Active Bio-composite Sodium Alginate/Maltodextrin Packaging Films for Food Containing Azolla pinnata Leaves Extract as Natural Antioxidant

The aim of the current work was to produce sodium alginate (SA) maltodextrins (MD) based functional films incorporated with phenolic extract of Azolla pinnata leaves fern (AF) by solution molding technique. AF with different concentrations (0.8, 1.2 and 1.6% w/w) were integrated inside SA.MD films. The resulted films were characterized to investigate the surface structure by scanning electron microscope (SEM), thermal disposal by (DSC), crystallization by X-ray diffraction (XRD), potential interaction by (FT-IR) and some mechanical properties. The SEM micrographs indicated that the higher concentration (1.6%) of AF extract caused development of wrinkles on the surface of films. And as a result, there were a significant decrease of elongation at break (EB) and tensile strength properties of films to 55.01 and 58.42%, respectively. By continues addition of AF extract to SA.MD films, the film thickness increased from 0.124 to 0.181 mm, the scavenging and antimicrobial properties were enhanced by the attendance of ferulic acid, rutin, thiamine, tamarixetin, astragalin, quercetin, chlorogenic acid and epicatechin inside extracts. Furthermore, the films solubility, swelling degree and water vapor permeability were decreased to 13.08%, 26.41% and 1.662?×?10^??10 g H₂O/m s p.a. The resulted films could be utilized as composite packaging material for different food applications.

     

Nanocomposite Film Based on Gluten Modified with Heracleum persicum Essence/MgO/Polypyrrole: Investigation of Physicochemical and Electrical Properties

In this study, the wheat gluten film was prepared. Heracleum persicum essence, magnesium oxide nanoparticles and polypyrrole were used to modify the structure of the wheat gluten film. Physicochemical properties of the prepared films such as thickness, solubility, moisture absorption ability, antioxidant properties, and electrical conductivity of the films were investigated. Also, the mechanical, structural and thermal properties of the films were investigated by techniques such as SEM, FTIR, XRD, TGA, DTA and tissue analysis. SEM images showed that the essence and polypyrrole strengthened the gluten film structure and made it more resistant to the passage of gases. FTIR spectra confirmed the electrostatic interactions between gluten and essence and polypyrrole. XRD spectra showed the amorphous structure of gluten film and its composites. The results of thermal analysis showed that polypyrrole greatly increased the thermal resistance of the film and the nanoparticles had little effect on the thermal resistance. Thickness, solubility, moisture content and ability to absorb moisture were further affected by the essential oil. The antioxidant and electrical conductivity of the film was greatly increased in the presence of all three additives of essence, magnesium oxide nanoparticles and polypyrrole. The gluten–essence–MgO–PPy (Glu–E–MgO–PPy) composite film had the most antioxidant properties. Glu–E–MgO–PPy film with important electrical conductivity and antioxidant properties has the potential to be used as an active and intelligent film in the packaging of perishable food products.

     

Preparation and Properties of Propylene Glycol Plasticized Wheat Protein Isolate Novel Green Films

Novel bio-based green films were prepared using wheat protein isolate (WPI) by solution casting method using Propylene Glycol as a plasticizer for packaging applications. The effect of the plasticizer content (10, 15, 20 and 25 wt%) on mechanical properties (tensile strength, young’s modulus and  % of elongation) was investigated. A thermal degradation and phase transition of the prepared WPI was assessed by means of TGA and DSC analysis. The results showed that the tensile strength and young’s modulus decreased and  % of elongation increased with increasing PG content. The ATR-FTIR and SEM were used for structural characterization and morphology of the films, respectively. FTIR studies reveals that the intensity of the bands corresponding to the amide groups increases with increasing PG content tending to increase protein–PG interactions. Further, the glass transition temperature was decreased and the thermal stability of the WPI was found to be increased by plasticization. The overall thermal stability of the films was improved and is attributed to the increase in mobility of the polymer chains.     

