Pullulan Films Research Articles

Effect of Gelatin Addition on Properties of Pullulan Films

The gelatin was added into pullulan films to improve their performances and lower their cost. The gelatin addition raised the tensile strength of the gelatin-pullulan composite films, and reduced the oxygen permeability. The cost of composite films was reduced comparing to that of the pullulan films. Moreover, the molecular interaction of the composite film was evaluated. The interactions of gelatin and pullulan in the composite films were detected, such as (1) formation of 2 glycosylated proteins; (2) improvement of β-sheet content; (3) formation of the interchain hydrogen bond and a semicrystalline region. Therefore, the molecular interaction was the main reason for the performance improvement of the composite films.

Pullulan–nanofibrillated cellulose composite films with improved thermal and mechanical properties

Abstract Novel bionanocomposite films with improved thermal and mechanical properties, were prepared by casting water-based suspensions of pullulan and nanofibrillated cellulose. The effect of the addition of glycerol, as a plasticizer, on the properties of the materials was also evaluated. The ensuing materials were characterized in terms of morphology, thermal stability, crystalline structure and mechanical properties. All bionanocomposites were very homogeneous, translucent and showed considerable improvements in thermal stability (increments of up to 20 °C in the degradation temperature) and mechanical properties (increments of up to 5500% and 8000% in the Young’s modulus and tensile strength, respectively, for films plasticized with glycerol) when compared to the unfilled pullulan films. Additionally, these novel bionanocomposite could be labeled as sustainable materials since they were prepared entirely from renewable resources and through a green approach.

Sustainable nanocomposite films based on bacterial cellulose and pullulan

Bionanocomposites with improved properties based on two microbial polysaccharides, pullulan and bacterial cellulose, were prepared and characterized. The novel materials were obtained through a simple green approach by casting water-based suspensions of pullulan and bacterial cellulose and characterized by TGA, RDX, tensile assays, SEM and AFM. The effect of the addition of glycerol, as a plasticizer, on the properties of the materials was also evaluated. All bionanocomposites showed considerable improvement in thermal stability and mechanical properties, compared to the unfilled pullulan films, evidenced by the significant increase in the degradation temperature (up to 40 °C) and on both Young’s modulus and tensile strength (increments of up to 100 and 50%, for films without glycerol and up to 8,000 and 7,000% for those plasticized with glycerol). Moreover, these bionanocomposite films are highly translucent and could be labelled as sustainable materials since they were prepared entirely from renewable resources and could find applications in areas as organic electronics, dry food packaging and in the biomedical field.

Preparation and Properties of Pullulan Composite Films

In the paper, preparation and properties of pullulan composite films were studied. Several kinds of materials (glass, iron, steel, propene polymer and polyvinyl chloride plates) were chosen for preparing films. The results showed that the steel plate was the most suitable material for preparing film. The tensile strength of pullulan film was significantly reduced when the drying temperature was higher than 50°C. The time of dissolution observably decreased, whereas water vapor permeability increased with increasing drying temperature. Pullulan film has higher tensile strength, better water barrier properties, shorter solubilization time and lower elongation at break than those of hydroxypropylmethylcellulose film, respectively. The composite film (Pullulan and hydroxypropylmethylcellulose) with weight ratio (1/2) has higher tensile strength, better water barrier properties, longer solubilization time than those of other ratios. Difference properties of films could be obtained in different weight ratio (Pullulan and hydroxypropylmethylcellulose).

Grewia Gum 1: Some Mechanical and Swelling Properties of Compact and Film

Purpose: To study the mechanical and dynamic swelling properties of grewia gum, evaluate its compression behaviour and determine the effect of drying methods on its properties.Methods: Compacts (500 mg) of both freeze-dried and air-dried grewia gum were separately prepared by compression on a potassium bromide (KBr) press at different pressures and subjected to Heckel analysis. Swelling studies were performed using 200 mg compacts of the gum (freeze-dried or air-dried) compressed on a KBr press. The mechanical properties of the films of the gum prepared by casting 1 % dispersions of the gum were evaluated using Hounsfield tensiometer. The mechanical properties of grewia gum films were compared with films of pullulan and guar gum which were similarly prepared. The effect of temperature on the water uptake of the compacts was studied and the data subjected toSchott’s analysis. Results: Drying conditions had no effect on the yield pressure of the gum compacts as both air-dried and freeze-dried fractions had a yield pressure of 322.6 MPa. The plots based on Schott’s equation for the grewia gum samples showed that both samples (freeze-dried and air-dried) exhibited long swelling times. Grewia gum film had a tensile strength of 19.22±3.61 MPa which was similar to that of pullulan films (p > 0.05). It had an elastic modulus of 2.13±0.12 N/mm2 which was significantly lower (p < 0.05) than those of pullulan and guar gum with elastic moduli of 3.33±0.00 and 2.86±0.00 N/mm2, respectively.Conclusion: The type of drying method used does not have any effect on the degree of plasticity of grewia gum compacts. Grewia gum obtained by either drying method exhibited extended swelling duration. Matrix tablet formulations of the gum will likely swell slowly and promote sustained release of drug.Keywords: Grewia gum compact, Films, Heckel analysis, Swelling behaviour

Properties of pullulan-based blend films as affected by alginate content and relative humidity.

