Effects of lipids on mechanical and moisture barrier properties of edible gellan film

Beeswax or a 1:1 blend of stearic–palmitic acids (S–P) were incorporated into gellan films through emulsification to form gellan/lipid composite films. The films, containing 0–25% lipid (dry film basis) were examined for mechanical properties, water vapor permeability (WVP) and opacity. Addition of the lipids to gellan films significantly improved the WVP (P<0.05), but lowered the mechanical properties and caused the films to become opaque. Beeswax was more effective than S–P acids in reducing the WVP, and films with beeswax showed better mechanical properties overall than those with S–P acids. The tensile properties of gellan films containing 14.3% beeswax were evaluated as a function of water activity (a_w) of the film. Increasing the a_w decreased the tensile strength (TS) and elastic modulus but tensile elongation was not affected. The extent of the decreases in TS for the composite film was less pronounced than that for a similar film without lipids, suggesting that lipids help to alleviate moisture sensitivity of gellan films.     

Effect of the presence of glycerol and Tween 20 on the chemical and physical properties of films based on chitosan with different degree of deacetylation

Chitosans with two different deacetylation degree (DD) (60.9% and 96%) were used to elaborate edible films. The influence of the degree of deacetylation and the presence of glycerol and Tween 20 in the formulation on the surface tension of the film forming solutions as well as on the chemical structure, optical and mechanical properties and water vapor permeability (WVP) of the resulting films were studied.IR spectra showed no significant differences on the chemical structures of chitosan of the different films. However, X-ray diffraction analysis indicated that the use of chitosan with higher DD and the use of glycerol as additive resulted in higher crystallinity. Films made of chitosan with the lower DD (60.9%) were found to have higher tensile strength (TS) and elongation (E) in a tensile test. Degree of deacetylation did not have any effect on WVP. The presence of glycerol resulted in less resistant, more elastic and more permeable films.The presence of Tween 20 improved the wettability of film solutions and affected significatively mechanical, optical and barrier properties of the films. A positive interaction between glycerol and Tween 20 was observed for WVP.     

Development and characterization of cassava starch and soy protein concentrate based edible films

The sensory attributes, mechanical, water vapour permeability (WVP) and solubility properties of cassava starch and soy protein concentrate (SPC)‐based edible films of varying levels of glycerol were studied. Addition of SPC and glycerol up to 30% and 20%, respectively, reduced stickiness and improved colour and appearance of the films. Tensile strength (TS), elastic modulus (EM) and elongation at break (EAB) of films increased, while film solubility (FS) and WVP decreased with SPC and glycerol up to 50% and 20% level, respectively, ranging from 20.33 to 26.94 MPa (TS), 41.33 to 72.76 MPa (EM), 7.90 to 12.28 MPa (EAB), 15.07 to 31.90% (FS) and 2.62 to 4.13 g H₂O mm m^?2 day kPa (WVP). The TS, EAB and WVP were higher for the biofilms than for low‐density polyethylene and cellophane films.     

Improved water vapor barrier of whey protein films by addition of an acetylated monoglyceride

This study aimed to determine to what extent the water-vapor barrier of whey protein isolate (WPI) films could be improved by adding a lipid and make laminate and emulsion films. The laminate whey protein–lipid film decreased the water vapor permeability (WVP) 70 times compared with the WPI film. The WVP of the emulsion films was half the value of the WPI film and was not affected by changes in lipid concentration, whereas an increased homogenization led to a slight reduction in WVP. The mechanical properties showed that the lipid functioned as an apparent plasticizer by enhancing the fracture properties of the emulsion films. This effect increased with homogenization. The maximum strain at break was 117% compared with 50% for the less-homogenized emulsion films and 20% for the pure WPI films. Phase-separated emulsion films were produced with a concentration gradient of fat through the films, but pure bilayer films were not formed.     

