Assessment of the performance of several novel approaches to improve physical properties of guar gum based biopolymer films

• Orange peel oil/HNT addition or crosslinking improved physical properties of films. • Samples studied had distinctly different solubilities and visual appearances. • Orange peel oil and HNT addition increased film hydrophobicity. • All films other than control displayed antimicrobial activity. Biopolymer-based films are natural, renewable, nontoxic and biodegradable alternatives to plastic packaging. Despite years of ongoing research, biopolymer films still lag much behind plastic films in mechanical and barrier properties. In this study, guar gum (GG) based films were prepared to evaluate the potential of some novel applications in enhancing films physical properties. For this purpose, GG and glycerol based films were prepared with varying amounts of orange peel oil (1%, 2% v/v), and/or reinforced with halloysite nanotubes (HNT), and crosslinked with sodium trimetaphosphate (STMP). Oil incorporation, despite weakening films’ mechanical strength, increased film hydrophobicity and enhanced its water barrier properties. Crosslinking, decreased films’ relatively high solubility while also improving other film properties. Orange peel oil preserved its antimicrobial activity and HNT stabilized GG films provided controlled release of volatile essential oil. Findings indicated the possibility of improving physical properties of GG films with the methods employed.