Yuyue Qin

Effect of chitosan film incorporated with tea polyphenol on quality and shelf life of pork meat patties.

The objective of this study was to investigate the effect of chitosan (CH) film incorporated with tea polyphenol (TP) on quality and shelf life of pork meat patties stored at 4±1 °C for 12 days. The microbiological, physicochemical (pH, thiobarbituric acid-reactive substances (TBARS) values, and metmyoglobin (MetMb)), and sensory qualities were measured on all the samples. A microbiological shelf-life extension of 6 days was achieved for CH and CH-TP treatment groups when compared to the control group. Wrapping with CH-TP composite film tended to retard the increases in TBARS values and MetMb content. CH-TP composite film maintained acceptable sensory quality of pork meat patties throughout the storage. The results indicated that CH-TP composite film could be a promising material as a packaging film for extending the shelf life of pork meat patties.

Effects of N-octyl lactate as plasticizer on the thermal and functional properties of extruded PLA-based films.

Films of poly(l-lactide) (PLA) plasticized with varying levels of N-octyl lactate (NOL) were prepared by extrusion. The thermal and functional properties of the blends were investigated by SEM, DSC, TGA, tensile, opacity, water vapor permeability, and water contact angle tests. The compatibility of the plasticizer with PLA was confirmed by DSC and SEM analysis. A higher plasticizing effect on the thermal properties of PLA was generally observed with the increase in NOL content. Additionally, the mechanical properties were improved with the increase in NOL content. The mechanical resistance of the films could be related to their glass transition temperature. The effect of the concentration of plasticizer on the opacity of the films was negligible. The water vapor permeability of the PLA/NOL composite films increased with the increase in the concentration of NOL; however, the values observed were still lower than the water vapor permeability of commercial LDPE films. In conclusion, the extruded PLA-based films with NOL plasticizers could be used as food-packaging materials.

Formulation and evaluation of in situ forming PLA implant containing tinidazole for the treatment of periodontitis.

Periodontitis is caused by periodontopathic bacteria and antibacterial agents are placed in a periodontal pocket with the intention of enhancing the local effect. To maximize the therapeutic effects while reducing the adverse effects, tinidazole was delivered by in situ forming system. One approach for reducing burst release rate was to testify in situ forming effect. The effect of 0%-10% (w/w) polyethylene glycol 400 and 3% (w/w) glycerol on the tinidazole release from a poly(DL-lactide) (PLA) injectable implant was evaluated. The results showed that the in vitro initial burst release rate was decreased in the presence of poly(ethyleneglycol) PEG 400 and glycerol. A formulation containing 30% (w/w) PLA (M(w) 7300) dissolved in 62% (w/w) N-methyl-2-pyrrolidone, 5% (w/w) PEG 400, and 3%(w/w) glycerol with 5% (w/w) tinidazole was shown to be optimum. Twelve adult beagle dogs were used in the periodontitis model. The treatment group I, II, and positive control group was administrated with gel containing 5%(w/w) tinidazole, 2.5%(w/w) tinidazole, and periocline, respectively. Dog studies revealed that periocline and the developed formulation could significantly decrease symptoms of periodontitis, and they were better than gel containing 2.5% (w/w) tinidazole. The developed formulation could sustain the release of tinidazole for local delivery over 7 days. These findings suggested that the developed formulation was a viable alternative to conventional drug to cure periodontitis.

Development of Antimicrobial Packaging Film Made from Poly(Lactic Acid) Incorporating Titanium Dioxide and Silver Nanoparticles

Polylactide (PLA)/nano-TiO2 and PLA/nano-TiO2/nano-Ag blends films were prepared by a solvent volatilization method. Compared to pure PLA film, the nano-blend films have low water vapor permeability (WVP) and a poor transparency. With the increase of the NPs in the PLA, the tensile strength (TS) and elastic modulus (EM) decreased, while the elongation at break (ε) increased. SEM analysis indicated a rougher cross-section of the nano-blend films. According to the FTIR analysis, no new chemical bonds were formed in the nano-blend films. By using DSC to examine the crystallization and melting behavior, the result shows that the NPs have no effect on the glass transition (Tg) and melting temperature (Tm), but they caused an increase on the cold crystallization (Tc) and crystallinity (Xc). TGA results show that the addition of nanoparticles significantly improved the thermal stability. The PLA nano-blend films show a good antimicrobial activity against. E. coli and Listeria monocytogenes. Most important, we carried out migration tests, and verified that the release of NPs from the nano-blend films was within the standard limits.

