Development and characterization of composite edible films based on sodium alginate and pectin

The objective of this study was to characterize physical properties including thickness, colour, water vapour sorption kinetics and isotherms, water vapour permeability, tensile strength, elongation at break, and microstructure of composite films prepared by casting sodium alginate and low methoxy pectin at proportions of: 100–0%, 75–25%, 50–50%, 25–75%, and 0–100%. Combination of both polysaccharides gave continuous, homogenous and transparent films. All of analyzed films reached their state of equilibrium within the 24 h of adsorption time. Water sorption isotherms for all films had a sigmoidal shape and were not influenced by the film composition. Sorption kinetics and isotherms indicated hydrophilic character of investigated films. Statistically significant (p < 0.001) correlations were found between colour, water vapour permeability, tensile strength, elongation at break, and chemical composition (alginate and pectin) of composite films. A different internal arrangement was observed as a function of film composition.     

鲢鱼皮明胶-海藻酸钠复合膜的制备与性能

鲢鱼皮明胶膜因具有安全性高和来源丰富等优点受到广泛关注。然而鲢鱼皮明胶膜的力学性能和阻隔性能 较差,若作为食品包装膜将会受到限制。为了改善鲢鱼皮明胶膜的性能,将海藻酸钠与鲢鱼皮明胶共混制成复合 膜。结果发现,制成的复合膜外观透亮,有阻隔紫外线和油脂的性质;当添加体积分数为20%的海藻酸钠时,复合 膜的水溶性和水蒸气透过率达到最小,抗拉强度达到最大。说明复合膜的阻隔性能和力学性能都优于鲢鱼皮明胶 膜。对膜的傅里叶变换红外光谱图和X射线衍射图进行分析,表明鲢鱼皮明胶和海藻酸钠存在较强的相互作用,这 可能是复合膜性能发生变化的主要原因。     

蛋清蛋白/苹果多酚提高多糖基可食性包装薄膜性能及在腰果贮藏保鲜中的应用

海藻酸钠（sodium alginate,SA）、κ-卡拉胶（κ-carrageenan,κ-C）具有天然无毒、成膜性好的特点,常被用于制备可食用多糖基包装膜。但多糖薄膜具有亲水性强、机械性能差、抗氧化活性低等缺陷。本实验以SA、κ-C为复合多糖成膜基质,以乳酸钙为交联剂,并添加蛋清蛋白粉（egg white powder,EWP）增强多糖薄膜综合包装性能,添加苹果多酚（apple polyphenol,AP）作为抗氧化剂赋予薄膜抗氧化功能。通过傅里叶变换红外光谱、X射线衍射、扫描电子显微镜、紫外吸收光谱等方法分析各组分基团间相互作用,并对腰果仁进行包装贮藏保鲜实验。结果表明：本研究制备的多糖基可食用包装薄膜具有较好的综合包装性能和突出的抗氧化性能。与SA/κ-C薄膜相比,Ca2＋的交联使可食性薄膜的机械性能、阻隔性能显著提升。在最优添加量下,添加EWP使薄膜断裂延伸率由7.99%提高至20.81%,水蒸气渗透率降低了28.84%,氧气渗透率降低了27.07%;加入AP后,可食性薄膜抗张强度由18.58 MPa提升到30.23 MPa,水蒸气渗透率降低了42.35%,氧气渗透率降低了34.13%,同时薄膜阻光性能显著提升。此外,AP/EWP/SA/κ-C可食性薄膜包装降低了腰果仁贮藏期间的水分活度、水分质量分数、过氧化值和酸价,能有效抑制腰果仁的氧化酸败。结论：研究可为多糖/蛋白质基可食性复合包装薄膜的制备及应用提供参考。     

酸解淀粉/PBAT复合膜的制备及其性能研究

为了提高淀粉基复合膜的力学性能和阻水性能,以酸解淀粉和聚己二酸-对苯二甲酸丁二醇酯（PBAT）为主要成膜基材,通过挤出吹塑法制备了酸解淀粉/PBAT复合膜,研究了淀粉/PBAT比例对复合膜结构、力学性能和阻隔性能等的影响。结果表明,随着PBAT含量的增加,淀粉/PBAT共混物的流动性增强,模量与复合黏度降低,淀粉与PBAT之间的氢键作用减弱。添加PBAT可显著提高淀粉膜的力学性能和阻隔性能,复合膜纵向最大拉伸强度和断裂伸长率分别为7.86 MPa和532.67%,最低水蒸气和氧气透过系数分别为3.74×10?11 g?m?1?s?1?Pa?1和5.77×10?15 cm2?s?1?Pa?1。     

