魔芋葡甘聚糖/乙基纤维素/玉米醇溶蛋白复合膜的制备与性能表征

本文在前期魔芋葡甘聚糖(KGM)与乙基纤维素(EC)复合膜的研究基础上,将玉米醇溶蛋白(zein)添加到KGM/EC复合膜液中,以流延方式制备了KGM/EC/zein三元复合膜。通过固定总固形物和较强疏水性成分EC的含量,研究了zein和KGM的含量变化对复合膜的微观结构、力学性能和耐水性能的影响。激光共聚焦显微镜、扫描电镜和显微红外结果表明,当zein添加量为总固形物含量的3%～9%时(对应KGM含量为67%～61%),成膜液和复合膜中各组分分布较为均匀,相容性较好,制备的复合膜微观结构致密。与K₇₀E₃₀复合膜相比,其耐水性能显著提高(P<0.05)。当KGM:EC:zein的固形物比例为64:30:6时,制备的复合膜性质最佳,其拉伸强度、断裂伸长率、水接触角、溶胀率和可溶性固体损失率分别为72.93 MPa、16.39%、104.2°、502.21%、15.50%。本研究为多糖/蛋白基复合可食膜的开发提供了参考。     

包载山苍子油的醇溶蛋白纳米粒子对明胶膜结构和性能的影响

本文以明胶、玉米醇溶蛋白和山苍子油为基材,通过流延法制备包载山苍子油的醇溶蛋白纳米粒子/明胶复合膜,研究了纳米粒子与明胶的相互作用,以及不同纳米粒子添加量对复合膜的透光性、微观结构、热稳定性、机械性能、疏水性、抑菌和抗氧化性能的影响。结果表明,纳米粒子与明胶之间发生了氢键相互作用,具有良好的相容性。随着纳米粒子添加量的增大,复合膜的透明度显著降低,其疏水性和抗氧化性显著增强（P<0.05）。复合膜对大肠杆菌和金黄色葡萄球菌均具有明显的抑菌活性,其抑菌圈直径分别为（9.17～10.00） mm和（10.02～11.10） mm。当纳米粒子分散液添加量为30%(v/v)时,复合膜的截面最致密,其热稳定性最好,断裂伸长率最大。本研究为开发含有山苍子油的食品活性包装材料提供了一定的参考依据。     

Rheological,mechanical and moisture sorption characteristics of cassava starch‐konjac glucomannan blend films

Cassava starch (ST)‐konjac glucomannan (KGM) blend films were prepared and their thermal, rheological, mechanical, moisture sorption properties and water vapour transmission rate were determined. Response surface methodology was employed for the preparation of films using different levels of ST, KGM and glycerol. All the filmogenic solutions exhibited shear thinning behaviour. Apparent viscosity and the dynamic rheological properties of filmogenic solutions varied considerably with KGM content. Rheological analysis revealed that the blend films are more appropriate than neat ST film for controlled drug release studies and for food coating. The melting temperature and enthalpy of fusion of the blend films were lower than that of neat ST film. When compared to neat starch film, the blend films showed broader peaks in DSC patterns, which suggests that incorporation of KGM decreased the crystallinity of ST. Mechanical properties, elongation at break and tensile strength of blend films were significantly higher (112.8% and 22.5 MPa, respectively) than those of neat ST film. Due to the more hydrophilic nature of KGM when compared to ST, the WVTR and moisture absorption of blend films were greater than that of neat ST film. Though KGM is more hydrophillic in nature, blend films with higher amount of KGM (0.643g) showed comparably lower values for both WVTR and moisture absorption than other blends. The solubility of the blend films was lower than that of neat starch film which also confirmed the strong intramolecular attraction between ST and KGM.     

Fabrication,Gastromucoadhesivity, Swelling,and Degradation of Zein–Chitosan Composite Ultrafine Fibers