Pullulan-sodium alginate blend films were prepared and characterized as a function of water activity (aw). At low aw, the incorporation of alginate into pullulan film increased the tensile strength and elastic modulus, but decreased the elongation at break of the composite films; the opposite trends were observed at elevated aw. Above 0.43 aw, water exerted a typical plasticization effect upon the biopolymer blends. As aw increased from 0.23 to 0.43, an anti-plasticization effect was observed as tensile strength and elastic modulus increased. The glass transition temperature of all samples decreased substantially as aw increased from 0.23 to 0.84 due to the plasticization effect of water. Within this aw range, one transition temperature was observed for all film specimens. The stretching vibration band of O-H was investigated using attenuated total reflection Fourier transform infrared spectroscopy to identify the various species of water interacting with the polysaccharide films.

Effects of ingredient composition on optical and mechanical properties of pullulan film for food-packaging applications

In the present research, the effects of pullulan (Pul), glycerin (Gly), xanthan gum (Xa) and locust bean (Lb) concentrations on pullulan film properties were investigated using a Central Composite Rotatable Design. Optimal ingredient combination was determined and antimicrobial activity of films combined with sakacin A was confirmed against Listeria monocytogenes. Using predictive models, contour plots and the characteristics of commercial LDPE films as constraints, the following combination within the optimal region was selected: Pul 100 g/l, Gly 10 g/l, Xa 1 g/l and Lb 1 g/l. Statistical analysis demonstrated that Pul and Gly significantly influenced the properties of pullulan films. Strong interactions were observed between Pul-Gly and Xa-Gly. When sakacin A was added to the film mixture, no significant influence on films optical properties was reported, while an increase in flexibility was observed. Results obtained indicate the potential application of pullulan film developed in this study as an effective antimicrobial biopolymer in food-packaging systems.

Antibacterial activity of pullulan films containing thymol

ABSTRACTThymol displays strong activity against microorganisms that are of interest in clinical field and in food industry. Pullulan can form homogeneous films, which is an important property for its use as a coating material in the food industry. The present study determining the effect of thymol incorporated into a pullulan film against selected bacteria. The final content of thymol in the dried films ranged from 2.5 mg/cm2 to 52.9 mg/cm2. The structure of the surface and cross‐section of the films were observed under a scanning electron microscope. The fruits were coated with a pullulan film, with thymol incorporated in the concentrations of 1.2, 1.5 and 3.0% and were evaluated for appearance and aroma. The pullulan films with thymol content ranging from 26.5 mg/cm2 to 52.9 mg/cm2 expressed strong inhibitory activity against the tested bacteria, compared with the pullulan films containing lesser concentration of thymol. The surface of the coated fruits was found to be shiny as compared with the non‐coated fruits. Though the characteristic aroma of thymol was detectable it did evoke any undesirable sensory changes. Pullulan films containing thymol, which were effective against the tested bacteria, can be applied to extend the shelf life of packaged food products. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Effect of rice wax on water vapour permeability and sorption properties of edible pullulan films

Edible films were prepared using various ratios of pullulan and rice wax. Freestanding composite films were obtained with up to 46.4% rice wax. Water vapour barrier properties of the pullulan film were improved with increased addition of rice wax. Moisture sorption isotherms were also studied to examine the impact of rice wax on the water sorption characteristics of the film. The Brunauer–Emmet–Teller (BET) and Guggenheim–Anderson–de Boer (GAB) sorption models were tested to fit the experimental data. The models gave a good fit up to the water activity (aw) of 0.55 for BET and a full range of aw from 0.12 to 0.95 for GAB (R2⩾0.98). Changes in the sorption parameters, particularly such as the decrease in monolayer moisture content (Mo), reflect the trend of reduced hydration capacity with increased addition of rice wax, providing useful information on water activity conditions to achieve stability for the composite films.

Preparation of Fast Dissolving Films for Oral Dosage from Natural Polysaccharides.