The Evaluation of Mechanical,Thermal, Optical and Microstructural Properties of Edible Films with Solid Lipid Nanoparticles-Xanthan Gum Stored at Different Temperatures and Relative Humidities

Solid lipid nanoparticles (SLN) were obtained using the hot homogenization method and incorporated into a xanthan gum matrix (XG) to prepare edible films. The effects of SLN content (60, 65, 70, and 75 g/L) on the mechanical, color, thermal and microstructural properties, and water vapor permeability (WVP) were studied. The SLN film-forming systems remained stable for 7 weeks. Particle size was in the range of 222–257 nm. The mechanical properties of the films improved significantly when the SLN were introduced into the polymeric network to provide greater strength and flexibility with elongation at breaking of 2–9 %, affected by temperature (4–25 °C), SLN concentration (60–75 g/L), and relative humidity (60–90 %). WVP was lower when edible films based on XG were incorporated with SLN at values of 0.50–0.70 g m-2 h-1 kPa^?1. The distribution of the SLN in the XG matrix was observed under scanning electron microscopy and showed changes in the arrangement as a function of SLN concentration. This explains the positive effect on the properties of the film of SLN-XG at 60 and 65 g/L. Total color difference (ΔE) increased with SLN content at values of 3.5–14. Thermal analysis showed that higher SLN content increased the melting temperature, while the plasticizer reduced it.     

Combined effects of lemon essential oil and surfactants on physical and structural properties of chitosan films

The aim of this research was to evaluate the effects of lemon essential oil (LO, at 0.5%, 1%, 2% v/v film‐forming solutions) and surfactants (Tween 80 and Span 80 at 0.1% v/v film‐forming solutions) on physical, optical and structural properties of chitosan (CH) films. The films were formed by casting method. Results showed that the incorporation of LO provoked a decrease in water content, water vapour permeability (WVP) and mechanical properties. Less transparency and higher total colour difference were observed in CH–LO composite films. The addition of surfactants significantly increased WVP and solubility in water of CH–LO films. The film containing Tween 80 showed lower mechanical strength and higher transparency. The morphology was different depending on the LO contents and surfactant types used. Tween 80 improved the stability of LO in the film, whereas Span 80 promoted the movement of oil droplets to the film surface.     

Permeability and Mechanical Properties of Cellulose-Based Edible Films

Factors affecting barrier properties [oxygen permeability (OP) and water vapor permeability (WVP)] and mechanical properties [tensile strength (TS) and elongation (E)] were investigated for methyl cellulose (MC) and hydroxypropyl cellulose (HPC) films. OP, WVP and TS of MC and HPC films increased as the molecular weight (MW) of the cellulose increased. E of MC films increased as MW increased, but E of HPC films was highest for the intermediate MW of 370,000. OP, WVP and TS of MC films were not a function of thickness, but E slowly increased as film thickness increased. OP and WVP of HPC films were not relatable to film thickness, but TS and E of HPC films slowly increased as film thickness increased. TS decreased and E increased for both film types as concentration of plasticizers was increased. Plasticizers enhanced or retarded OP and WVP of cellulose-based films, depending on their concentrations.     

Combined effect of plasticizers and surfactants on the physical properties of starch based edible films

Films made of potato starch were developed and glycerol as plasticizer and Tween 20, Span 80, and soy lecithin as surfactants were included in the formulation. Films were characterized with respect to water vapor permeability (WVP) and mechanical properties. The wettability of the film solutions was quantified by measuring their surface tension.The incorporation of plasticizers resulted in more flexible and manageable films and higher WVP. At low concentration, Tween 20 was the surfactant that reduced surface tension the most, while at high concentration it was lecithin. In the absence of glycerol, surfactants had a significant effect on mechanical properties, but they did not modify significantly WVP of the films. It was observed a synergistic behavior between the plasticizer and the surfactants. Films with glycerol and high level of any of the surfactants behaved as films with larger amount of plasticizer (with lower tensile strength, higher elongation, and higher WVP). Tween 20 was the surfactant that showed the most intense synergistic effect with glycerol.     

Formation and characterization of shellac-hydroxypropyl methylcellulose composite films

Shellac-hydroxypropyl methylcellulose composite films (Sh-HPMC-CFs) were produced and the effects of emulsifier and shellac concentration on the Sh-HPMC-CFs were investigated. Two emulsifiers, stearic acid (SA) and lauric acid (LA), with three ratios of shellac to emulsifier (100:1, 20:1, and 10:1) were tested to select the best ratio of shellac to emulsifier before testing the effect of shellac concentration. When compared to pure HPMC film, the WVP was decreased by 6 and 11% in the Sh-HPMC-CFs containing shellac to LA (ShLA) ratios of 100:1 and 20:1, respectively. However, all the ShSA-HPMC-CFs had higher WVP than the pure HPMC film. In relation to mechanical properties, the ShLA(20:1)-HPMC-CF had the lowest reduction in TS when compared to a pure HPMC film. Therefore, ShLA(20:1) was selected for further characterization. Surface morphology, cross sectional image, thermal stability, WVP, and mechanical properties of the Sh-HPMC-CFs were also measured at varying shellac concentrations (0.1, 0.5, 1.0, and 1.5%). The 0.1 and 0.5% Sh-HPMC-CFs had good distribution of shellac in the film structure while the 1.0 and 1.5% Sh-HPMC-CFs exhibited some agglomeration of shellac. The 0.1 and 0.5% Sh-HPMC-CFs had better moisture barrier than the pure HPMC film. All Sh-HPMC-CFs had better thermal stability than the pure HPMC film and its thermal stability increased as shellac concentration increased.     