The Effect of Nanoclays on the Properties of PLLA-modified Polymers Part 1: Mechanical and Thermal Properties

Organically modified montmorillonite clays were incorporated at a 5% loading level into film grade of poly-L-lactic acid (PLLA) using a variety of masterbatches based on either semi-crystalline or amorphous poly-(lactic acid), as well as biodegradable aromatic aliphatic polyester. The PLLA masterbatches and compounded formulations were prepared using a twin screw compounding extruder, while the films were prepared using a single screw cast film extruder. The thermal and mechanical properties of the films were examined in order to determine the effect of the clay and different carriers on the polymer–clay interactions. In the optimal case, when a PLLA-based masterbatch was used, the tensile modulus increased by 30%, elongation increased by 40%, and the cold crystallization temperature decreased by 15 °C, compared to neat PLLA. The properties improvement of PLLA films containing nano clays demonstrated the possibility to extend the range of biodegradable film applications, especially in the field of packaging.     

Effect of <Emphasis Type="Italic">Moringa oleifera</Emphasis> Pod Husk Fibers on the Properties of Gelatin-Based Biocomposite

The objective of this work is to study the feasibility of reinforcing polymer composites by utilizing the biofibers from the agricultural residue of Moringa oleifera pod husks (MOPH). The chemical and physical properties of the fibers were comprehensively investigated to evaluate their potential as a filler in gelatin-based films. The effect of MOPH fiber concentrations of 0, 5, 10, and 15 wt% on the water vapor permeability (WVP), and mechanical and thermal properties of the gelatin-based films was studied. By incorporation of 10 wt% of the MOPH fibers in gelatin, the highest tensile strength and Young’s modulus, and the lowest WVP properties were obtained. Scanning electron microscopy (SEM) photographs indicated good interfacial adhesion between the fibers and the gelatin matrix. TGA of the biocomposites revealed an improvement of thermal stability. Moreover, under accelerated weathering, the gelatin-MOPH-10% biocomposite degraded more slowly than the gelatin control. These results indicate that the MOPH fibers are a good reinforcing filler and may be useful for biocomposite applications.     

Synthesis and Characterization of Lactic Acid Oligomers: Evaluation of Performance as Poly(Lactic Acid) Plasticizers

The use of fully bio-based and biodegradable materials for massive applications, such as food packaging, is an emerging tendency in polymer research. But the formulations proposed in this way should preserve or even increase the functional properties of conventional polymers, such as transparency, homogeneity, mechanical properties and low migration of their components to foodstuff. This is not always trivial, in particular when brittle biopolymers, such as poly(lactic acid) (PLA), are considered. In this work the formulation of innovative materials based on PLA modified with highly compatible plasticizers, i.e. oligomers of lactic acid (OLAs) is proposed. Three different synthesis conditions for OLAs were tested and the resulting additives were further blended with commercial PLA obtaining transparent and ductile materials, able for films manufacturing. These materials were tested in their structural, thermal and tensile properties and the best formulation among the three materials was selected. OLA with molar mass (M_n) around 1,000 Da is proposed as an innovative and fully compatible and biodegradable plasticizer for PLA, able to replace conventional plasticizers (phthalates, adipates or citrates) currently used for films manufacturing in food packaging applications.     

Mechanical Properties with the Functional Group of Additives for Starch/PVA Blend Film

This paper deals with the mechanical properties and degree of swelling (DS) of starch/PVA blend film with the functional groups i.e., hydroxyl and carboxyl group, of additives. Starch/PVA blend films were prepared by using the mixing process. Glycerol (GL) with 3 hydroxyl group, sorbitol (SO) with 6 hydroxyl group, succinic acid (SA) with 2 carboxyl group, malic acid (MA) with 1 hydroxyl and 2 carboxyl group, tartaric acid (TA) with 2 hydroxyl and 2 carboxyl group and citric acid (CA) with 1 hydroxyl and 3 carboxyl group were used as additives. The results of measured tensile strength (TS) and elongation (%E) verified that both hydroxyl and carboxyl group as a functional groups increased the flexibility and strength of the film. Values of DS for GL-added and SA-added films were low. However, DS values of the films added MA, TA or CA with both hydroxyl and carboxyl group were comparatively high. When the film was dried at low temperature, the properties of the films were evidently improved. The reason is probably because the hydrogen bonding was activated at low temperature.     