Fast-dissolving films (FDFs) were prepared from natural polysaccharides, such as pullulan, without heating, controlling the pH, or adding other materials. The release profiles of model drugs from the films were investigated. In the absence of a drug, the casting method and subsequent evaporation of the solvent resulted in the polysaccharide forming a circular film. The presence of drugs (both their type and concentration) affected film formation. The thickness of the film was controllable by adjusting the concentration of the polysaccharide, and regular unevenness was observed on the surface of 2% pullulan film. All films prepared with polysaccharides readily swelled in dissolution medium, released the incorporated compound, and subsequently disintegrated. The release of dexamethasone from the films was complete after 15 min, although this release rate was slightly slower than that of pilocarpine or lidocaine. Therefore, FDFs prepared from polysaccharides could be promising candidates as oral dosage forms containing drugs, and would be expected to show drug dissolution in the oral cavity.

SAKACIN A‐CONTAINING PULLULAN FILM: AN ACTIVE PACKAGING SYSTEM TO CONTROL EPIDEMIC CLONES OF LISTERIA MONOCYTOGENES IN READY‐TO‐EAT FOODS

ABSTRACT The effectiveness of sakacin A, a bacteriocin produced by Lactobacillus sakei DSMZ 6333, was evaluated against epidemic clones of Listeria monocytogenes isolated from foodborne outbreaks; sakacin A activity was determined in ready‐to‐eat (RTE) foods, and a biopolymer was identified to deliver the bacteriocin onto a RTE food. Sakacin A demonstrated antimicrobial activity against epidemic clones of L. monocytogenes in food slurries. When sakacin A (50 mg/mL) was applied directly to experimentally inoculated turkey breast, populations of the most sensitive epidemic clone were reduced more than 2 log10 cfu/g after 3 weeks at 4C. Sakacin A‐containing (1 mg/cm2) pullulan films demonstrated antimicrobial activity in vitro. When experimentally inoculated surfaces of turkey breast were treated with these pullulan films, L. monocytogenes populations were reduced 3 log10 cfu/g after 3 weeks under refrigerated storage. These results demonstrate the possibility of using sakacin A‐containing‐pullulan film to inhibit or reduce L. monocytogenes on the surface of a RTE food.PRACTICAL APPLICATIONSIncreased use of synthetic packaging films has led to ecological problems due to their nonbiodegradability. Consumers are demanding that food packaging materials be made of biobased materials, and to be easily biodegradable and recyclable. The incorporation and/or slow release of antimicrobial agents in packaging materials may provide a means of extending the bacterial lag phase, reducing microorganism growth rate and extending the shelf life of foods. Bacteriocins are compounds that can be used as a means of biopreservation. In this study, we demonstrated the effectiveness of sakacin A‐containing pullulan films to control Listeria monocytogenes growth and the applicability of active pullulan films as a means of delivering a bacteriocin directly to a food surface. Pullulan films require less antimicrobial, demonstrate longer antimicrobial activity and allow for controlled migration of the molecule from film to the food matrix, as compared with the direct addition of sakacin A to ready‐to‐eat meat products.

Viability of Porcine Embryos after Vitrification Using Water-soluble Pullulan Films

The efficiency of a porcine embryo vitrification method that uses water-soluble films of pullulan, a naturally-occurring polysaccharide polymer, was compared with two other types of vitrification methods using different devices and solutions for vitrification and warming. Blastocysts collected in vivo and vitrified by the conventional straw (ST), Cryotop((R)) (MVC) or pullulan film vitrification (PFV) methods were stored in liquid nitrogen for a certain period of time, after which the cryoprotective agents were removed by stepwise dilution. Fresh embryos were used as controls for the non-vitrification group. The vitrified-warmed embryos were incubated in TCM199 with 0.1 mM beta-mercaptoethanol and 20% fetal bovine serum for 24 h at 38.5 C in humidified air with 5% CO(2) to evaluate their viability. The survival rate of embryos in the ST group (48.3%) was significantly lower than that of those in the MVC (70.7%), PFV (79.0%) and non-vitrification (94.4%) groups. The oxygen consumption rate after vitrification was significantly lower than that before vitrification in the ST group, but was not significantly different in the MVC and PFV groups. Both the oxygen consumption rates of embryos after warming and the live cell numbers in the ST group were lower than those in the MVC group, while they did not differ significantly between the PFV and MVC groups. There was a correlation between the oxygen consumption rate and the number of live cells in vitrified embryos after warming. Our results demonstrated that in vivo-derived porcine embryos could be vitrified using pullulan films.

