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.

Edible films are manufactured from natural, renewable, nontoxic, and biodegradable polymers and are safe alternatives to plastic food packaging. Despite ongoing research, biopolymer-based edible films still are not at a quality to ensure total commercial replacement of synthetic packaging materials. The study aims to compare the effectiveness of some novel methods employed to improve edible film properties. These include dispersion of orange oil (1% & 2% v/v) and/or curcumin into guar gum (GG), glycerol and lecithin-based edible films that are further reinforced with Sodium trimetaphosphate (STMP) crosslinking with the aim enhancing films physical properties. The films were characterized by measurement of film thickness, density, moisture content, water dissolvability, FTIR Spectroscopy, opacity, water vapor permeability, tensile properties, and antimicrobial activity. Orange oil and curcumin preserved their antimicrobial activity inside the films, which bestowed the films with an active packaging function. Control GG films had acceptable tensile and barrier properties that were further improved. All other film properties, such as opacity, dissolvability, and moisture content, that should be designed for specific application, were successfully modified with the methods used. Our results confirm successful application of STMP crosslinking, emulsion film formation, and active agent addition to edible films in manufacturing GG films for packaging.

Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J-spectra. We develop a computational approach that allows quantitative calculation of J-spectra in the presence of chemical exchange and apply it to study aqueous solutions of [¹⁵N]ammonium (¹⁵N[Formula: see text]) as a model system. We show that pH-dependent chemical exchange substantially affects the J-spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2-¹³C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement.