Pickering nanoemulsion loaded with eugenol contributed to the improvement of konjac glucomannan film performance.

Konjac glucomannan (KGM) is becoming a very potential food packaging material due to its good film-forming properties and stability. However, KGM film has several shortcomings such as low mechanical strength, strong water absorption, and poor self-antibacterial performance, which limits its application. Therefore, in order to enhance the mechanical and functional properties of KGM film, this study prepared Pickering nanoemulsion loaded with eugenol and added it to the KGM matrix to explore the improvement effect of Pickering nanoemulsion on KGM film properties. Compared to pure KGM film and eugenol directly added film, the mechanical strength of Pickering-KGM film was significantly improved due to the establishment of ample hydrogen bonding interactions between the ß-cyclodextrin inclusion complex system and KGM. Pickering-KGM film had significant antioxidant capacity than pure KGM film and eugenol directly added KGM film (eugenol-KGM film) (~3.21 times better than KGM film, ~0.51 times better than eugenol-KGM film). In terms of antibacterial activity, Pickering-KGM film had good inhibitory effect on Escherichia coli, Staphylococcus aureus, and Candida albicans, and raspberry preservation experiment showed that the shelf life of the Pickering-KGM film could be extended to about 6 days. To sum up, this study developed a novel means to improve the film performance and provide a new insight for the development and application of food packaging film.

Inhibitory effects of nobiletin-mediated interfacial instability of bile salt emulsified oil droplets on lipid digestion.

Previous lipase inhibitors studies mainly focus on the binding between inhibitors and lipase, ignoring the impact of inhibitors on the oil-water interface of lipid droplets. This study aimed to investigate the effect of nobiletin (NBT) from Citri Reticulatae Pericarpium on the oil-water interface properties and lipid digestion. Here, we found that NBT could destroy bile salt (BS)-stabilized lipid droplets and thus inhibited free fatty acid release, owing to the interaction between NBT and BS at the oil-water interface, and reducing the stability of the oil-water interface (the stability index decreased from 91.15 ± 2.6 % to 66.5 ± 3.6 %). Further, the molecular dynamics simulation and isothermal titration calorimetry revealed that NBT could combine with BS at oil-water interface through intermolecular interactions, including hydrogen bonds, Van der Waals force, and steric hindrance. These results suggest that the interfacial instability of NBT mediated BS emulsified oil droplets may be another pathway to inhibit lipid digestion.

Antibacterial aroma compounds as property modifiers for electrospun biopolymer nanofibers of proteins and polysaccharides: A review.

Electrospinning is one of the most promising techniques for producing biopolymer nanofibers for various applications. Proteins and polysaccharides, among other biopolymers, are attractive substrates for electrospinning due to their favorable biocompatibility and biodegradability. However, there are still challenges to improve the mechanical properties, water sensitivity and biological activity of biopolymer nanofibers. Therefore, these strategies such as polymer blending, application of cross-linking agents, the addition of nanoparticles and bioactive components, and modification of biopolymer have been developed to enhance the properties of biopolymer nanofibers. Among them, antibacterial aroma compounds (AACs) from essential oils are widely used as bioactive components and property modifiers in various biopolymer nanofibers to enhance the functionality, hydrophobicity, thermal properties, and mechanical properties of nanofibers, which depends on the electrospun strategy of AACs. This review summarizes the recently reported antimicrobial activities and applications of AACs, and compares the effects of four electrospinning strategies for encapsulating AACs on the properties and applications of nanofibers. The authors focus on the correlation of the main characteristics of these biopolymer electrospun nanofibers with the encapsulation strategy of AACs in the nanofibers. Moreover, this review also particularly emphasizes the impact of the characteristics of these nanofibers on their application field of antimicrobial materials.

Cellulose nanocrystals-composited poly (methyl methacrylate) encapsulated n-eicosane via a Pickering emulsion-templating approach for energy storage.

Microencapsulated phase change composite materials (MPCMs) with cellulose nanocrystals-composited poly (methyl methacrylate) (PMMA) as shell and n-eicosane as core was facially prepared via Pickering emulsion assisted solvent evaporation approach. PMMA and n-eicosane were dissolved in chloroform as the oil phase. Cellulose nanocrystals (CNC) can efficiently stabilize oil - in - water (O / W) emulsion, and the core-shell ratio will affect the thermal properties of MPCMs, study found that the optimal core-shell ratio was 1:2 and encapsulation ratio reached 58.2 %. The PMMA encapsulated MPCMs displayed a regular spherical shape sized in the range of 5-10 micrometers. They had favorable thermal stability and melting enthalpy of up to 150.8 J/g. Results of the thermal cycling tests showed melting enthalpy of MPCMs were maintained by over 99 % after 100 heating-cooling cycles. The proposed Pickering emulsion assisted solvent evaporation approach provides a potential way for industrial production of microencapsulated phase change materials.

A naked-eye detection polyvinyl alcohol/cellulose-based pH sensor for intelligent packaging.

Naked-eye detection pH sensor is becoming a powerful tool in food safety monitoring. In this work, a pH sensor was developed by incorporating cellulose modified with acidochromic dye into polyvinyl alcohol (PVA). The results indicated that the dye (up to 170.4 µmol/g) was successfully anchored to cellulose. It was demonstrated that the addition of acidochromic regenerated cellulose (ARC) resulted in enhancement of tensile strength, elongation at break and maximum decomposition temperature by 44 %, 43.6 % and 11 °C, respectively. The pH sensor demonstrated that a visible color change from yellow to brick-red and to purple when placed in solutions of pH = 7, 10 and 12. The pH sensor showed excellent resistance to leaching under strong acidic and alkaline conditions. When applied to spoiled shrimp, an evident color change from yellow to brown was observed, suggesting it could serve as an easy-to-use, non-destructive visual indicator system for real-time food monitoring.

Fabrication of lignin/poly(3-hydroxybutyrate) nanocomposites with enhanced properties via a Pickering emulsion approach.

The present-day world still demands for various commercially viable biosourced materials to replace the finite petroleum-derived polymers. Herein, lignin nanoparticles were homogeneously dispersed in the poly(3-hydroxybutyrate) (PHB) matrix via an economical, simple and environmentally friendly oil-in-water Pickering emulsion approach to form a nanocomposite with improved properties. The prepared lignin/PHB nanocomposites were investigated for their morphological, thermal, optical, rheological and mechanical properties. The lignin nanoparticles proved to be efficient nucleating agents for PHB in that they noticeably increased the crystallization rates of the polymer. PHB film containing 7% lignin demonstrated the optimum improvement in the tensile performance with 13.2% and 43.9% increase in tensile strength and Young's modulus, respectively. This upturn was ascribed to the uniform dispersion of the lignin nanoparticles and the formation of strong interfacial adhesion between the filler and the matrix due to hydrogen bonding interactions. Moreover, lower crystallinity, higher glass transition temperature, improved UV resistance/blocking and higher melt viscosity were achieved in the blends. The synergetic advancement in these properties may be of significant importance for the wider application of bio-sourced PHB in the packaging industry.

The fabrication of polylactide/cellulose nanocomposites with enhanced crystallization and mechanical properties.

Polylactide/cellulose nanocomposites were fabricated by blending of commercial polylactide (PLA) and modified cellulose nanocrystals (CNCs). Modified CNCs were prepared via the in situ polymerization of CNCs and L-lactic acid (CNCs-PLLA) or D-lactic acid (CNCs-PDLA). The actual occurrence of chemical bond between CNCs and PLA segment was confirmed by Fourier transform infrared, nuclear magnetic resonance, X-ray diffraction and solubility tests. Differential scanning calorimetry and X-ray diffraction characterization indicated that CNCs-PDLA better improved the crystallization ability of PLA matrix compared with CNCs-PLLA. Furthermore, compared with the neat PLA (60.0 MPa), the tensile strength of resulting nanocomposites showed an enhancement of up to 36% (81.65 MPa). And the nanocomposites with CNCs-PDLA exhibited both high crystallinity and improved mechanical properties.

Regenerated cellulose-dispersed polystyrene composites enabled via Pickering emulsion polymerization.

Cellulose composites are an important class of polymeric composites due to their renewable, biodegradable feedstock, and tend to have exceptional properties due to peculiar increase of the matrix-filler interface. In this work, a new breed of colloids enabled by regenerated cellulose (RC) was used to prepare polystyrene/cellulose composites. Specifically, an oil-in-water Pickering emulsion of styrene stabilized by RC was prepared, followed by polymerization of styrene, allowing us to obtain a uniformly dispersed PS/RC composite. When the RC concentration was above 0.8 wt%, a network of RC spontaneously formed in the composite, as evidenced by rheological testing. Furthermore, the addition of RC to polystyrene improved the composite's thermal stability and tensile mechanical properties while minimally impacting average visible light transmission (with a decrease in average transmission by about 1-5%). Regenerated cellulose is a promising nanofiller for polymeric composites due to its environment friendly and cost effective nature, and could be used for preparation of other novel RC-reinforced composites.

Pickering emulsion process assisted construction of regenerated chitin reinforced poly (lactic acid) blends.

Regenerated chitin (RCh)/poly (lactic acid) (PLA) blends with enhanced properties were successfully prepared via the Pickering emulsion approach. An oil-in-water Pickering emulsion of PLA/dichloromethane (DCM) stabilized with RCh via an ultrasonic homogenizer was formed. A uniformly dispersed blends were obtained upon slow volatilization of DCM. The effects of RCh on physical/morphological, thermal, mechanical and rheology properties of the blends were studied. The introduction of RCh in PLA improved its crystallinity from 23.4% to over 38.0%. The blends displayed an improvement in storage modulus of 393% at 70 °C for 2 wt%RCh as compared with neat PLA. The RCh/PLA blends showed an enhancement in both tensile strength and elongation at break of 18% and 31% respectively at the loading of 1.5 wt%-RCh. Moreover, the complex viscosity of the blends was increased compared to neat PLA, and all the blends exhibited shear-thinning behaviour without any plateau region at low angular frequencies (ω < 10 rad/s). These results suggest that the low weight content RCh introduced to PLA matrix via this facile Pickering emulsion approach not only promotes nucleation in RCh/PLA blends but also acts as a promising reinforcing agent for PLA.

Poly(lactic acid)/cellulose nanocrystal composites via the Pickering emulsion approach: Rheological, thermal and mechanical properties.

The use of nanocellulose is an attractive method to improve the characteristics of biodegradable polymers, but its effects are often affected by uneven dispersion. In this work, cellulose nanocrystals (CNCs) were evenly dispersed into poly(lactic acid) (PLA) via the Pickering emulsion approach. The PLA/CNC composites prepared were studied by rheological, thermal as well as mechanical measurements. Changes in the rheological characteristics of the composites showed that CNC promoted the transition of the composites from fluid to solid-like behavior at high temperatures. The introduction of 5 wt% CNC improved the crystallinity of PLA considerably and increased the onset temperature of crystallization by about 10 °C. The storage modulus of the composites increased throughout the entire temperature range of testing. Flexural modulus was improved considerably. All the results indicated that the Pickering emulsion approach improved the dispersion of CNC in the PLA matrix and CNC improved efficiently most properties of PLA.

Oil-in-water Pickering emulsions from three plant-derived regenerated celluloses.

Regenerated cellulose (RC) has attracted interest for stabilizing emulsions effectively via both Pickering and networking mechanisms. In this study, RCs were prepared from three plant-derived celluloses (wood pulp, bamboo pulp and cotton fabric). The three RCs had similar morphological networks, but their viscosities were 0.55 Pa s, 1.47 Pa s and 2.29 Pa s, respectively. The properties of Pickering emulsions stabilized by the RCs were investigated. The results revealed that the droplet sizes and viscosities of the three emulsions varied. After seven days of storage, the droplet sizes of the emulsions remained unchanged, but the viscosities of the emulsions from wood pulp, bamboo pulp and cotton fabric increased by 163%, 115% and 9%, respectively. These findings demonstrate that the source of RC plays an important role in determining the properties of the resulting suspensions and emulsions, thereby providing guidelines for the preparation of RC-based green emulsions for applications in cosmetics and related formulations.

Biodegradable regenerated cellulose-dispersed composites with improved properties via a pickering emulsion process.

Reinforcement of biodegradable polymers with nanocellulose is attractive yet the effectiveness is often compromised by uneven dispersion. In this work, a general method of preparing reinforced biodegradable composites using regenerated cellulose (RC) was developed. From an oil-in-water Pickering emulsion of PLA/methylene chloride stabilized with RC, uniformly dispersed RC/PLA composites was obtained. The resulting RC/PLA composites showed enhanced crystallization and tensile strength of up to 34% compared with the native PLA, while the transmittance in the visible range remained above 70%. The Pickering emulsion-based composition procedure is simple, environment friendly and cost effectively, which could be applied to preparation of other RC-reinforced biodegradable composites.