천연물 유래 항균물질을 포함한 가식성 Pullulan 필름의 충치유발균에 대한 항균효과

This study was focused on the development of anticariogenic edible films using pullulan containing grapefruit seed extract (GFSE), polylysine or propolis. According to the result of antimicrobial activity (disc diffusion method) of GFSE, polylysine and propolis against Streptococcus mutans, antimicrobial pullulan film was produced by adding grapefruit seed extract. The optimum combination of pullulan and sorbitol (plasticizer) was 10~15% (w/v) and 40~50% of pullulan (w/w), respectively. Minimum concentration of grapefruit seed extract for growth inhibition of Str. mutans was 50 ppm in medium. Formulation of antimicrobial pullulan films containing grape seed extract was established and these results evidently showed potential for commercial application.

Evaluation of relationship between molecular behaviour and mechanical strength of pullulan films

This study aimed to investigate the relationship between the physical properties and molecular behaviour of pullulan films. To study its thermal behaviour, we obtained a pullulan film by the solvent cast method and analysed it by differential scanning calorimetry (DSC), thermogravimetry analysis (TG), thermo-mechanical analysis (TMA) and FT-IR spectroscopy. The pullulan film contracted with an increase in temperature, and the film contraction depended on the decrease in water content in the film. The FT-IR spectra of a pullulan film was used as a calibration model set to establish such a model to predict the film contraction and water content by principal component regression (PCR) analysis. The film contraction and water content could be predicted using a calibration model obtained by PCR. The molecular behaviour of pullulan films due to film contraction and decreased water content were demonstrated by analysing the regression vector consisting of PC1 and PC2.

Preparation and properties of pullulan–alginate–carboxymethylcellulose blend films

Abstract Pullulan, alginate, and carboxymethylcellulose (CMC) films were solvent cast from aqueous polymer solution. At 55% RH and 20 °C, their tensile strength and elongation at break were 67 MPa and 11%, 49 MPa and 5.2%, and 45 MPa and 5.8%, respectively. Pullulan films had lower water vapor permeability than alginate and CMC films (4.4 × 10−7, 9.7 × 10−7, and 1.3 × 10−6 g m/Pa h m2, respectively), but dissolved in water quicker than alginate and CMC films. By incorporating alginate and CMC into pullulan, water barrier and mechanical properties were weakened significantly. Blending pullulan with alginate or CMC up to about 17–33% (w/w total polymer) reduced film solubilization time in water. The addition of glycerol further reduced tensile strength, increased elongation at break, weakened water barrier properties, but enhanced solubilization in water. FTIR results indicated that blending pullulan with alginate and CMC resulted in weaker hydrogen bonds acting on –OH groups compared to the pure pullulan.

Matrix assisted pulsed laser evaporation of pullulan tailor-made biomaterial thin films for controlled drug delivery systems

We report the first successful deposition of cinnamate-pullulan polysaccharide thin films by Matrix Assisted Pulsed Laser Evaporation (MAPLE). Thin film depositions were performed in vacuum using a KrF* excimer laser source (λ = 248 nm, τ ≈ 20 ns) operated at a repetition rate of 10 Hz. The dependence on incident laser fluence of the induced surface morphology is studied. We demonstrated by Raman spectroscopy that our MAPLE-deposited cinnamate-pullulan thin films are composed of starting materials preserving their chemical structures, with no impurities.

Physical properties of starch nanocrystal-reinforced pullulan films

Nanocomposite materials were prepared using sorbitol-plasticized pullulan as the amorphous matrix and an aqueous suspension of starch nanocrystals (prepared by submitting native granules from waxy maize starch to acid hydrolysis at 35 °C) as the reinforcing phase. Wide-angle X-ray diffraction analysis showed an increase of the crystallinity of the composite biopolymer films with increasing of starch nanocrystal content. The water absorption isotherms and kinetics as well as the water barrier properties of nanocomposite films filled with 0–40% (w/w) starch nanocrystals (starch nanocrystals/pullulan + sorbitol) were investigated. The water uptake of pullulan–starch nanocomposites decreased with increasing filler content whereas water vapor permeability (measured at 25 °C and 53/100 relative humidity (RH) gradient) remained constant up to 20% (w/w) and, then decreased significantly with further addition of nanocrystals. The thermo-mechanical behaviour of nanocomposite films was also investigated by means of dynamic mechanical thermal analysis (DMTA) and large deformation mechanical tests (tensile mode). The glass transition temperature ( T g) shifted towards higher temperatures with increasing amount of nanocrystals, which can be attributed to a restriction of the mobility of pullulan chains due to the establishment of strong interactions not only between starch nanocrystals but also between the filler and the matrix. Moreover, the addition of nanocrystals caused strong enhancement of the Young modulus and the tensile strength, but led to a drastic decrease of the strain at break in samples conditioned at different environments (from 43% to 75% RH).