Preparation and characterization of poly(l-lactide)-co-poly(trimethylene carbonate)/talc film

Poly(L-lactide)-co-poly(trimethylene carbonate) (PLLA-PTMC) composites with various talc content as food packaging materials were prepared by solvent casting method. The effect of talc filler loading (0, 1, 2, and 3 wt%) on phase morphology of PLLA-PTMC/Talc composites and improvement in resulting properties were reported. The X-ray diffraction (XRD) patterns and differential scanning calorimetry (DSC) curves indicated that the crystallinity of PLLA-PTMC/Talc composites increased. Fourier transform infrared spectroscopy (FTIR) suggested that there were strong interactions between PLLA-PTMC copolymer and talc filler. The scanning electron microscopy (SEM) image of composite films revealed certain homogeneity between PLLA-PTMC and Talc, when the talc filler did not exceed 3 wt%. The elongation at break of composite films significantly (p<0.05) improved with the addition of talc filler. Furthermore, there were 23%, 31%, and 14% improvement in water vapor barrier properties at 1, 2, and 3 wt% of talc in PLLA-PTMC/Talc composites, respectively. This had been confirmed by thermogravimetric analysis (TGA).

Effects of PLA Film Incorporated with ZnO Nanoparticle on the Quality Attributes of Fresh-Cut Apple

A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (ε) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce.

Physicochemical Properties and Microbial Quality of Tremella aurantialba Packed in Antimicrobial Composite Films

The effects of poly(lactic acid) (PLA)-based film with inorganic antimicrobial nano-TiO2 and nano-Ag on the physicochemical and microbial quality of Tremella aurantialba stored at 4 ± 1 °C for 16 days was investigated. Rosemary essential oil (REO, 9 wt %) was added into PLA film as plasticizer. Low-density polyethylene (LDPE) and PLA film was used as the controls. The experiment measured physicochemical properties and microbial levels, such as weight loss, firmness, vitamin C, color, microbiological quality, and sensory quality. Although Tremella aurantialba packed by nano-composite films had the highest weight loss (4.96% and 5.17%) at the end of storage, it was still in the vicinity of 5%. Tremella aurantialba packed with nano-composite films were significantly (p < 0.05) firmer than those packed by LDPE, PLA, and PLA/REO films. The nano-composite films were more effective in reducing vitamin C and microbial counts and preserving the color of Tremella aurantialba than the other three groups. The overall acceptability of Tremella aurantialba packed by the nano-composite films still remained good and within the limits of marketability after 12 days of storage. The results suggested that the proposed nano-composite films could maintain the quality of Tremella aurantialba and extend its postharvest life.

High Pressure Treatment for Improving Water Vapour Barrier Properties of Poly(lactic acid)/Ag Nanocomposite Films

Effects of high pressure treatment (0, 200 and 400 MPa) on water vapour barrier, microstructure, thermal, and mechanical properties of poly (lactic acid) (PLA)/Ag nanocomposite films were investigated. The migration behavior of nano-Ag from the nanocomposite films in the presence of 50% (v/v) ethanol as a food simulant was also studied. The water vapour barrier properties increased as pressure was applied to film-forming solutions. High pressure treatment enhanced the mutual effect between PLA and nanoparticles, leading to a more compact network structure in PLA/Ag nanocomposite films. Furthermore, PLA/Ag nanocomposite films treated by high pressure were significantly affected by microstructure, thermal, and mechanical properties when, compared with untreated samples. High pressure treatment at 200 to 400 MPa significantly (p < 0.05) reduced the migration of nano-Ag from the films. Overall, high pressure treatment on film-forming solutions showed potential in improving the functional properties of nanocomposite films, especially in relation to water vapour barrier properties.

The Quality Evaluation of Postharvest Strawberries Stored in Nano-Ag Packages at Refrigeration Temperature

Different percentages (0%, 1%, 5%, and 10%) of nano-Ag particles were added to polylactic acid (PLA) to make an active nanocomposite packaging film. Strawberries were packaged by the nanocomposite films and stored at 4 ± 1 °C for 10 days. The freshness of strawberries was assessed by regularly measuring the physicochemical properties of the strawberries in each packaging film. The difference in the freshness of strawberries was evaluated by determining the following parameter changes: weight loss, hardness, soluble solids, titratable acid, color, vitamin C, total phenol, free radical scavenging activity, peroxidase activity, and sensory evaluation. The results revealed that the active nanocomposite packaging film has better preservation effect when compared with pure PLA film. Its preservation effect is mainly reflected in the more effective reduction of vitamin C loss, delaying the decline of total phenols and 1-Diphenyl-2-picrylhydrazyl (DPPH) in strawberries. It also showed better physical properties. The results showed that the PLA nanocomposite packaging film could effectively preserve freshness of strawberries.

Effect of High Pressure Treatment on Poly(lactic acid)/Nano–TiO2 Composite Films

The microstructure, thermal properties, mechanical properties and oxygen and water vapor barrier properties of a poly(lactic acid) (PLA)/nano-TiO2 composite film before and after high pressure treatment were studied. Structural analysis showed that the functional group structure of the high pressure treated composite film did not change. It was found that the high pressure treatment did not form new chemical bonds between the nanoparticles and the PLA. The micro-section of the composite film after high pressure treatment became very rough, and the structure was depressed. Through the analysis of thermal and mechanical properties, high pressure treatment can not only increase the strength and stiffness of the composite film, but also increase the crystallinity of the composite film. Through the analysis of barrier properties, it is found that the barrier properties of composite films after high pressure treatment were been improved by the applied high pressure treatment.