Mechanical and barrier properties of biodegradable soy protein isolate-based films coated with polylactic acid

Polylactic acid (PLA)-coated soy protein isolate (SPI) films were prepared by dipping SPI film into PLA solution. The effects of coating on improvements in mechanical and water barrier properties of the film were tested by measuring selected film properties such as tensile strength (TS), elongation at break (E), water vapor permeability (WVP), and water solubility (WS). TS of SPI films increased from 2.8±0.3 up to 17.4±2.1 MPa, depending on the PLA concentration of the coating solution, without sacrificing the film's extensibility. In contrast, the extensibility of SPI film coated with solution containing more than 2 g PLA/100 ml solvent, increased. WVP of PLA-coated SPI films decreased from 20 to 60 fold, depending on the concentration of PLA coating solution. Water resistance of SPI films was greatly improved as demonstrated by the dramatic decrease in WS for PLA-coated films. The improvement in water barrier properties was mainly attributed to the hydrophobicity of PLA.     

Properties and Stability of Protein-based Films from Red Tilapia (Oreochromis niloticus) Protein Isolate Incorporated with Antioxidant during Storage

Film from fish protein isolate (FPI) from red tilapia (Oreochromis niloticus) muscle prepared at pH 3 and incorporated with 100 ppm Trolox (FPIT film) was prepared and characterized in comparison with film prepared from unwashed mince film (UWM film) during storage of 40 days at room temperature (28–32°C). FPIT film had higher tensile strength (TS) and elongation at break (EAB) but lower water vapor permeability (WVP) than UWM film (p?<?0.05). During the storage, FPIT film had much lower thiobarbituric acid reactive substances value than UWM film. Furthermore, FPIT was more transparent and had no yellow discoloration, as evidenced by no change in b* and ΔE* values during the storage of 40 days. Both UWM and FPIT films were stabilized mainly by hydrogen bond, followed by hydrophobic interaction, disulfide bond, and nondisulfide covalent bond. Fourier transforms infrared spectra indicated that FPIT film contained the lower amount of lipids with the lower amplitude of amide B band, compared with UWM film. Higher degradation temperature (Td) was observed in FPIT film, indicating a greater protein–protein interaction in film matrix. FPIT film had smoother surface and cross-section than UWM film. After 40 days of storage, both films had the increase in TS and Td but lower EAB, WVP, and protein solubility. This was more pronounced in UWM film and was associated with the formation of nondisulfide covalent bond in the film network, most likely mediated by the interaction between protein and lipid oxidation products via Maillard reaction. Thus, film from FPI incorporated with antioxidant had the improved mechanical and physical properties without yellow discoloration.     

Effect of Molecular Weight,Acid, and Plasticizer on the Physicochemical and Antibacterial Properties of β‐Chitosan Based Films

Abstract: Effects of chitosan molecular weight (1815 and 366 kDa), type of acid (1% acetic, formic, and propionic acid, or 0.5% lactic acid) and plasticizer (0, 25% glycerol or sorbital w/w chitosan) on the mechanical, water barrier, and antibacterial properties of β‐chitosan films were investigated. Tensile strength (TS) of high molecular weight (Hw) films was 53% higher than that of low molecular weight (Lw) ones, acetate, and propionate films had the highest TS (43 and 40 MPa) among tested acids, and plasticizer‐reduced film TS 34%. Film elongation at break (EL) was higher in Hw films than in Lw ones, in which formate and acetate films were the highest (9% and 8%, respectively), and plasticizer increased the film EL 128%. Molecular weight of chitosan did not influence water vapor permeability (WVP) of the films. Acetate and propionate films had lower WVP than other acid types of films, and plasticizer increased film WVP about 35%. No difference was found between glycerol and sorbitol films in terms of film mechanical and water barrier properties. Lw β‐chitosan films showed significant antibacterial activity against E. coli and L. innocua. This study demonstrated that β‐chitosan films are compatible to α‐chitosan films in physicochemical properties and antibacterial activity, yet with simple sample preparation. Practical Application: β‐chitosan based edible films at molecular weight of about 300 kDa showed great antibacterial activity against Gram‐positive and Gram‐negative bacteria. The films have similar mechanical and water barrier properties to α‐chitosan based films at the similar molecular weight, but simple sample preparation procedures and more attractive color. The release of active chitosan fragment from the film matrix acts as an antibacterial agent, making β‐chitosan films suitable as intelligent food wraps or coatings for a wide range of food products to control moisture loss and prevent surface bacterial growth.     

