Effect of the incorporation of antioxidants on physicochemical and antioxidant properties of wheat starch–chitosan films

Blend edible films were prepared from wheat starch (WS) and chitosan (CH) with glycerol as plasticizer. Four active ingredients (antioxidants) were added, namely basil essential oil, thyme essential oil, citric acid and α-tocopherol. The starch:antioxidant mass ratio was 1:0.1. Prior to characterisation, the films were conditioned at 25 °C–53%RH as to their structural, mechanical, optical and barrier properties. The antioxidant capacity of the active ingredients was determined by means of a spectrophotometric method. The incorporation of antioxidants led to a heterogeneous film microstructure, mainly in those containing α-tocopherol, which affected the surface roughness. Yellowness was induced in films when α-tocopherol was added and no notable colour changes were observed in the other cases, although all the antioxidants increased the transparency of the films. Despite of the fact that the mechanical properties were barely affected by the incorporation of antioxidants, citric acid promoted an increase in the elastic modulus but a decrease in film stretchability. The water vapour barrier properties of the films were only slightly improved when citric acid and α-tocopherol were added, whereas the oxygen barrier properties were significantly improved in all cases. The greatest antioxidant capacity of the films was reported for films containing α-tocopherol, which exhibited the highest antioxidant power.     

Physical and Antimicrobial Properties of Compression-Molded Cassava Starch-Chitosan Films for Meat Preservation

Cassava starch-chitosan films were obtained by melt bending and compression molding, using glycerol and polyethylene glycol as plasticizers. Both the starch/chitosan and the polymer/plasticizer ratios were varied in order to analyze their effect on the physical properties of the films. Additionally, the antimicrobial activity of 70:30 polymer:plasticizer films was tested in cold-stored pork meat slices as affected by chitosan content. All film components were thermally stable up to 200 °C, which guaranteed their thermostability during film processing. Starch and chitosan had limited miscibility by melt blending, which resulted in heterogeneous film microstructure. Polyethylene glycol partially crystallized in the films, to a greater extent as the chitosan ratio increased, which limited its plasticizing effect. The films with the highest plasticizer ratio were more permeable to water vapor, less rigid, and less resistant to break. The variation in the chitosan content did not have a significant effect on water vapor permeability. As the chitosan proportion increased, the films became less stretchable, more rigid, and more resistant to break, with a more saturated yellowish color. The incorporation of the highest amount of chitosan in the films led to the reduction in coliforms and total aerobic counts of cold-stored pork meat slices, thus extending their shelf-life.     

高直链玉米淀粉-壳聚糖复合膜透气透水性能研究

本文以高直链玉米淀粉(HACS)和壳聚糖(CS)为基本材料,甘油为增塑剂,甲基纤维素(MC)为增强剂制备可食性复合膜,研究了高直链玉米淀粉与壳聚糖的配比、甘油的添加量以及甲基纤维素的添加量对复合膜的透气透水性能的影响.结果表明,HACS:CS为2:1时,膜的CO2透过量和O2透过量最低,水蒸气透过量(WVT)也处于较低...     

Preparation and characterization of glycerol plasticized (high-amylose) starch–chitosan films

The chitosan–starch (high amylose) blend film (1;1), via microfluidization, was prepared by casting with different glycerol concentration (0%, 2.5%, 5% and 10%). The films were characterized for their mechanical, thermal and morphological properties. The addition of glycerol at 5% (w/w) and higher concentrations resulted in decrease in tensile strength, increase in elongation at break due to plasticization. The well-known antiplasticization was observed in the polymer films with 2.5% of glycerol. The addition of glycerol promoted the interactions among chitosan, starch and glycerol through hydrogen bonding as reflected on the shifting of main peaks of the glycerol-free film to higher wavenumbers as shown by FTIR spectra. The decrease in intensity of glycerol-related peaks in starch–chitosan–glycerol films in both ¹H NMR and ¹³C NMR spectra proved the strong interactions (decrease in glycerol mobility) occurring among starch, chitosan and glycerol in glycerol-plasticized films.     

不同塑化剂对柠檬酸淀粉酯成膜性能的影响

以甘油、乙二醇、山梨醇和壳聚糖为塑化剂,机械活化柠檬酸淀粉酯为原料,以断裂伸长率为评价指标,通过SEM、FT-IR、TGA和接触角的分析,探讨不同塑化剂对淀粉酯成膜性能的影响。结果表明,不同塑化剂对淀粉酯的影响不同。不同塑化剂对淀粉酯膜的断裂伸长率影响为甘油>山梨醇>乙二醇>壳聚糖>原淀粉。添加塑化剂能使淀粉酯更好地成膜。SEM分析表明,以甘油和壳聚糖为塑化剂的淀粉酯膜具有更多网状结构,表面透气性好;以乙二醇和山梨醇为塑化剂的淀粉酯膜更为致密,表面相对光滑,气密性更好。FT-IR表明,淀粉酯膜均成功塑化且具有相同峰型,说明不同塑化剂的塑化机理基本相同。TGA显示,热分解温度与塑化剂分子大小及羟基含量存在密切关系。接触角分析表明,不同塑化剂对于淀粉酯膜的亲水性各不相同,其亲水性大小为山梨醇>甘油>壳聚糖>乙二醇。     

Constrained mixture design applied to the development of cassava starch-chitosan blown films

Films composed of cassava starch, chitosan and glycerol were produced by blown extrusion and employing a design for constrained surfaces and mixtures. The effects of the components of the mixture on the mechanical properties, water vapor permeability (WVP) and opacity of the films were studied. According to the models generated by the design, the concentration of starch had a positive effect in all properties. The plasticizer glycerol and its interactions with other components had a positive effect on increasing the WVP. The presence of a higher relative concentration of chitosan favored the formation of more rigid and opaque and less permeable films. In general, the concentrations of starch, chitosan and glycerol led to changes in the film properties, potentially affecting their performance. The design for constrained surfaces and mixtures proved to be a useful tool for this type of study due to the complexity of the conditions of film formation.     

Preparation and properties of rice starch–chitosan blend biodegradable film

Biodegradable blend films from rice starch–chitosan were developed by casting film-solution on leveled trays. The influence of the ratio of starch and chitosan (2:1, 1.5:1, 1:1, and 0.5:1) on the mechanical properties, water barrier properties, and miscibility of biodegradable blend films was investigated. The biodegradable blend film from rice starch–chitosan showed an increase in tensile strength (TS), water vapor permeability (WVP), lighter color and yellowness and a decreasing elongation at the break (E), and film solubility (FS) after incorporation of chitosan. The introduction of chitosan increased the crystalline peak structure of starch film; however, too high chitosan concentration yielded phase separation between starch and chitosan. The amino group band of the chitosan molecule in the FTIR spectrum shifted from 1541.15 cm⁻¹ in the chitosan film to 1621.96 cm⁻¹ in the biodegradable blend films. These results pointed out that there was a molecular miscibility between these two components. The properties of rice starch–chitosan biodegradable blend film and selected biopolymer and synthetic polymer films were compared; the results demonstrated that rice starch–chitosan biodegradable blend film had mechanical properties similar to the other chitosan films. However, the water vapor permeability of rice starch–chitosan biodegradable blend film was characterized by relatively lower water vapor permeability than chitosan films but higher than polyolefin.     

Physicochemical,Microstructural, and Antibacterial Properties of β‐Chitosan and Kudzu Starch Composite Films