Fabrication, via electrospinning, and characterization of an ultrafine structure architected from a blend of hydrophobic zein and hydrophilic chitosan (CS) were conducted. Poly(ethylene oxide) (PEO) and nonionic surfactant, namely, Tween^® 40, were employed to improve the electrospinnability of the blend, while ethanol was used as a solvent for zein. The effects of ethanol (EtOH) concentration (85% and 90%) and ratio of zein/PEO/CS (95/2.5/2.5 and 87.5/10/2.5) on the fiber morphology as well as gastromucoadhesivity against porcine stomach mucosa were then investigated; polymer‐mucosa adhesion was also investigated via Fourier‐transform infrared spectroscopy. Swelling and degradation of the composite ultrafine fibers were investigated under 2 simulated gastric conditions, namely, at pH 2 without pepsin and at pH 1.2 with pepsin. Using 85% EtOH as a solvent for zein resulted in a spider‐web‐like morphology; the maximum detachment force (MDF), which is an indirect indicator of the gastromucoadhesivity was nevertheless higher. Zein‐based ultrafine fibers exhibited higher MDF than the zein‐PEO‐CS composite; however, the cohesiveness of the composite fibers was higher. FTIR spectroscopic results indicated molecular interactions between the composite fibers and mucin functional groups. Swelling of the composite ultrafine fibers in simulated gastric fluid (SGF) at pH 2 without pepsin was not different from that in SGF at pH 1.2 with pepsin. Nevertheless, degradation of the composite fibers in SGF at pH 2 without pepsin was much less than that in SGF at pH 1.2 with pepsin; only 20% degradation was noted in the former case.     

油酸与甘油对玉米醇溶蛋白膜机械性能的影响及机理探讨

主要研究了两种性质不同的增塑剂(油酸和甘油)对玉米醇溶蛋白(zein)膜机械性能的影响和可能的机理,以抗拉伸强度(TS)、伸长率(E)、透水率(WVP)为指标,结果发现油酸和甘油都能显著改善zein膜的机械性能,且添加量都以20%(g/g zein)最优;复合增塑研究发现,当添加20%混合增塑液对zein膜进行增塑时,以油酸∶甘油为3∶1复合增塑的效果最好,其中与未增塑的zein膜相比,TS提高190%,E提高70%。进一步统计学分析表明,油酸与甘油在对zein膜增塑时有正协同作用。对未增塑、20%油酸增塑、20%甘油增塑及20%复合增塑(油酸∶甘油为3∶1)zein膜的玻璃态转化温度(Tg)及红外光谱(FT-IR)分析发现,增塑后的zein膜Tg有所下降,其中复合增塑降幅最大;FT-IR图谱分析发现,复合增塑时甘油的特征峰向高波长方向移动,显示增塑作用加强;蛋白二级结构分析发现,复合增塑后,二级结构虽有小幅改变,但并未达到显著水平,因此增塑剂与zein之间的非共价键相互作用(疏水力和氢键)可能是其增塑的化学基础。     

抗菌性玉米醇溶蛋白/壳聚糖复合膜的制备与性质

采用分步法,先配制壳聚糖/醋酸/乙醇溶液体系,再向其中加入玉米醇溶蛋白,最后利用流延法制成玉米醇溶蛋白/壳聚糖(zein/chitosan,Z/C)复合膜,探讨壳聚糖质量分数对Z/C复合膜理化性质与抗菌特性的影响。结果表明:在壳聚糖质量分数为2%~8%范围内,混合溶液的黏度和电导率随壳聚糖质量分数变化成阶梯状变化,且壳聚糖的添加对复合膜性质有显著影响,Z/C复合膜的断后伸长率从1.00%提高到6.67%,接触角从65.97°减小到53.61°,水蒸气透过率从5.23 g·m/(m2·h·Pa)提高到9.16 g·m/(m2·h·Pa);扫描电子显微镜观察,复合后薄膜保持光滑、均一;大肠杆菌抑菌实验表明添加壳聚糖使复合膜具有较强的抗菌特性。     

Nanofibre-based bilayer biopolymer films: enhancement of antioxidant activity and potential for food packaging application

This study aimed to enhance the antioxidant property of biopolymer film without the incorporation of external agents. The active bilayer film with improved antioxidant activity has been developed by electrospinning zein, a prolamine of corn as nanofibre (average diameter of 286 nm) on solvent cast chitosan film. Zein nanofibres exhibited a slight increase in antioxidant activity as compared to solvent cast zein film. But, zein nanofibre coating on chitosan films significantly improved its antioxidant activity from 12.41% to 44.17%. The developed bilayer films were evaluated for its ability to prevent browning in minimally processed apple slices and compared with those of chitosan and zein films plasticised with polyethylene glycol. Higher surface to volume ratio and better affinity of zein nanofibres in the bilayer film helped enhance its anti-browning ability. Thus, zein nanofibre-coated chitosan bilayer films can be used as an effective anti-browning packaging material for the packing of minimally processed fruits.     