A Novel Biodegradable Green Poly(l-Aspartic Acid-Citric Acid) Copolymer for Antimicrobial Applications

Poly (l-aspartic acid-citric acid) green copolymers were developed using thermal polymerization of aspartic acid (ASP) and citric acid (CA) followed by direct bulk melt condensation technique. Antibacterial properties of copolymer of aspartic acid based were investigated as a function of citric acid content. This study is focused on the microorganism inhibition performance of aspartic acid based copolymers. Results showed that inhibition properties increase with increasing citric acid content. Characterization of obtained copolymers was carried out with the help of infrared absorption spectra (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The antibacterial activity of copolymers against bacteria like E-coli, Bacillus and pseudomonas was investigated. The copolymers showed excellent antimicrobial activities against three types of microorganisms. Overall studies indicated that the above copolymers possess a broad wound dressing activity against above three types of bacteria and may be useful as antibacterial agents.     

The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

Effect of Varying Filler Concentration on Zinc Oxide Nanoparticle Embedded Chitosan Films as Potential Food Packaging Material

Prevailing scenario of non-biodegradable food packaging materials worldwide was the motivation for this research. More than half of the packaging materials used today are non-biodegradable and lack one or the other feature that keeps it from being an ideal food packaging material. Based on the current need of food grade packaging materials, the present study illustrates the amelioration of the properties of biodegradable chitosan films with the incorporation of zinc oxide (ZnO) nanoparticles in varying concentration. The ZnO nanoparticles (ZnONPs) used as fillers in the chitosan films were synthesized by supersaturation method. They were characterized using UV–visible spectrophotometry, X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The particles were observed to be around 100–200 nm in size. The chitosan films with varying concentration of ZnONPs were synthesized and characterized using Fourier transform infrared spectroscopy and FE-SEM. The films were studied for their thermal stability, water vapor transmission rate (WVTR) and mechanical properties. The thermal stability, as determined by Thermo Gravimetric Analysis and Differential Scanning Calorimetry increased slightly with increasing percentage of embedded ZnONPs while a substantial decrease in WVTR was observed. Mechanical properties also showed improvements with 77% increment in tensile modulus and 67% increment in tensile strength. The antimicrobial activity of the films was also studied on gram positive bacterium Bacillus subtilis (B. subtilis) and gram negative bacterium Escherichia coli (E. coli) by serial dilution method. A twofold and 1.5-fold increment in the antimicrobial activity was observed for B. subtilis and E. coli, respectively, with increased ZnONPs concentration in the films from 0(w/w) to 2%(w/w). Films thus prepared can prove to be of immense potential in the near future for antimicrobial food packaging applications.     

Biodegradability of Chemically Modified Starch (RS4)/PVA Blend Films: Part 2

Biodegradable films were successfully prepared by using cornstarch (CS), chemically modified starch (RS4), polyvinyl alcohol (PVA), glycerol (GL), and citric acid (CA). The physical properties and biodegradability of the films using CS, RS4, and additives were investigated. The results of the investigation revealed that the RS4-added film was better than the CS-added film in tensile strength (TS), elongation at break (%E), swelling behavior (SB) and solubility (S). Especially, the RS4/PVA blend film with CA as an additive showed physical properties superior to other films. Furthermore, when the film was dried at low temperature, the properties of the films clearly improved because the hydrogen bonding was activated at low temperature. The biodegradation of films was carried out using the enzymatic, microbiological and soil burial test. The enzyme used in this study was amyloglucosidase (AMG), α-amylase (α-AM) and β-amylase (β-AM). At the enzymatic degradation test, the GL-added films had an approximately 60% degradation, while the CA-added films were degraded about 25%. The low degradation value on CA-added film is attributed to low pH of film added CA that deactivated the enzymatic reaction. The microbiological degradation teat was performed by using Bacillus subtilis and Aspergillus niger.     

The Effect of Polymeric Chain Extenders on Physical Properties of Thermoplastic Starch and Polylactic Acid Blends

The effects of a polymeric chain extender on the properties of bioplastic film made from blends of plasticized polylactic acid (p-PLA) and thermoplastic starch (TPS) were studied. Joncryl^? ADR 4370S, a polymeric chain extender, was blended with TPS and p-PLA at a level of 1% (w/w). A co-rotating twin-screw extrusion process was used to prepare films with various ratios of TPS and p-PLA. Mechanical and physical properties of films, including film tensile properties, surface energy, moisture content, hydrophilicity, moisture sorption behaviour and thermal mechanical properties were determined. During extrusion, films enhanced by 1% Joncryl addition demonstrated more desirable and consistent qualities, such as smoother film edge and surface. Addition of Joncryl significantly improved film tensile strength, 0.2% offset yield strength, and elongation, especially evident with the 250% elongation of 70/30 (TPS/p-PLA) film. Total surface energy of films was not significantly influenced by addition of Joncryl. However, the polar contribution to the total surface energy of 70/30 (TPS/p-PLA) film increased after the addition of Joncryl. The study showed that blending TPS with p-PLA transformed TPS film from being highly hydrophilic to highly hydrophobic. On the other hand, addition of Joncryl had limited effects on moisture content, water solubility, glass transition temperature and moisture sorption behaviour of TPS/p-PLA blend films.     

Biopolymers Based Green Composites: Mechanical, Thermal and Physico-chemical Characterization

Natural cellulosic fibers are one of the smartest materials for use as reinforcement in polymers possessing a number of applications. Keeping in mind the immense advantages of the natural fibers, in present work synthesis of natural cellulosic fibers reinforced polymer composites through compression molding technique have been reported. Scanning Electron microscopy (SEM), Thermo gravimetric/Differential thermal/Derivative Thermogravimetry (TGA/DTA/DTG), absorption in different solvents, moisture absorbance, water uptake and chemical resistance measurements were used as characterization techniques for evaluating the different behaviour of cellulosic natural fibers reinforced polymer composites. Effect of fiber loading on mechanical properties like tensile strength, flexural strength, compressive strength and wear resistances has also been determined. Reinforcing of the polymer matrix with natural fibers was done in the form of short fiber. Present work indicates that green composites can be successfully fabricated with useful mechanical properties. These composites may be used in secondary structural applications in automotive, housing etc.     

Life Cycle Analysis of Extruded Films Based on Poly(lactic acid)/Cellulose Nanocrystal/Limonene: A Comparative Study with ATBC Plasticized PLA/OMMT Systems

Life cycle analysis (LCA) of limonene plasticized poly(lactic acid) (PLA) films containing cellulose nanocrystals (CNC) extracted, by acid hydrolysis, from Phormium tenax leaf fibres, was assessed and compared with the results of acetyl tributyl citrate (ATBC) plasticized PLA films, having equivalent mechanical properties, containing organo-modified montmorillonite (OMMT). Eco-Indicator 99 tool has been adopted as the main method for life cycle assessment. Results indicated that, despite CNC are biobased fillers obtained by natural sources, the related chemical extraction leads to a large environmental footprint and a relatively relevant energy expense. LCA characterization of these films demonstrated that the environmental impact of PLA/limonene film reinforced with 1% in weight of CNC (PLA/CNC/limonene) is comparable to the environmental impact of polylactic acid films reinforced with OMMT and plasticized with a petroleum based plasticizer (ATBC) (PLA/OMTT/ATBC). A “cradle to gate” approach has been considered for both the film typologies.     

Characterization of poly(lactic acid) biocomposites filled with chestnut shell waste

The aim of this study was to determine thermal and mechanical properties and applicability of ground chestnut shell waste as a filler for poly(lactic acid) composites. The used amount of filler was ranging from 2.5 to 30 wt%. Spectroscopic analysis of composites and its ingredients was conducted by means of FT-IR method. The mechanical and thermal properties of the composites were determined in the course of static tensile test, Dynstat impact strength test, DMTA analysis, and DSC method. The fractured surface morphology of biocomposites was evaluated by SEM analysis. Incorporation of the filler influenced the overall mechanical properties of the composites characterized by high stiffness and lowered impact resistance. Fabricated composites with different amounts of non-reactive natural waste filler exhibited acceptable mechanical and thermal properties. Therefore, these composites can be used as eco-friendly, biodegradable materials for low-demanding applications.     

Physical Properties of Chemically Modified Starch(RS4)/PVA Blend Films—Part 1

In this paper, we report on the physical properties of films that have been synthesized by using native corn starch (NS) and chemically modified starch (RS4). NS or RS4/PVA blend films were synthesized by using the mixing process and the casting method. Glycerol (GL), sorbitol (SO), and citric acid (CA) were used as additives. The chemically modified starch (RS4) was synthesized by using sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) as a crosslinker. Then, the RS4 thus synthesized was confirmed by using the pancreatin-gravimetric method, swelling power and an X-ray diffractometer (XRD). Tensile strength (TS), elongation (%E), swelling behavior (SB), and solubility (S) of the films were measured. The result of the measurements indicated the RS4-added film was better than the NS-added film. Especially, the RS4/PVA blend film with CA as an additive showed the physical properties superior to other films.     