羧甲基纤维素强化胶原纤维膜的制备及其性能分析

基于静电相互作用（离子键、范德华力）的蛋白质-多糖聚合现象成为改良可食膜的重要手段。本实验以酸溶胀胶原纤维（正电性）为基料,研究带负电性的羧甲基纤维素（carboxymethyl cellulose,CMC）对胶原纤维膜性能的影响。结果表明：当CMC添加量（以胶原纤维质量计,下同）过多（大于10%）,成膜液发生絮凝甚至分层现象而不能成膜;随着CMC添加量（范围为0%～5.0%）的增加,成膜液ζ-电势显著下降,pH值无明显变化,复合膜表面越来越粗糙,膜厚度增加,透光率显著降低（P＜0.05）;复合膜拉伸强度和杨氏模量随CMC添加量增加而显著增加（P＜0.05）,而断裂延伸率显著降低（P＜0.05）;当CMC添加量达5.0%时,复合膜的水蒸气透过率达到（32.41±0.86）g/（m·s·Pa）,阻氧性与膜溶胀动力学性能显著提高（P＜0.05）;此外,热稳定性分析表明添加CMC能够提高复合膜热稳定性。由此可知,CMC能够通过静电相互作用促进与胶原纤维的结合,提高胶原纤维膜相关机械强度和阻隔性能,从而为可食膜性能提升提供了一种可行手段。     

Influence of the homogenization conditions and lipid self-association on properties of sodium caseinate based films containing oleic and stearic acids

The effect of the homogenization conditions of the film-forming emulsions and lipid self-association on the physical properties of sodium caseinate films containing oleic and stearic acids was studied. For this purpose, different film-forming emulsions were prepared by using different homogenization methods and were characterized as to particle size distribution and rheological properties. Likewise, mechanical, structural and optical properties and water vapour permeability (WVP) of the obtained films were also determined. While films containing stearic acid showed a laminar-like structure, oleic acid was more homogeneously dispersed in the film matrix. These differences in structure make the stearic acid films less flexible, showing more surface roughness and less gloss and transparency than films containing oleic acid. The film microstructure also affects the WVP. In this sense, for oleic acid films, water barrier efficiency increased when homogenization conditions were more intense, whereas for films containing stearic acid, the opposite effect was observed. This different behavior was attributed to the different kind of lipid self-association in the aqueous media, protein interactions and their impact on the final film microstructure.     

海藻酸钠对鱼皮明胶膜理化特性的影响

采用罗非鱼皮明胶与海藻酸钠混合制备可食性复合膜,研究海藻酸钠含量对复合膜理化性质的影响。结果显示：单一罗非鱼皮明胶具有良好的成膜能力,但是机械性能差,将海藻酸钠添加到明胶膜中得到的复合膜抗拉强度和断裂伸长率有明显改善,海藻酸钠添加量在40%时,抗拉强度达最大值6.6?MPa,相对于纯明胶膜（5.5?MPa）和纯海藻酸钠膜（4.6?MPa）分别增加20%和43%,断裂伸长率也在此时达到最大值120%,比纯明胶膜（64%）和纯海藻酸钠膜（88%）分别增加87.5%和26.7%。海藻酸钠水溶性和吸湿率分别高达100%和48.7%,经共混后复合膜的水溶性降低至55%以下,吸湿率介于25%～40%之间,有较大的改善。流变学特性和X射线衍射分析结果表明：明胶和海藻酸钠具有良好的相容性,二者共混可制得性质稳定的复合膜,海藻酸钠与明胶的复合膜液为非牛顿流体,黏度和增稠能力较单一明胶膜有所增加。     

Mechanical and water vapor barrier properties of tapioca starch/decolorized hsian-tsao leaf gum films in the presence of plasticizer

The objectives of this research were to examine the mechanical and water vapor barrier properties of the starch/decolorized hsian-tsao leaf gum (dHG) films as a function of dHG and glycerol concentration. Edible film-forming solutions were prepared by mixing tapioca starch with dHG at different starch/dHG ratios to make a total solid content of 2%. In total, 15–40% glycerol was then added based on the dry film matter. Starch/dHG films were obtained by casting. It was found that the puncture strength, tensile strength, and modulus as well as the inverse of relaxation coefficient of starch/dHG films pronouncedly increased with increasing dHG, accompanied with a decreasing tendency in puncture deformation and tensile strain at break. Such results implied that starch interacted with dHG synergistically, resulting in the formation of a new network to improve the mechanical properties of tapioca starch/dHG films. Mechanical strengths of starch/dHG films decreased and water vapor permeability (WVP) at 75% RH increased with increasing glycerol concentration. However, the plasticizing effect of glycerol became less significant at high dHG concentration, particularly for the puncture deformation and tensile strain at break of the films. Water sorption isotherm results indicated that significant water sorption would only occur at high water activity (about 0.75), and generally became more pronounced with increasing glycerol and dHG concentration, but to a lesser extent for the latter. Dynamic mechanical analysis revealed that the major glass transition of starch/dHG films occurred at about −50 °C.     