Abstract: This study investigated physicochemical, microstructural, and antibacterial properties of β‐chitosan–kudzu starch composite films with addition of 0%, 20%, 60%, or 100% kudzu starch (w starch/w chitosan) in 1% chitosan solution. Molecular interactions between chitosan and kudzu starch and the crystal structure of the films were also determined. Adding 60% kudzu starch reduced water vapor permeability and solubility of pure β‐chitosan film by about 15% and 20%, respectively, whereas mechanical strength and flexibility of the film were increased about 50% and 25%, respectively. Micrograph showed that β‐chitosan film was totally amorphous, and the composite films generally became rougher with more starch added. Fourier transform infrared and X‐ray diffraction spectra showed that the 2 film‐forming components were compatible with each other. Pure β‐chitosan film resulted in 9.5 and 11.5 log CFU/mL reduction in Escherichia coli and Listeria innocua based on plate count method, respectively. Addition of kudzu starch reduced the antibacterial activity of film, but still achieved 8.3 and 10.3 log CFU/mL reduction in E. coli and L. innocua, respectively when kudzu starch to chitosan weight ratio was 1:1. Reduced antibacterial activity might attribute to the interaction of amino groups in β‐chitosan with the hydroxyl groups in kudzu starch. This study demonstrated that kudzu starch effectively improved water barrier of β‐chitosan film, and the composite films retained strong antibacterial ability. Practical Application: One percent of β‐chitosan containing 60% kudzu starch (w/w chitosan) composite films possessed better mechanical and water barrier properties than pure β‐chitosan films, and showed strong antibacterial activity against both Gram‐positive and Gram‐negative bacteria. The films may be used as wraps or coatings to prolong the shelf life of different foods or other similar applications.     

甘油与甲基纤维素对高直链玉米淀粉- 壳聚糖复合膜性能的影响

以高直链玉米淀粉(HACS)和壳聚糖(CS)为基本材料,甘油为增塑剂,甲基纤维素(MC)为增强剂制备可食性复合膜,研究高直链玉米淀粉与壳聚糖的质量比,甘油的添加量以及甲基纤维素的添加量对复合膜物理性能的影响,包括抗拉强度(TS)、断裂伸长率(E)、水蒸气透过系数(WVP)和色度。结果表明,壳聚糖添加量的增大与甘油添加量的增加都使高直链玉米淀粉- 壳聚糖复合膜的抗拉强度降低,断裂伸长率和WVP 显著增大,膜颜色变黄;甲基纤维素的添加改善了复合膜的机械性能和WVP,随着甲基纤维素添加量的增加,复合膜的抗拉强度和断裂伸长率都随之增大,WVP 逐渐降低,且对膜的颜色没有显著影响。     

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.     

The water vapour permeability,mechanical properties and solubility of fish gelatin–chitosan films modified with transglutaminase or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and plasticized with glycerol

The effect of glycerol on the mechanical and water barrier properties, as well as on the water solubility, of fish gelatin–chitosan films (4:1, w/w) cross-linked with TGase or EDC was determined. The addition of glycerol in concentrations up to 30% (of the substrate mass) to the fish gelatin–chitosan films modified with TGase or EDC did not change their solubility in buffers of pH 3 and 6 at 25 °C or during heating at 100 °C for 60 min. The chemical and enzymatic cross-linking of the components did not increase the water barrier properties of the films. WVP of the films modified with EDC and TGase was not affected by glycerol at concentrations up to 25% of the substrate mass. Tensile strength of the films decreased after modification of the components with TGase or EDC, respectively, by about 25% and 40%. The elongations of the enzymatically modified films containing 20% of glycerol and of chemically modified films containing 15% of glycerol were, respectively, about 8 and 13 times higher than those of unplasticized films; however, the tensile strengths of plasticized films were, respectively, 2.5 and 5 times lower.     

胶原蛋白与壳聚糖复合膜的机械性能

以鮰鱼皮胶原蛋白与壳聚糖为原料制备可食用复合膜。通过正交试验考察胶原蛋白与壳聚糖的质量比、增塑剂种类及添加量、热处理温度及时间等工艺参数对可食用复合膜性能的影响。结果表明：胶原蛋白与壳聚糖质量比和热处理温度对拉伸强度影响较大;甘油添加量对复合膜断裂伸长率影响显著,而热处理时间对复合膜断裂伸长率有较小的影响。最佳机械性能复合膜制备工艺为：胶原蛋白与壳聚糖质量比为6∶4,甘油添加量（以总溶质计）20%、热处理温度为70 ℃、热处理时间为30 min。在此条件下,得到的复合膜表面光滑无气泡,拉伸强度为（21.98±0.33）MPa,断裂伸长率为（127.35±3.03）%。     

