Synergism of Zinc Oxide/Organoclay-Loaded Poly(lactic acid) Hybrid Nanocomposite Plasticized by Triacetin for Sustainable Active Food Packaging

The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.

The interaction of nanostructured antimicrobials with biological systems:Cellular uptake,trafficking and potential toxicity

Nanomaterials have been found increasing applications in the food sector.Nanostructured antimicrobials can be incorporated either to food matrix of food packaging or to provide extended safety and quality.However,the interactions and effects of nanomaterials with biological systems are still poorly understood.Nanoparticles can enter the organism by oral,dermal and inhalation routes and distributed to different tissues by the circulatory system.Increasing evidence indicate that targeting to specific tissues,cellular uptake and intracellular fate of nanoparticles are strongly influenced by size,shape and surface properties.The specific characteristics of nanomaterials are also determinant for their toxicity in higher organisms.The dose,exposure time and administration route are important aspects influencing toxicity of nanoparticles as well.Both in vitro and in vivo evaluation studies on different types of nanostructures have providing information to support a better understanding about the interactions of nanoscale materials with biological systems.

Electrospun gelatin/chitosan nanofibers containing curcumin for multifunctional food packaging

Recently,food grade nanofiber-based materials have received growing attentions in food packaging.In this work,novel active and intelligent packaging nanofibers based on gelatin/chitosan with curcumin(GA/CS/CUR)were developed via electrospinning technique.Effects of the incorporation of CUR content(0.1%-0.3%,m/m)on the microstructure and functional properties of the electrospun nanofibers were investigated.Morphological studies using scanning electron microscopy indicated that loading CUR can affect the average diameter of nanofiber mats,which remained around 160-180 nm.The addition of an appropriate level CUR(0.2%,m/m)led to a stronger intermolecular interaction,and thus enhanced the thermal stability and tensile strength of the obtained nanofibers.Meanwhile,the incorporation of CUR significantly improved antioxidant activity and the antimicrobial activity of GA/CS/CUR nanofibers.Moreover,the sensitivity of nanofibers to ammonia results indicated that GA/CS nanofibers containing 0.2%CUR(GA/CS/CURⅡ)presented high sensitivity of colorimetric behavior to ammonia(within 3 min).These results suggest GA/CS/CURⅡnanofibers has great potential as a multifunctional packaging to protect and monitor the freshness of proteinrich animal foods,such as meat and seafood.

Starch/agar-based functional films integrated with enoki mushroom-mediated silver nanoparticles for active packaging applications

Silver nanoparticles(AgNPs)were manufactured using the green method mediated by enoki mushroom water extract,and starch/agar functional films were fabricated.The developed AgNPs were small(~10 nm)and spherical and showed strong antibacterial activity towards foodborne pathogenic bacteria,L.monocytogenes,and E.coli.AgNPs were unvaryingly dispersed in the starch/agar matrix,and the inclusion of AgNPs pointedly enhanced the water vapor barrier and hydrophobicity of the starch/agar-based films.However,adding AgNPs did not affect the films’mechanical strength and thermal stability.Also,the AgNPs-added starch/agar film displayed potent antibacterial activity towards E.coli and L.monocytogenes.Starch/agar films with better physical(mechanical strength,water vapor barrier)and functional properties(antibacterial activity)are expected to be applied in active food packaging.

Development of Ficus carica Linn leaves extract incorporated chitosan films for active food packaging materials and investigation of their properties

The serious problems caused by extensive usage of petroleum-based plastic materials led to investigating the comprehensive studies and developing active food packaging materials.Even if the chitosan-based films are considered an attractive source,they exhibit some practical difficulties in developing active food packaging applications.Hence,Ficus carica Linn leaves extract(FLE),with the features of its cheapness,easy accessibility and superoxide anion radical scavenging activity,was incorporated into chitosan(CS)film at various concentrations(2%-6%w/w).To the best of our knowledge,this was the first time that FLE was utilized as a bioactive substance incorporated into chitosan films to develop eco-friendly,biodegradable,active food packaging material.The results obtained revealed that FLE incorporation into chitosan films significantly improved the swelling,water solubility and opacity of neat chitosan films.FTIR and morphological analysis indicated that the films produced exhibited smooth structure with homogenous dispersion of FLE.In mechanically,the addition of FLE resulted in a significant reduction in tensile strength while the elasticity of the films was improved.Additionally,the antioxidant and biodegradability properties of neat chitosan films were enhanced significantly.It was concluded that CS-FLE films appeared to be a capable and enhanced option for synthetic polymer-based food packaging materials.Based on the analyses performed,further studies are suggested on the packaging application for various foods and to evaluate the possible interaction of packaging film materials with the compounds of the food products,to avoid possible negative effects.