Water sorption and thermo-mechanical properties of water/sorbitol-plasticized composite biopolymer films: Caseinate–pullulan bilayers and blends

The moisture sorption and thermo-mechanical behavior of pullulan, sodium caseinate and their blend and bilayer films (weight polymer ratio 1:1) were studied. All plain and composite films containing the same level of sorbitol showed very similar equilibrium water content. Incompatibility between both polymers was assumed, since separate tan δ peaks corresponding to those of the two pure components, were observed in the DMTA thermal traces of their blends containing 25% w/w (dry solids) sorbitol. The thermo-mechanical properties of polyol-free blends and bilayers were governed by pullulan, as their behavior was too similar to that of pullulan alone. The plasticizing effect of water was evident in all samples, with the pullulan, blend and bilayer films exhibiting greater glass transition temperature ( T g ) depression than the plain sodium caseinate films at similar moisture content levels. This differentiation was attributed to structural variation between the two polymers. Sorbitol addition decreased the T g of both polymers at water contents up to 10% w/w; however, at higher hydration levels sodium caseinate exhibited an increase in T g in contrast to pullulan, which showed a continuous decline. The apparent activation energy E a of the primary relaxation ( α-relaxation) decreased with increasing moisture and sorbitol content. In all sorbitol-plasticized films, a low-temperature relaxation (tan δ peak) observed in the region of T g of sorbitol, shifted to lower temperature with increasing moisture content; the intensity of this transition increased with increasing sorbitol content and the corresponding E a values were similar to those of a primary relaxation. The low-temperature transition might originate from a coupling of β-relaxation of the polymer and the α-motions of sorbitol. The fragility parameter, m, was calculated for all systems and allowed their characterization as relatively strong materials according to Angell's classification; the fragility decreased with increasing water content. The time–temperature superposition principle, using the Williams–Landel–Ferry equation, applied successfully to plain polymer films as well as to blends and bilayers, assuming that the C 1 and C 2 constants do not take their universal values, but are optimized for each system separately.

121VITRIFICATION OF MOUSE MORULAE BY A NEW METHOD: PULLULAN FILM-STRAW VITRIFICATION

Recent technical improvements have resulted in higher cryosurvival of oocytes and embryos of various species. However, almost all methods require thawing and washing the embryos under microscopic observation and, therefore, cannot be conveniently used for large animal ET in the field. The purpose of the present work was to develop a new embryo cryopreservation method using a water-soluble film made of pullulan (Hayashibara, Okayama, Japan) that might, in the future, be readily adaptable to field conditions. Morula-stage mouse embryos were collected from superovulated ICR donors 72h after hCG injection. Embryos were first exposed to 10% DMSO+10% ethylene glycol (EG) in DPBS+20% FCS (mPBS) for 2min, and then equilibrated for 30s in a vitrification solution composed of 20% DMSO+20% EG+0.6M sucrose in mPBS. In the pullulan film-straw vitrification method, the embryos were loaded onto the pullulan film (20μm thick, 5mm long and 1mm wide) and were directly plunged into LN2. The pullulan film was inserted into a pre-frozen 0.25mL plastic straw (&amp;lt;−150°C) containing 0.15mL mPBS and sealed with a plastic screw cap. For thawing, the medium in the straw was rapidly warmed in 37°C water while the pullulan film remained frozen by placing the top of the straw in contact with a cold iron block (&amp;lt;−150°C). As soon as the medium thawed, the pullulan film was immersed in the medium by a rapid downward swinging of the straw. Five min later, embryos were recovered from the straw and washed for 2min in mPBS, for 2min in 0.1% BSA-PBS and for 2min in KSOM sequentially, and then cultured at 37°C in 5% CO2 for 38h. Noncryopreserved embryos and embryos cryopreserved by the cryoloop method (Lane et al., 1999 Nat. Biotech. 17, 1234) served as controls. Data were analyzed by χ2 test and Student’s t-test. Results are shown in Table 1. There are no significant differences (P&amp;gt;0.05) in either developmental abilities or cell numbers between vitrified and non-vitrified embryos. This study demonstrates that mouse morulae can be successfully vitrified and thawed by the PFSV method. This method may eventually be applied to bovine ET under field conditions. Table 1 Development of mouse morulae in culture following vitrification by the PFSV method

Electrical properties of composite cyanoethylated pullulan film

Electrical properties of composite cyanoethylated pullulan film