Thermal,mechanical and water adsorption properties of corn starch–carboxymethylcellulose/methylcellulose biodegradable films

The objective of this study was to investigate the effect of the addition of methylcellulose and carboxymethylcellulose on the thermal, mechanical and water adsorption properties of starch-based films plasticized with glycerol or polyethylene glycol (PEG). Mechanical tests showed that as the methylcellulose and carboxymethylcellulose proportion increased, starch films became more resistant to break, resulting in higher TS values. Besides there has been a positive effect on the elasticity of starch films realized by a considerable increase in E% values. Depending on the plasticizer type, either single or dual glass transitions were seen in DSC thermograms. One glass transition temperature was observed for films plasticized with glycerol, on the contrary, dual glass transitions were detected for PEG plasticized films. This behavior was attributed to the phase separation of the PEG. In addition, the presence of an endothermic peak in the thermograms of PEG plasticized films was taken as another indicator of the phase separation. As a result, it was suggested that PEG was not as compatible as glycerol with the composite polysaccharide matrix and plasticizer type was the main factor that shaped the thermal profiles of the film samples. Water adsorption isotherm data showed that samples displayed nonlinear sorption profile which is typical for hydrophilic films. In all films tested, equilibrium moisture contents, increased almost linearly up to a a_w of 0.65–0.85, beyond where a sharp increase was noted. Adsorption data was adequately fitted by BET and GAB models. Eventually, it can be concluded that film forming properties of starch can be improved by incorporation of methylcellulose and carboxymethylcellulose to the polymer matrix.     

豆腐渣/淀粉复合膜的制备及其性能

采用豆腐渣、淀粉为原料,以NaOH、丙三醇水溶液为溶剂,经加热溶解后制备豆腐渣/淀粉复合膜,并对复合膜的力学性能和溶液粘度进行了测试分析。利用二次通用旋转组合实验设计法,研究了NaOH浓度、豆腐渣/淀粉复配比、丙三醇含量对溶液粘度和复合膜断裂强度的影响。试验结果表明：NaOH的加入和豆腐渣/淀粉复配比是影响复合膜成膜性的重要因素。在NaOH浓度为1.7%,豆腐渣/淀粉复配比为1.135,丙三醇含量为0g时,复合膜的溶液粘度达到6.25kpa?s,断裂强度达到4.21Mpa。丙三醇作为增塑剂的加入,有利于改善复合膜的脆性。     

Mechanical properties of pea starch films associated with xanthan gum and glycerol

The aim of this study was to evaluate the effect of the addition of xanthan gum and glycerol to the starch of green pea with high content of AM (cv. Utrillo) in the preparation of films and their physical characteristics. Filmogenic solution (FS) with different levels of pea starch (3, 4, and 5%), xanthan gum (0, 0.05, and 0.1%), and glycerol (glycerol–starch ratio of 1:5 w/w) were studied. The FS was obtained by boiling (5 min), followed by autoclaving for 1 h at 120°C. The films were prepared by casting. Films prepared only with pea starch were mechanically resistant when compared to other films, prepared with corn, cassava, rice, and even other pea cultivars (yellow, commercial). The tensile strength of these films is comparable to synthetic films prepared with high‐density polyethylene and linear low‐density polyethylene. However, they are films of low elasticity when compared to other films, such as rice starch films, and especially when compared to polyethylene films. The increased concentration of starch in the solution increased the puncture force. The increased concentration of glycerol slightly decreased the film crystallinity and interfered in the mechanical properties of the films, causing reduction of the maximum values of tensile strength, strain at break, and puncture force. The plasticizer also caused an increase of elongation at break. Xanthan gum was important to formation of films; however, it did not affect their mechanical properties.     

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.     