EDC和NHS对玉米醇溶蛋白成膜性质的影响

为提高玉米醇溶蛋白膜的抗拉强度和伸长率,降低其水蒸气透过率和吸水率,研究交联剂1-乙基-3-（3-二甲基氨丙基）碳二亚胺盐酸盐（EDC）和N-羟基琥珀酰亚胺（NHS）对成膜性质的影响。结果表明：以90%乙醇为溶剂,EDC和NHS的添加量分别为0.06 g/g时,制得的膜性能最佳,抗拉强度为83 MPa,较未添加交联剂的蛋白膜提高97.6%;伸长率为5.5%,提高57.1%;水蒸气透过率为2.5×10-8（g·m）/（m2·h·Pa）,降低43.2%;吸水率为39.4%,降低24.4%;质量损失率为3.6%,增加20.0%;静态接触角为67.4°,表明膜表面仍为疏水表面。原子力显微镜观测显示,加入交联剂后,蛋白分子聚集体变小,以均一的小球型聚集体形式紧密有序排列。     

纳米TiO2对魔芋葡甘聚糖/玉米醇溶蛋白复合膜结构和性能的影响

本文以魔芋葡甘聚糖、玉米醇溶蛋白为成膜基质,添加不同含量（1%、2%、3%）的纳米TiO₂,以流延方式制备纳米TiO₂/魔芋葡甘聚糖/玉米醇溶蛋白复合膜,并对复合膜的微观结构、热性能、力学性能、疏水性、水蒸气透过率和抑菌性能进行了分析。结果表明,纳米TiO₂与魔芋葡甘聚糖、玉米醇溶蛋白间发生相互作用,有良好的相容性;添加纳米TiO₂使复合膜表面粗糙度增加,复合膜热稳定性和疏水性增强,力学性能降低;纳米TiO₂添加量为1% wt时,复合膜的水蒸气透过率（5.7×10?13 g·cm/（cm2·s·Pa））和溶胀率（16.4%）最小,水接触角值（99.6 °）最大;复合膜对金黄色葡萄球菌和大肠杆菌有明显的抑制作用,对枯草芽孢杆菌的抑制作用不明显。本研究为纳米TiO₂/魔芋葡甘聚糖/玉米醇溶蛋白复合膜作为包装材料的开发与应用提供一定参考依据。     

Wettability, surface microstructure and mechanical properties of films based on phosphorus oxychloride-treated zein

BACKGROUND: Zein, the predominant protein in corn, has been extensively studied as an alternative packaging material in edible and biodegradable films. However, films made from 100% zein are brittle under normal conditions. The aim of this investigation was to improve the film‐forming properties of zein by chemical phosphorylation. The surface hydrophobicity, surface microstructure and mechanical properties of films based on untreated and phosphorus oxychloride (POCl₃)‐treated zein were evaluated and compared. The effect of POCl₃ treatment on the rheological properties of zein solutions was also studied. RESULTS: POCl₃ treatment, especially at pH 7 and 9, led to an increase in the apparent viscosity of zein solutions. Atomic force microscopy (AFM) analysis showed that the film based on POCl₃‐treated zein at pH 7 had a stone‐like surface microstructure with a higher roughness (R_q) than the untreated zein film. The AFM data may partially account for the phenomenon that this film exhibited high surface hydrophobicity (H₀). POCl₃ treatment diminished the tensile strength (TS) of zein films from 4.83–6.67 to 1.3–2.29 MPa. However, the elongation at break (EAB) of the films at pH 7 and 9 increased from 3.0–4.5% (control film) to 150.1–122.7% (POCl₃‐treated film), indicating the potential application of zein films in wrapping foods or in non‐food industries such as sugar, fruit or troche that need good extension packing materials. CONCLUSION: The data presented suggest that the properties of zein films could be modulated by chemical phosphorylation treatment with POCl₃ at an appropriate pH value. Copyright © 2011 Society of Chemical Industry     

玉米-小麦淀粉/玉米醇溶蛋白双层膜热学及微观特性

研究了玉米-小麦淀粉成膜液与玉米醇溶蛋白成膜液不同配比制作的5 种可食用复合膜理化特性的差异, 并分别通过扫描电子显微镜观察、热重分析、差示扫描量热分析、X射线衍射分析、傅里叶变换红外光谱分析对其 热学特性和微观结构进行研究。结果表明：添加一层玉米醇溶蛋白后,双层膜阻水性提高,机械性能得到改善,由 扫描电子显微镜观察结果可知双层膜间结合紧密,热重分析和差示扫描量热分析结果显示双层膜热稳定性得到提 高,X射线衍射结果表明生物大分子之间相容性较好,傅里叶变换红外光谱分析结果发现双层膜间产生了新的氢键 等作用力,为玉米-小麦淀粉/玉米醇溶蛋白双层膜在食品包装中的应用提供了重要的参考依据。     

Effects of protein interactions on properties and microstructure of zein–gliadin composite films