Influence of alginate emulsion-based films structure on its barrier properties and on the protection of microencapsulated aroma compound

In recent years the use of natural polymers coming from renewable sources has greatly increased due to the over-solid packaging waste and dwindling petroleum reserves. Biopolymer films, which contain both lipid and polysaccharide ingredients to form complex packaging enable us to obtain edible films with good mechanical and water barrier properties as emulsified alginate edible films. Moreover, these can be considered to encapsulate active molecules as flavours. The aim of this work is to better understand the influence of the composition and the structure of the film matrix on its barrier properties and thus on its capacity to protect encapsulated active substances. Granulometry, Differential Scanning Calorimetry (DSC) and Microscopy (MEB) characterizations of films with or without flavour and/or fat showed that the encapsulated n-hexanal compound modifies the film structure because of interactions with the alginate matrix. This interaction affects the studied barrier properties, oxygen permeability, aroma compound permeability, liquid aroma permeability and surface properties, of emulsified alginate films. This study brings new understanding on the role of emulsion-based edible films as a matrix and on its ability to protect encapsulated aroma compounds and on its barrier properties.     

Natamycin release from alginate/pectin films for food packaging applications

Single and composite films based on alginate and pectin containing natamycin as active agent were prepared and the release behavior in water and the diffusion coefficients were evaluated. The influence of natamycin on physical attributes of the films was also investigated. Addition of natamycin promoted an increase in soluble matter in water, in the water vapor permeability and in the opacity and a decreased in tensile strength when compared to films without the added anti-microbial agent. The natamycin mass released by immersion of the film in water fitted well to Fick’s second law diffusional model, with effective diffusivity values ranging from 3.2 × 10⁻⁹ (single pectin films) to 9.2 × 10⁻¹² cm²/s (single alginate films). The values of the diffusional exponents ranged between 0.5 and 1.0, suggesting that the transport process had non-Fickian (anomalous) characteristics. The single alginate films exhibit more suitable attributes for application in packaging than the single pectin and the composite films.     

海藻酸钠/微晶纤维素复合壁材的性能及对精油微胶囊缓释性的影响

将微晶纤维素与海藻酸钠混合,形成复合壁材用于制备精油微胶囊。通过探讨微晶纤维素的添加对壁材溶液流变性以及壁材膜机械性能、透油性、吸湿性和透水性的影响,研究海藻酸钠/微晶纤维素复合壁材对柠檬精油微胶囊包埋效率及精油释放速率的影响。结果表明,复合溶液表观黏度随微晶纤维素含量的增加而增加,随温度的升高而逐渐下降,且都比海藻酸钠的表观黏度高。红外光谱结果表明海藻酸钠和微晶纤维素相容性很好,通过氢键形成复合体系。微晶纤维素较大程度增强壁材复合膜的机械性能,膜的透油性、吸湿性和透水性随微晶纤维素的增加而降低。4%微晶纤维素含量的复合壁材对柠檬精油微胶囊包埋效率比未添加的效率提高了9.2%,并且微晶纤维素的添加能有效延缓微胶囊精油在高温和高湿环境下的释放。     

静态超高压处理对抗菌复合蛋白薄膜的改性研究

本研究以乳清分离蛋白和酪蛋白酸钠为成膜基材,甘油为增塑剂,山梨酸钾为抗菌剂制备复合蛋白成膜溶液,在其流延成薄膜之前对成膜溶液分组并进行了静态超高压处理:压力分别为200、300、400 MPa,处理时间分别为5、10、20、30 min,未经超高压处理的为对照组。通过对13组薄膜样品的机械性能、光学性能、水溶性、微观结构、阻隔性能等参数的分析,结果表明,超高压处理的薄膜表面更光滑和均匀,有较少的孔洞。超高压处理对薄膜的机械性能、阻隔性能均有显著性(p<0.05)影响,超高压压力300 MPa,处理20 min后,薄膜抗拉强度达到最大值4.86 MPa;C₄组薄膜的水蒸气透过系数降低到1.177×10-9 g·cm/cm2·s·Pa;超高压压力200 MPa,处理10 min后氧气渗透系数降低到0.93×10-9 cm3·cm/cm2·s·cmHg。超高压处理对组B₁、C₁、D₄水溶性均有显著性(p<0.05)影响,能够使薄膜水溶性降低。不同超高压处理后的薄膜可适应不同包装食品的货架期要求。     