Thermo-compression of biodegradable thermoplastic corn starch films containing chitin and chitosan

Films based on thermoplastic corn starch (TPS) and chitosan/chitin were obtained by melt-mixing and thermo-compression. Chitosan and chitin incorporation to TPS matrix induced some structural modifications due mainly to the interactions between starch hydroxyl and chitosan/chitin amino groups. Crystallinity degree of TPS films was increased with biopolymers incorporation. Enthalpy melting values for TPS–chitosan/chitin films resulted lower than those corresponding to TPS control ones. Films had homogeneous and smooth surfaces, without pores and cracks and no glycerol migration was evidenced by Scanning Electronic Microscopy. Films fracture surfaces were uniform without the presence of unmelting starch granules neither chitosan/chitin agglomerates. Films with chitosan/chitin presented higher color, UV absorption capacity and opacity than TPS films. Addition of 10 g chitosan or chitin/100 g starch decreased 35 and 56% water vapor permeability, respectively. Biopolymers addition to TPS increased tensile strength and elastic modulus, and decreased elongation at break. Starch and glycerol-rich domains where evidenced in TPS matrixes by Dynamic Mechanical Analysis. Finally, TPS–chitosan films reduced Staphylococcus aureus and Escherichia coli growth in the contact zone.     

小麦面筋蛋白的性质和转谷氨酰胺酶对其成膜性能的影响

以小麦面筋蛋白为研究对象,探讨小麦面筋蛋白的性质,转谷氨酰胺酶的作用和制备条件对膜性能的影响。结果表明,酶用量为20U/g,反应时间为120min,pH为11,甘油/谷朊粉1:2.5,塑料平板作为成膜介质和乙醇体积分数均为40%～50%时,膜的抗拉强度增加51%,阻水性提高23%,透光率提高了5.48倍。扫描电镜显示膜的超微结构更加细致光滑。说明蛋白质的性质对其成膜性能的影响至关重要,酶处理有助于改善膜的机械性能和透光性,选择合理的制备条件,可得到性能优良的小麦面筋蛋白膜。     

Microstructure and optical properties of sodium caseinate films containing oleic acid–beeswax mixtures

The effect of internal and surface structure of films obtained from sodium caseinate (NaCas), containing glycerol and lipid mixtures of oleic acid (OA) and beeswax (BW) (1:0.3:0.5 protein:glycerol:lipid ratio) on optical properties (gloss and transparency) was studied. Gloss was measured at different angles of the incident light (20, 60 and 85°) using a gloss meter, and transparency was evaluated through Kubelka–Munt coefficients obtained from the film reflection spectra (400–700 nm). Film structure was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Control films (without lipid) exhibited the greatest transparency and gloss whereas lipid imparts opacity and loss of gloss to the film, especially as beeswax increased in the lipid mixture, due to the formation of greatest lipid aggregates in the internal and surface parts of the film. Good correlation was established among gloss, transparency and surface roughness parameters of the films.     

茶多酚/还原石墨烯纳米复合物增强羧甲基壳聚糖薄膜性能的研究

目的 探究茶多酚还原氧化石墨烯(grapheneoxide,GO)的能力,进一步利用茶多酚/还原氧化石墨烯(reduced graphene oxide,RGO)改善羧甲基壳聚糖薄膜的综合性能。方法 首先利用茶多酚的还原性制备出茶多酚/RGO,通过X射线衍射仪(X-ray diffractometry,XRD)和傅里叶变换红外光谱仪(Fourier transform infrared spectrometer,FT-IR)表征验证。进一步以羧甲基壳聚糖为基材,甘油为塑化剂,通过流延法制备出一系列不同茶多酚/RGO含量的复合薄膜,测试其力学性能、阻隔性能、光学性能及热稳定性等,分析不同配比对复合薄膜性能的影响。结果 茶多酚和GO的质量比为2:1时,GO被还原的效果较好;与纯羧甲基壳聚糖膜相比,当茶多酚/RGO含量为2.0%时,复合膜的拉伸强度提高了96.9%;当茶多酚/RGO含量为1.0%时,水蒸气透过率最低,为7.0×10-13 [g·cm/(cm2·s·Pa)];随着茶多酚/RGO的添加,复合薄膜能够阻挡50%以上的310 nm以下的紫外光透过,表现出具有良好的抗紫外性。结论 茶多...