Anthocyanins/chitosan films doped by nano zinc oxide for active and intelligent packaging:comparison of anthocyanins source from purple tomato or black wolfberry

The multifunctional films was prepared by blending chitosan and nano-ZnO with purple tomato anthocyanins or black wolfberry anthocyanins.The properties of films functioned by anthocyanins source and nano-ZnO content were studied.It was found purple tomato anthocyanins showed more significant color change against pH than black wolfberry anthocyanins.The nano-ZnO were widely dispersed in matrix and enhanced the compatibility of anthocyanins with chitosan.However,the anthocyanins source influenced the properties of the films more slightly than nano-ZnO addition.The tensile strength,antioxidant and antibacterial effects of the chitosan films dramatically increased after cooperated by nano-ZnO and anthocyanins,which also enhanced with increase of nano-ZnO content,whereas the elongation at break of the composite films decreased.Especially,the anthocyanin and nano-ZnO promoted the antibacterial activity of films synergistically.Composite films made from black wolfberry anthocyanins exhibited higher mechanical performance than those made from purple tomato anthocyanins but weaker antibacterial effects.The purple tomato anthocyanins/chitosan and nano-ZnO/purple tomato anthocyanins/chitosan films effectively reflected pork spoilage,changing their colors from dark green to brown,indicating the potential for applications in active and intelligent food packaging.

Antioxidant Migration Studies in Chitosan Films Incorporated with Plant Extracts

The aim of this work was to develop an active biopolymer based on chitosan by incorporating natural antioxidants.Five essential oils(ginger,rosemary,sage,tea tree and thyme)and six hydro-alcoholic extracts(from ginger,green and black tea,kenaf leaves,rosemary and sage plants)were tested.Migration assays were carried out to evaluate the films’activity,and total phenolic content and antioxidant activity were monitored in the simulant during storage.Interaction between natural compounds and polymeric matrix was evaluated by FTIR spectroscopy.The diffusion of the phenolic compounds was not detected in the films incorporated with hydro-alcoholic extracts(HAEs),indicating their entrapment in the chitosan.Migration was observed in the films with essential oils(EOs),and biobased films incorporated with ginger,sage or rosemary essential oils,presented the highest diffusion and antioxidant activity in the simulant,highlighting their functionality and potential to be used as food active packaging material.

Comparison of eugenol and dihydromyricetin loaded nanofibers by electro-blowing spinning for active packaging

To explore the dihydromyricetin or eugenol loaded nanofiber’s potential as food active packaging,0%,0.1%,0.5%,and 1.0%dihydromyricetin or eugenol loaded nanofibers were fabricated by electro-blowing spinning,which increased the yield of nanofibers by a factor of 10 times compared to that of traditional electrospinning.The morphology observation by scanning electron microscopy showed similar morphology and diameter distribution of the dihydromyricetin or eugenol nanofibers.Fourier transform infrared spectra analysis indicated that eugenol or dihydromyricetin interacted with proteins through hydrogen bonding.X-ray diffraction profiles of the nanofibers indicated that dihydromyricetin was uniformly distributed within the nanofibers.Nanofibers encapsulated with various concentrations of eugenol or dihydromyricetin showed better barrier properties against water vapors than the free nanofibers,which indicated that the hydrophobic eugenol and dihydromyricetin inhibited the permeation of water molecules through the nanofibers.Tensile tests showed that the nanofibers loaded with 0.5%eugenol or 1.0%dihydromyricetin exhibited relatively higher elastic moduli and lower elongation at break.The nanofibers loaded with dihydromyricetin showed comparable antioxidant activity to that with eugenol in the aspect of ferric and cupper reducing activity,while that with 0.1%-1.0%dihydromyricetin showed superior DPPH radical scavenging activity.Furthermore,both eugenol and dihydromyricetin loaded gelatin/zein nanofibers showed effective antimicrobial activities against Escherichia coli and Staphylococcus aureus.Overall,the dihydromyricetin loaded gelatin/zein nanofibers showed comparable physical and functional properties compared to eugenol,which suggests the application of dihydromyricetin nanofibrous films on food active packaging and the potential application of dihydromyricetin on functional food delivery systems.