蛋壳膜酶解肽对大豆蛋白包装膜抑菌、抗氧化性能的影响

蛋白膜具有良好的机械性能,是一种环境友好的可食性包装材料,但其抑菌、抗氧化性能等包装活性较差,限制其在某些易腐食品包装领域的广泛应用.本研究以大豆分离蛋白(soy protein isolate,SPI)为成膜基质,加入不同添加量的蛋壳膜(eggshell membrane,ESM)酶解肽制备复合膜,以机械性能、阻隔性...     

新型共混膜的制备及在烟草薄片中的应用研究

将多糖(藻酸丙二醇酯(PGA)、果胶、卡拉胶、芦荟多糖)以共干燥和直接加入两种方式对大豆分离蛋白(SPI)/脂类膜共混改性,研究多糖对膜水蒸气透过系数(WVP)及机械性能的改善作用。结果表明,共干燥法加入4种多糖,都能明显降低SPI/脂类/多糖膜的WVP;抗拉强度(TS)随着多糖的加入显著提高,而且共干燥法加入PGA还能显著提高膜的伸长率(E%);SPI/脂类膜与共干燥法制备的SPI/脂类/多糖膜阻氧性能没有显著区别。共干燥法共混改性效果优于直接加入法,且PGA对膜改性作用最为显著。多糖改性对膜微观结构的影响表明SPI、脂类、多糖形成的可食性膜微观结构决定了膜的阻隔性能和机械性能。其对烟草薄片的机械加工性能作用与前述基本一致。     

Water barrier and physical properties of starch/decolorized hsian-tsao leaf gum films: Impact of surfactant lamination

The moisture barrier and physical properties of bilayer films prepared by lamination of starch/decolorized hsian-tsao leaf gum (dHG) and surfactant layers were investigated. It was found that the water vapor permeability (WVP) of tapioca starch/dHG film (1.31 × 10^?10 g/m s Pa) pronouncedly decreased by the aid of a surfactant layer lamination (1.36–5.25 × 10^?12 g/m s Pa). The WVP of bilayer film increased with increasing the concentration of starch/dHG in the surfactant layer, but was not significantly influenced when it was thickened. The sorption isotherms of both monolayer and bilayer films made from starch/dHG showed typical behavior of water-vapor-sensitive hydrophilic biopolymers. However, the equilibrium moisture content of the monolayer film was significantly higher than that of bilayer films when water activity (a_w) reaches 0.33. Both the tensile and puncture force of starch/dHG films did not vary significantly by laminating a surfactant layer, indicating the mechanical strength of surfactant layer is relatively weak, and this surfactant layer mainly served as a barrier for moisture. When compared to emulsion-based starch/dHG films with surfactant, the surfactant laminated starch/dHG films showed higher water barrier property, mechanical strength, and transparency.     

Fabrication and physicochemical characterization of HPMC films with commercial plant extract: Influence of light and film composition

Betacyanins used as natural red color (NRC) are known as antioxidants. The present paper was focused on their effect on physicochemical properties of hydroxypropyl methylcellulose (HPMC) films. All the films were evaluated for their photo-aging stability on optical, mechanical, barrier, thermal and structural properties. Both, tensile strength and Young's modules of NRC composite films decreased, while elongation significantly increased compared to control films. Dynamic vapor sorption data fitted by Guggenheim–Anderson–de Boer (GAB) model showed lower values of sorption energy for NRC composite films. NRC films showed an initial decrease in oxygen permeability that was more decreased after 20 days of photo-aging. Inversely, a significant increase in water vapor permeability of films by increasing NRC was observed. The films composed of 4% NRC (v/v) showed the highest WVP and lowest oxygen permeability. HPMC films transparency decreased with NRC contents.     

Physicochemical,Water Vapor Barrier and Mechanical Properties of Corn Starch and Chitosan Composite Films

Biodegradable flexible films were developed from corn starch (CS) and chitosan (CH); their microstructure, mechanical and barrier properties were evaluated. Chitosan and starch blend filmogenic suspensions showed a pseudoplastic behavior, similar to that of chitosan solutions. Smooth surfaces, homogeneous and compact film structures were observed from microstructure studies using scanning electron microscopy (SEM). The addition of glycerol reduced film opacity and increased film solubility of both CS and composite CS‐CH films. Water vapor permeability values of composite CS‐CH films plasticized with glycerol ranged between 3.76 and 4.54× 10⁻¹¹ g s⁻¹ m⁻¹ Pa⁻¹, lower than those of the single component films. CS‐CH films were resistant and their flexibility increased with glycerol addition. Tensile strength values of CS‐CH films were comparable to those of low‐density and high‐density polyethylenes but lower than that obtained for cellophane, however, composite biodegradable films showed lower elongation at break values than the synthetic commercial ones. In conclusion, CS‐CH films can be described as biofilms with a homogeneous matrix, stable structure and interesting water barrier and mechanical properties, with great possibilities of utilization, and with the advantage of biodegradability.     

