Formation of phenolic compound-loaded zein films at the air-liquid interface and their controlled release profiles: Effects of the polarity of phenolic compounds.

Polyphenols are frequently utilized antioxidants in active packaging and anti-immflamotary bioactives in tissue engineering. Herein, we introduced a novel method for the rapid (<5 s) fabrication of interfacial self-assembled zein films (ZF) at the air-water interface. Polyphenols with different partition coeffient (Log P), namely, curcumin, resveratrol, and quercetin, were simultaneously loaded during the laterally occurred self-assembly process of zein molecules, respectively. Efficient loading and smart regulation over the physical distribution, intramolecule interaction and release profile in ZF were achieved. The main zein-polyphenol interactions exhibited hydrogen bonding and hydrophobic interactions that modulated the surface micromorphology of ZF and the release kinetics of different polyphenols. The log P of polyphenols affected the strength of the interaction of zein molecules, which in turn influenced the sustained release properties of polyphenols. This "bottom-up" strategy offers a novel way to rapidly incorporate and delicate control over the release of polyphenols.

Hierarchically Porous Films Architectured by Self-Assembly of Prolamins at the Air-Liquid Interface.

Artificial recapitulation of hierarchically porous films gained great interest due to their versatile functionalities and applications. However, the development of novel eco-friendly and nontoxic biopolymer-based porous films is still limited by the time-consuming fabrication processes and toxic organic reagents involved. Here, we reported a novel approach to rapidly (within 5 s) fabricate biopolymer-based hierarchically porous films via inducing the laterally occurring interfacial self-assembly of prolamins at the air-liquid interface during an antisolvent dripping procedure. The as-prepared films exhibited a hierarchically porous microstructure (with sizes of about 500 nm to 5 µm) with location-graded and Janus features. The formation mechanism involved the solvent gradient controlled self-assembly of prolamin into an anisotropic defect structure in longitudinal and lateral directions. Accordingly, the macroscopic morphologies together with the porosity and pore size could be precisely tuned by solvents and operating parameters in a convenient way. Furthermore, alcohol-soluble but water-insoluble bioactive compounds could be incorporated simultaneously via a one-step loading procedure, which endowed films with large loading efficiency and sustained release features suitable for controlled release applications. The effect of the curcumin-loaded porous film on skin wound healing, as one of the potential applications of this novel material, was then investigated in vivo in a full-thickness wound model, wherein satisfying wound healing effects were achieved through multitarget and multipathway mechanisms. This pioneering work offers a novel strategy for the rapid architecture of biopolymer-based hierarchically porous film with versatile application potentials.

Volatile composition changes of fruits in a biopolymer-coated polyethylene active packaging: Effects of modified atmosphere and packaging-shaped bacterial community.

The potential impacts of active packaging on the volatile composition of fruits during preservations largely associated with consumers' acceptance, yet was barely investigated. In this work, a biopolymer-coated polyethylene active film was developed and its effects on qualities and volatile compositions of fruits with different respiration rates were comprehensively investigated. Underlying reasons for the effect of active packaging on volatile composition change of fruits were elucidated through revealing ternary relationship among the packaging-shaped bacterial community, modified atmosphere and volatiles. Off-flavor production was reduced and more sesquiterpenes (α-cubebene, copaene, ß-caryophyllene, α-caryophyllene, d-amorphene) were reserved for longan packaged with active film, due to its antimicrobial and moisture absorption ability, as leading contributors to the selective inhibition on spoilage bacteria genera including Zymobacter, Gluconobacter and Pantoea. Whereas volatile profile of strawberry with high respiration rate was more actively affected by the modified atmosphere induced by packaging, instead of the bacterial community, where hypoxia (<2% O2) led to the accumulation of ethyl esters (0.154-0.184 µg/g) that conferred off-flavor but decreased production of methyl (0.172-0.367 µg/g) and hexyl esters (1.26-1.89 × 10-2 µg/g) that represented typical fruity aroma. This work adds new knowledges on impacts of active packaging on the volatile profile of fruits and would provide guidance to smart design of active packaging for preservation of aromatic fruits.