Packaging and degradability properties of polyvinyl alcohol/gelatin nanocomposite films filled water hyacinth cellulose nanocrystals

Cellulose nanocrystals isolated from water hyacinth fiber(WHF)have been studied as a reinforcement for polyvinyl alcohol(PVA)-gelatin nanocomposite.Central composite design was used to study and optimize effects of the PVA,gelatin and cellulose nanocrystal(CNC)concentration on tensile strength and elongation of formed films.The results of this study showed that WHF CNC had a diameter range of 20-50 nm produced films reaching 13.8 MPa tensile strength.Thermal stability of the films was improved from 380℃ to 385℃ in addition of CNCs and maximum storage modulus of 3 GPa were observed when 5 wt%CNC was incorporated.However,water absorption,water vapour permeability(WVP)and moisture uptake of the films decreased in addition of CNC to the PVA-gelatin blends.Moisture uptake decreased from 22.50%to 19.05%while the least WVP when 10 wt%CNC added was 1.64×10^(-6)g/(m·h·Pa).These results show possibility for industrial application of WHF CNC and PVA-gelatin blends in biodegradable films for on-the-go food wrappers.

Generation of Tough Poly(glycolic acid)(PGA)/Poly(butylene succinate-co-butylene adipate)(PBSA)Films with High Gas Barrier Performance through In situ Nanofibrillation of PBSA under an Elongational Flow Field

Poly(glycolic acid)(PGA)is derived from glycolide obtained by fermenting pineapples or sugarcane,which has excellent gas barrier properties and a small carbon footprint.PGA is a potential substitute for the current aluminum-plastic composite films used in high barrier packaging applications.However,its poor ductility and narrow processing window limit its application in food packaging.Herein,poly(butylene succinate-co-butylene adipate)(PBSA)was used to fabricate PGA/PBSA blend films through an in situ fibrillation technique and blown film extrusion.Under the elongational flow field used during the extrusion process,a unique hierarchical structure based on the PBSA nanofibrils and interfacially oriented PGA crystals was obtained.This structure enhances the strength,ductility and gas barrier properties of the PGA/PBSA blend film.In addition,an epoxy chain extender(ADR4468)was used as a compatibilizer to further enhance the interfacial adhesion between PGA and PBSA.70PGA/0.7ADR exhibited a very low oxygen permeability(2.34×10^(-4)Barrer)with significantly high elongating at break(604.4%),tensile strength(47.4 MPa),and transparency,which were superior to those of petroleum-based polymers.Thus,the 70PGA/0.7ADR blown films could satisfy the requirements for most instant foods such as coffee,peanuts,and fresh meat.

High-strength collagen/delphinidin film incorporated with Vaccinium oxycoccus pigment for active and intelligent food packaging

This study developed an active and intelligent collagen-based packaging film with high strength for visually monitoring the freshness of fish.The results of scanning electron microscopy and atomic force microscopy showed that the film based on cross-linked collagen/delphinidin catalyzed by laccase exhibited a denser layer structure and a rougher surface.The dry and wet tensile strengths of the laccase-catalyzed collagen/delphinidin film(Col/Dp-LA film)increased by 41.74 MPa and 13.13 MPa in comparison with that of the pure collagen film,respectively.Moreover,the Col/Dp-LA film presented good antioxidant and barrier properties demonstrated by the results of free radical scavenging rate,light transmission rate,and water vapor permeability.The intelligent collagen-based film was obtained by incorporating Vaccinium oxycoccus pigment into the Col/Dp-LA film,which could change color under different pH values.When applied to the preservation offish fillets,the film could release Dp to minimize oxidative rancidity and prolong the shelf life of the fish for 2 days.Meanwhile,the film showed visual color changes from purplish-red to greyish-blue after the fish spoilage.These results indicated that the collagen film treated with delphinidin,laccase,and Vaccinium oxycoccus pigment has potential application value in the field of active and intelligent food packaging.

A novel edible packaging film based on chitosan incorporated with persimmon peel extract for the postharvest preservation of banana

This study aimed to develop a novel edible packaging film for the postharvest preservation of banana based on chitosan(CS)and persimmon peel extract(PPE).Scanning electron microscopy analysis showed that PPE was evenly distributed in the CS matrix and Fourier transform infrared spectroscopy analysis showed that CS and PPE interacted to form hydrogen bonds,demonstrating good compatibility.Simultaneously,the addition of PPE also significantly improved the physical properties and antioxidant activity of the CS film.Among them,the CS film containing 10%PPE(CS-PPE 10)showed the optimal mechanical properties,water vapor barrier properties and oxygen barrier properties.The CS film containing 15%PPE(CS-PPE 15)exhibited the best thermal stability,UV-Vis barrier properties and antioxidant activity.In the experiment on banana preservation,CS-PPE 10 film obtained optimal performance on decreasing senescence spots,weight loss,fruit softening,and cell wall degradation,inhibiting the activities of polyphenol oxidase and cell wall-degrading enzymes and maintaining the content of total soluble sugar and ascorbic acid during the storage period.Consequently,CS-PPE 10 film was expected to be a novel edible packaging material to maintain banana quality and prolong shelf life.

Experiment and optimal design of a collection device for a residual plastic film baler

It is imperative to carry out research on residual plastic film collection technology to solve the serious problem of farmland pollution.The residual plastic film baler was designed as a package for film strip collection,cleaning and baling.The collection device is a core component of the baler.Response surface analysis was used in this study to optimize the structure and working parameters for improving the collection efficiency of residual film and the impurity of film package.The results show that the factors affecting the collection rate of residual film and the impurity of the film package are the speed ratio(k)between the trash removal roller and eccentric collection mechanism,the number(z)and the mounting angle(θ)of spring teeth in the same revolution plane.For the collection rate,the importance of the three factors are in the order,k>z>θ.Meanwhile,for the impurity,the importance of three factors are in the order,z>k>θ.When the speed ratio,the mounting angle and the number of spring teeth was set at 1.6°,45°,and 8°,respectively,the collection rate of residual film was 88.9%and the impurity of residual film package was 14.2%for the baler.