Trout skin gelatin-based edible film development

Edible biopolymer films were developed from gelatin extracted from trout skin (TSG) using thermal protein denaturation conditions and plasticizer (glycerol) concentration as variables. The amino acid composition of the TSG, elastic modulus, viscous modulus, and the viscosity of film-forming solutions, and tensile properties, water vapor permeability, solubility in water, and color of TSG-based films were determined. A 6.8% (w/w, wet basis) trout skin-extracted gelatin solution containing 9, 17, or 23% (w/w, dry basis) glycerol was heated at 80, 90, or 100 °C for 30, 45, or 60 min to prepare a film-forming solution. TSG can be characterized as a gelatin containing high contents of methionine and aspartic acid. The gelation temperature of the film-forming solution was 7 °C and the solution was subjected to heating to form a stable matrix for a film. Increased heating time of the film-forming solution reduced the film solubility (P < 0.05). Heating at 90 °C for 30 min was suggested as the requirement for film formation. As the concentration of glycerol in the film increased, film strength and moisture barrier properties decreased, while film stretchability increased (P < 0.05). Trout skin by-products can be used as a natural protein source for fabricating biopolymer films stable at ambient conditions with certain physical and moisture barrier properties by controlling thermal treatment conditions and glycerol concentrations. Practical Application: The fishing industry produces a significant amount of waste, including fish skin, due to fish processing. Trout skin waste has potential value as a protein source that can be used to form biopolymer edible films for packaging low and intermediate water activity food products, and thus may have practical applications in the food industry, which could be one way to cut waste disposal in the trout processing industry.     

Physical, Morphological, and Barrier Properties of Edible Casein Films with Wax Applications

ABSTRACT:  The overall research objective was to investigate the effects of wax application to casein films on the physical, morphological, mechanical, and water barrier properties of the films. Casein films were prepared by cross-linking with zein hydrolysate using transglutaminase. Wax was either incorporated into the film-forming solution or coated onto the casein films. The physical, morphological, and mechanical properties of wax-incorporated or wax-coated casein films were characterized. The wax-casein films exhibited darker color than casein film, and the film thickness ranged from 0.2 to 0.4 mm. Wax application significantly decreased the tensile strengths and Young's Modulus of casein films. The wax-incorporated films exhibited a greater reduction in tensile strength and Young's Modulus than the wax-coated films. The microstructures of wax-casein films were relatively smooth and uniform when observed under a scanning electron microscope. Wax applications significantly decreased the water vapor permeability (WVP) of the casein films, and the wax-coated casein films exhibited a greater decrease in WVP than the wax-incorporated films.     

Blend films of pectin and bitter vetch (Vicia ervilia) proteins: Properties and effect of transglutaminase

Hydrocolloid solutions were prepared by blending pectins and Vicia ervilia seed proteins at complexation pH and edible films were obtained by casting the solutions both in the absence and presence of microbial transglutaminase. Protein/pectin films exhibited a tensile strength double than the one observed with films containing only proteins, with an increase of about 3-fold observed in the presence of enzyme. Also the elongation at break resulted higher in the films containing transglutaminase, leading to conclude that films are more extensible mostly when both pectins and enzyme occur in the film forming solutions. A direct correlation between the improved film mechanical properties and the negative increase of zeta-potential of the originating film forming solutions was recorded. Conversely, gas permeability of protein/pectin films markedly decreased and transglutaminase addition determined a further enhancement of their barrier properties. These findings, supported by morphological analyses, suggest that the improved film functional features depend on their more compact structure due to crosslinked bitter vetch proteins grafted with pectin.Industrial relevanceThe innovative packaging is becoming an important focus as food industries increasingly endeavor to reduce the environmental impact of their products. Biodegradable and/or edible materials made from renewable sources are interesting alternatives to produce ecofriendly food coatings being able to substitute petrochemical films and to reduce plastic wastes. Development of blended polysaccharide/protein-based biomaterials is an attractive option in the attempt of tuning biodegradable films endowed with tailored properties. In this study an improvement of bitter vetch protein edible films by pectin grafting and transglutaminase treatment is investigated.