffness. • LBMD blended with glycerol, eggshells, or genipin originates antioxidant bioplastics [ABSTRACT FROM AUTHOR]