Effect of glycerol on the physicochemical properties of films based on legume protein concentrates: A comparative study

The overall goal of this research was to examine the mechanical, water vapor barrier properties and opacity of films prepared using legume protein concentrates (faba bean, pea, lupin, lentil, and soy) as a function of glycerol concentration (50, 75, or 100% [wt/wt]—relative to the protein weight). Overall, tensile strength (TS) decreased with increasing glycerol concentration, whereas tensile elongation (TE) and water vapor permeability (WVP) increased with increasing glycerol concentration. Film opacity was independent of glycerol concentration. The effect of protein‐type varied considerably depending on the functional property of the film being measured; TS was greatest with faba bean and lowest with lupin, whereas TE was highest for pea, and lowest for soy. Lentil protein films had considerably higher WVP, at the 100% glycerol concentration, as compared to the other protein concentrates. Findings from this study indicate that legume protein concentrates are capable of forming biodegradable, edible films. Overall, pea protein concentrate films showed the most promise for application in terms of strength, elongation, and moisture barrier properties.     

Properties of sericin–glucomannan composite films

Sericin is a natural silk protein which is removed from silk in a process called degumming. Thus, finding a use for the extracted sericin as a biopolymer film will create added value which will benefit both the economy and society. It was found that extracted sericin could not form stand-alone films. Therefore, glucomannan was incorporated with or without glycerol to form a flexible film. Sericin and glucomannan ratio (S:G) affected film properties. Increasing sericin content (S:G = 2:1) slightly reduced film water vapour permeability (WVP) without adding glycerol (Gly). This indicated that sericin provided film flexibility without increasing film WVP. As expected, increasing glycerol content increased film WVP as well as decreased tensile strength and elastic modulus but increased dramatically % elongation. It is interesting that adding beeswax to form a composite film did not improve film water vapour barrier. Thus, sericin-based film properties are dependent on components used to form film and can tailor to form the desired film flexibility and minimise permeability of films for application.     

Effects of plasticizers and nano-clay content on the physical properties of chicken feather protein composite films

To prepare chicken feather protein (CFP)/nano-clay composite films and to evaluate the effects of various plasticizers and nano-clay concentrations on the mechanical properties of the films, CFP composite films with various concentrations of Cloisite Na⁺ were prepared, and their physical properties such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were investigated. Optimal CFP films were formed with 5 g of CFP, 0.5 g of glycerol, and 1.5 g of sorbitol in 100 mL of film-forming solution; the TS, E, and WVP of the film were 4.74 MPa, 10.08%, and 3.11 × 10⁻⁹ g m/m² s Pa, respectively. After the nano-clay was incorporated into the CFP film-forming solution, scanning electron microscopy and X-ray diffraction studies were conducted to examine the structural characteristics of the CFP/nano-clay composite films. The incorporation of nano-clay improved the physical properties of the CFP films. The TS of the CFP/nano-clay composite film containing 7% Cloisite Na⁺ increased by 1.21 MPa, and the WVP of the composite film decreased by 1.15 × 10⁻⁹ g m/m² s Pa compared to the CFP film. Therefore, these results suggest that CFP composite films can be prepared with improved mechanical property by the addition of nano-clay and used as a food packaging material in the food industry.     