Active packaging of chitosan film modified with basil oil encapsulated in silica nanoparticles as an alternate for plastic packaging materials

Active packaging based on biomaterials and essential oils is an alternate for plastic ones.But,essential oils are chemically and physiologically labile,and they have strong scents,limiting their use as antimicrobial additives in food.Thus,in this investigation,basil oil was encapsulated in silica nanoparticles(basil oil@SiNPs)and combined with chitosan films(basil oil@SiNPs@chitosan).Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),X-ray diffraction(XRD),surface area and Brunauer-Emmett-Teller(BET)analysis,encapsulation and loading%were used to evaluate basil oil@SiNPs.The surface area of SiNPs decreased from 59.006 to 43.86 cm^(2)/g due to basil oil encapsulation.The encapsulation and loading%were 81.96,65.87,48.48 and 43.13,37.64,33.44%for 2,1.5,and 1 mL of basil oil,respectively.Fourier-transform infrared(FT-IR),XRD,thermogravimetric analysis(TG),mechanical,wettability,water vapor permeability(WVP),oxygen permeability(OP)features;water vapor sorption isotherms and antimicrobial inhibition tests were used to describe the produced basil oil@SiNPs@chitosan films.Water contact angles and activation energy increased from 89.0◦to 110.9◦and-11.97 to-20.40 kJ/mol,respectively after addition of basil oil@SiNPs.However,WVP decreased from 5.9580×10^(-1)±0.33 to 4.2413×10^(-1)±0.55 g.mm.m^(-2).h^(-1).kPa^(-1)and OP increased from 4.094×10^(-4)±0.52 to 6.715×10^(-5)±0.32(g.m^(-2).day^(-1).atm^(-1)).The four models Guggenheim-Anderson-de Boer(GAB),Smith,Henderson and SIPSI were suitable for describing the moisture sorption of basil oil@SiNPs@chitosan films.Basil oil@SiNPs has antimicrobial inhibition against Gram positive and negative bacteria,pathogenic yeast.

Antilisterial action of PLA films with ferulic acid as affected by the method of incorporation

Previous studies demonstrated that polylactic acid (PLA) films with ferulic acid (F) obtained by melt blending did not release the active compound to exert effective antibacterial action. To solve this problem, different strategies to promote the active properties of PLA-F materials have been studied: film processing by casting with F up to 10% w/w, surface loading of thermoprocessed films with F, by adsorption or pulverisation with F solutions, and electrospinning of PLA-F solutions, using different solvent systems, to obtain nanostructured mats. The materials obtained were characterised by their morphological properties and antilisterial activity. F crystallised inside cast films and on the surface loaded PLA films. Electrospun materials exhibited different morphology, depending on the solvent system of the initial solution;fibre mats were obtained with ethyl acetate-DMSO mixtures, whereas bead structures were mainly formed with glacial acetic acid with or without ethyl acetate. No antilisterial activity was observed in cast films regardless of the F concentration, whereas surface loaded films by adsorption or pulverisation inhibited the listeria growth by about 4 Log (CFU/mL). Electrospun materials only inhibited bacterial growth (3 Log CFU) when these were fibre-structured. Therefore, active films of PLA with F could be only obtained when the active was surface anchored or encapsulated in thin fibre mats, with high surface to volume ratio. In this way, the release of the active compound is promoted, avoiding the problem of its limited internal diffusion through the PLA matrix.

The modification effects of roselle anthocyanin film on shrimp texture via water distribution controlling and protein conformation maintenance

The food’s perishable properties and people’s eco-friendly requirements have driven the biodegradable active packaging development.In this study,modification behaviors of polyviniyl alcohol/hydroxypropyl methylcellulose/roselle anthocyanin-based(PHR)film on textural profiles of Penaeus vannamei were investigated.Shrimp samples were packaged by PHR film with different roselle anthocyanin contents and stored at 4±1℃.The results indicated that PHR groups exhibited better texture with higher values of hardness(435.56±75.52 g),springiness(0.53±0.04 mm),chewiness(198.83±40.98 N)and resilience(0.45±0.04).The PHR film exerted positive influences on water migration by reducing drip loss and promoting conversion of free water into immobilized water.Meanwhile,the PHR film retarded protein denaturation via increasing myofibrillar protein and sulfhydryl group contents,decreasing TCA(trichloroacetic acid)-soluble peptide contents and maintaining protein secondary structure(higherα-helix ratio and lowerβ-sheet ratio).In conclusion,the PHR film improved shrimp texture by rearrangement of water distribution and stabilization of protein conformation.Hence,the PHR film was a novel potential active packaging for shrimp texture enhancement.