Films Made by Blending Poly(ε-Caprolactone) with Starch and Flour from Sagu Rhizome Grown at the Venezuelan Amazons

Starch-based composite films have been proposed as food packaging. In this context, the study of non-conventional starch sources (sagu, Canna edulis Kerr) has worldwide special attention, because these materials can impart different properties as carbohydrate polymers. A thorough study of the matrices used (sagu starch and flour) was carried out. In the same way, thermoplastic starch (TPS)/PCL blend and thermoplastic flour (TFS)/PCL blend were obtained by melt mixing followed by compression moulding containing glycerol as plasticizer. In this study, chemical composition of the matrices and their properties were related with the properties of the developed films. Moisture content, water solubility, X-ray diffraction, thermogravimetric analysis and mechanical and microstructural properties were evaluated in the films. Taking into account the results, the sagu flour has great potential as starchy source for food packaging applications. However, concretely the flour had lower compatibility with the PCL compared to the starch/PCL blend.     

Properties of Starch/PVA Blend Films Containing Citric Acid as Additive

Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature.     

Effect of Biaxial Stretching on Thermal Properties, Shrinkage and Mechanical Properties of Poly (Lactic Acid) Films

This study produced poly (lactic acid) sheets using a biaxial stretching process, to investigate the effects of biaxial stretching on thermal properties, crystallinity, shrinkage and mechanical properties of PLA films. The results of differential scanning calorimetry show that the glass temperature peak of PLA films, which weakened after stretching. The cold crystallization peak of PLA films nearly disappeared at stretch ratios of 4 × 4 with a stretching rate above 50 %/s. The orientation and strain crystallization of PLA films were suppressed at stretching temperatures of approximately 100–110 °C. The shrinkage of PLA decreased proportionally to the stretch rate and inversely proportional to the stretching temperature, suggesting that the internal stresses frozen in the amorphous phase were an indication of a decrease in the crystallinity of the films, implying that PLA films would be best suited to low-shrinkage applications. The stress–strain of the PLA films increased considerably following the biaxial stretching process. In addition, PLA films exposed to hot water treatment show a slight decrease in stress values, probably attributable to a relaxation of the molecules, which have undergone orientation but failed to crystallize.     

Chitosan/Hydrophilic Plasticizer-Based Films: Preparation,Physicochemical and Antimicrobial Properties

The addition of plasticizers to biopolymer films is a good method for improving their physicochemical properties. The aim of this study was to evaluate the effect of chitosan (CHI) blended with two hydrophilic plasticizers glycerol (GLY) and sorbitol (SOR), at two concentrations (20 and 40 wt%) on their mechanical, thermal, barrier, structural, morphological and antimicrobial properties. The chitosan was prepared through the alkaline deacetylation of chitin obtained from fermented lactic from shrimp heads. The obtained chitosan had a degree of deacetylation (DA) of 84 ± 2.7 and a molecular weight of 136 kDa, which indicated that a good film had formed. The films composed of CHI and GLY (20 wt%) exhibited the best mechanical properties compared to the neat chitosan film. The percentage of elongation at break increase to over 700 % in the films that contained 40 % GLY, and these films also exhibited the highest values for the water vapor transmission rate (WVTR) of 79.6 ± 1.9 g m² h^?1 and a yellow color (b _o  = 17.9 ± 2.0) compared to the neat chitosan films (b _o  = 8.8 ± 0.8). For the structural properties, the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analyses revealed an interaction in the acetamide group and changes in the crystallinity of plasticized films. The scanning electron micrographs revealed that all formulations of the chitosan films were smooth, and that they did not contain aggregations, pores or microphase separation. The thermal analysis using differential scanning calorimetry (DSC) revealed a glass transition temperature (Tg) of 130 °C for neat chitosan film, but the addition of SOR or GLY elicited a decrease in the temperature of the peak (120 °C). In addition, the antimicrobial activity of the chitosan films was evaluated against Listeria monocytogenes, and reached a reduction of 2 log after 24 h. The plasticizer concentration of 20 % GLY is sufficient for obtaining flexible chitosan films with good mechanical properties, and it could serve as an alternative as a packaging material to reduce environmental problems associated with synthetic packaging films.