低温储藏条件对大豆分离蛋白膜理化特性的影响

以大豆分离蛋白为原料制得可食性膜,研究在不同低温储藏条件下其功能特性,包括机械性能和阻隔性能的变化。结果显示:随冷藏温度的升高,其功能特性变化较为缓慢。而随冻藏温度的降低,断裂延伸率下降尤为明显,抗拉强度和脂质阻隔能力变化趋势次之,水蒸气透过率升高缓慢。冷藏时间与断裂延伸率呈显著正相关(p<0.05)。冷藏时间与水蒸气透过率和油脂渗透系数均呈极显著正相关(p<0.01)。冻藏时间与水蒸气透过率和油脂渗透系数呈显著正相关(p<0.05)和极显著正相关(p<0.01)。     

Effects of various plasticizers and nanoclays on the mechanical properties of red algae film

To manufacture red algae (RA) film, we used various plasticizers such as glycerol, sorbitol, sucrose, fructose, and polypropylene glycol (PPG), and then determined the mechanical properties of the RA films. The tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of the films containing various plasticizers ranged between 0.43 to 9.10 MPa, 10.93% to 47.17%, and 1.28 to 1.42 ng m/m2sPa, respectively. RA films containing fructose as a plasticizer had the best mechanical properties of all the films evaluated. Incorporation of nanoclay (Cloisite Na+ and 30B) improved the mechanical properties of the films. RA film with 3% Cloisite Na+ had a TS of 10.89, while RA film with 30B had a TS of 10.85 MPa; these films also had better E and WVP values than the other RA films evaluated. These results suggest that RA/nanoclay composite films are suitable for use as food packaging materials. PRACTICAL APPLICATION: Edible RE/nanoclay composite films prepared in the present investigation can be applied in food packaging.     

Preparation and characterization of agar/clay nanocomposite films: the effect of clay type

Abstract: Agar‐based nanocomposite films with different types of nanoclays, such as Cloisite Na⁺, Cloisite 30B, and Cloisite 20A, were prepared using a solvent casting method, and their tensile, water vapor barrier, and antimicrobial properties were tested. Tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of control agar film were 29.7 ± 1.7 MPa, 45.3 ± 9.6%, and (2.22 ± 0.19) × 10^?9 g·m/m²·s·Pa, respectively. All the film properties tested, including transmittance, tensile properties, WVP, and X‐ray diffraction patterns, indicated that Cloisite Na⁺ was the most compatible with agar matrix. TS of the nanocomposite films prepared with 5% Cloisite Na⁺ increased by 18%, while WVP of the nanocomposite films decreased by 24% through nanoclay compounding. Among the agar/clay nanocomposite films tested, only agar/Cloisite 30B nanocomposite film showed a bacteriostatic function against Listeria monocytogenes.     

Migration analysis,antioxidant, and mechanical characterization of polypropylene-based active food packaging films loaded with BHA,BHT, and TBHQ

Polypropylene (PP) based active composite films were prepared by adding butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylated hydroquinone (TBHQ) antioxidants using the extrusion molding process. All concentrations of BHT, 2% to 3% BHA, and 3% TBHQ significantly increased the tensile strength (TS) of the composite films compared with control films. Increasing antioxidant concentration decreased TS values for BHT films, whereas an opposite trend was observed for BHA and TBHQ films. BHA at < 2%, BHT at > 2%, and TBHQ at all added concentrations significantly reduced elongation at break (E_b) of the composite films compared to control films. Water vapor permeability (WVP) of 1% BHT film was not significantly different from control. However, other antioxidants especially at increased concentrations significantly increased WVP values. TBHQ films with 300% to 662% increase had the highest WVP and BHT films with 5% to 81% increase had the lowest WVP among composite films. All three antioxidants had a negative effect on the transparency of the films; however the effect of BHA at higher concentrations was greater. The antioxidants did not change the color attributes of the films. Films containing all antioxidants showed 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, which increased with increase in their concentration, especially for those containing 3 wt.% BHT and TBHQ. Overall, incorporating BHA and BHT into a PP matrix improved mechanical, barrier, antioxidant properties, and film appearance and consequently were proposed for the development of antioxidant active PP films. TBHQ film is not recommended for food packaging because of its weak mechanical properties (lower E_b and TS values, higher WVP, and greater migration).     

环境湿度对植物蛋白膜的影响研究

研究了环境湿度对小麦蛋白膜、大豆蛋白膜以及小麦-大豆复合膜机械性能、通透性等的影响。结果表明,由于蛋白腹为亲水性膜,受环境湿度的影响,其水分含量、分子间作用力有所不同,从而导致蛋白膜的机械性能、透湿性和吸湿率也随之发生变化。膜的阻止水蒸汽渗透的能力下降,吸湿率降低,透氧率呈上升趋势。