Antioxidant and antimicrobial packaging films developed based on the peel powder of different citrus fruits:A comparative study

Citrus is the largest fruit crop planted worldwide.However,the global citrus fruit processing byproducts have not been fully utilized up to now.Citrus peels contain valuable biopolymers and bioactive substances,which are suitable to develop food packaging films.In this study,active packaging films were prepared by directly utilizing citrus peels in their powder form.The films produced from the peel powder of four different citrus fruits(orange,lemon,pomelo and mandarin)were compared for their structural and functional properties.Results showed the four kinds of citrus peel powder contained 16.36%-23.80%pectin,5.68%-8.23%protein,3.17%-7.65%lipid,2.88%-6.27%crude fiber and 11.45-15.47 mg GAE/g polyphenols.Four kinds of citrus peel powder based films exhibited rough surface and transverse with yellow or flesh color.These films had 0.124-0.157 mm of thickness,18.16%-25.25%of moisture content,51.98-121.64°of water contact angel,1.34-1.92×10^(-1)0 g m^(-1)s^(-1)Pa^(-1)of water vapor permeability,0.36-0.69 cm^(3)mm m^(-2)day^(-1)atm^(-1)of oxygen permeability,8.26-9.14 MPa of tensile strength and 8.05%-17.18%of elongation at break.These films also showed strong antioxidant and antimicrobial activity,which retarded corn oil oxidation.Among the films,mandarin peel powder based film was most effective in retarding oil oxidation due to the excellent light and oxygen barrier capacity and antioxidant activity of the film.Results suggested mandarin peel powder based film was suitable for the active packaging of corn oil.

Ethylene scavenging film based on corn starch-gum acacia impregnated with sepiolite clay and its effect on quality of fresh broccoli florets

Barley(Hordeum vulgare L.)grasses(BG)have attracted considerable interest due to their multiple physiological activities and health benefits.In this paper,eight BG at four different growth stages were collected:seedling,tillering,stem elongation,and heading,and their product qualities and biological activities were examined and studied.Results demonstrated that harvest time obviously influenced proximate composition,surface color,and amino acid profile.Z21 and Z23 harvested at the seedling and early tillering stages,respectively,had higher total phenolic content(TPC)and total flavonoid content(TFC)than the other BG.Moreover,Z21 and Z23 possessed better DPPH radical-scavenging ability,antioxidant capacity,andα-glucosidase inhibitory activity,which were positively correlated with TPC,TFC,and protein and total amino acid contents.Our findings suggested that the early tillering stages were the preferable harvest times for BG with good product quality and biological properties.

Evidence on antimicrobial activity of essential oils and herbal extracts against Yersinia enterocolitica - A review

Yersinia enterocolitica is a very common food-borne pathogen which causes gastrointestinal infections (yersiniosis) in humans and a wide array of animals (e.g.cattle,deer,pigs,and birds).Due to the increasing interest in innovative plant-based substances as common food preservatives,several essential oils and herbal extracts have been investigated deeply that resulted in the emergence of novel anti-Yersinia additives.We reviewed relevant work done by 53 researchers covering literature from the year 2002 to till date.Some species such as Origanum vulgare ,Rosmarinus officinalis ,Thymus vulgaris ,Ocimum basilicum have been extensively investigated and identified that 1,8-cineole,linalool and γ-terpinene as compounds found in the essential oils of these plants have anti-Yersinia activity active food packaging agents.In the same direction,some promising results have been mentioned about the herbal extracts of Murrya koenigii ,Tanacetum vulgare and Tanacetum balsamita,but further investigations are needed for their sustainable implications.According to hierarchical cluster analysis,we found that Lamiaceae and Lauracea as the most significant families with anti-Yersinia activity.Towards the end,we proposed new research trends in order to enhance a global knowledge about the use of natural products against Y.enterocolitica .