Zein and gliadin are both readily dissolved in aqueous ethanol and have good film-forming property. This article describes an attempt to improve the flexibility of zein films by the addition of gliadin to the zein film-forming solution. The properties of zein–gliadin composite films, i.e., color, transparency, moisture content, water solubility, water vapor permeability, dynamic contact angle which in turn affected the mechanical property, water resistance and glass transition temperature of films were investigated. The contents of second structure were characterized via Fourier transform infrared spectroscopy (FTIR), whereas morphology of films was examined by scanning electron microscopy (SEM). It was observed that the addition of gliadin enhanced the strain at break of zein–gliadin composite films as a result of the increase in the content of α-helix, β-turn structures and decrease in the level of β-sheet structure. The water resistance of films decreased with the content of gliadin increasing. Morphology of composite films showed that gliadin and zein organized a homogeneous material. This work opens a new perspective for zein in flexible food package.     

Effect of plasticizing sugars on rheological and thermal properties of zein resins and mechanical properties of zein films

Zein is the most important protein in corn. Zein has good film forming properties. One of the film forming methods is production of zein resin and then thermomolding by hot press. Pure zein film is very brittle. Plasticizers can improve mechanical and film making properties of zein. In this research, sugars (fructose, galactose and glucose) were used as plasticizers and rheological properties of zein resin were studied by dynamic oscillatory tests for determination of plasticization effectiveness. Effect of plasticizers on thermal properties of resins was investigated by DSC at −100 to 150 °C. No crystallization and melting peaks related to zein and plasticizers were observed. As well as there was not significant difference at glass transition temperature between zein resins containing various sugars. Zein films were prepared from zein resins by rolling and hot press and then mechanical properties of films were measured. Films containing galactose had better tensile properties than other films and showed higher tensile strength, strain at break, and Young modulus than films containing fructose and glucose.     

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.     

高压湿热法改性玉米醇溶蛋白膜的工艺优化及性能分析

本研究采用高压湿热法对玉米醇溶蛋白膜进行改性处理,通过单因素实验和L₉（34）正交试验优化了高压湿热处理的工艺,并进行了性能研究。结果表明,最佳高压湿热处理条件为:成膜液体积9 mL、处理温度121 ℃、处理时间40 min。在此条件下玉米醇溶蛋白膜的吸水率低至11.35%±0.74%,浸水后透明度为181.30±3.29,相比未处理有显著改善（P<0.05）。同时,经过高压湿热改性后玉米醇溶蛋白膜的体外酶解抗性（14.92%±0.58%）和抗拉强度（16.51±2.13 MPa）明显增强。傅里叶红外光谱（FT-IR）分析表明,高压湿热改性导致玉米醇溶蛋白中β-转角结构向结构更加有序的无规则卷曲、β-折叠和α-螺旋结构转变。本文为高压湿热法辅助制备蛋白基高耐水性材料的开发提供理论基础。     

Influences of degree of hydrolysis and molecular weight of poly(vinyl alcohol) (PVA) on properties of fish myofibrillar protein/PVA blend films

Biodegradable blend films based on fish myofibrillar protein (FMP) and poly(vinyl alcohol) (PVA) were prepared and characterized. PVA with different degrees of hydrolysis (DH) and molecular weights (MW) had the impact on properties of FMP/PVA (1:1, w/w) blend film. The blend films with higher MW of PVA were more tensile resistant, as indicated by the greater tensile strength (TS) and elongation at break (EAB), while the films with PVA of lower DH were more flexible. The blend film with PVA-BP26 (DH: 86–98% mol; MW: 124,000–130,000 g/mol) exhibited the greatest tensile performance and the lowest water vapor permeability (p < 0.05), compared with other films. SEM and FTIR results revealed that FMP and PVA were compatible and their intermolecular interaction was enhanced, providing the blend film with desirable properties. Therefore, incorporation of PVA with appropriated DH and MW could improve the properties of the FMP-based film.     

An approach for the enhancement of the mechanical properties and film coating efficiency of shellac by the formation of composite films based on shellac and gelatin

The purpose of this study was to enhance the mechanical properties and film coating efficiency of shellac by the formation of composite films with different concentrations of gelatin. The composite films were prepared by the casting method and their mechanical and physicochemical properties were investigated. The results demonstrated that the puncture strength and percentage elongation of the composite film increased from 3.61 to 15.58 MPa and from 3.80% to 32.47% as the gelatin concentration increased to 50% w/w, respectively, indicating the enhancement of the strength and flexibility of the shellac film. The efficiency of the composite film over two model substrates, i.e., hydrophilic and hydrophobic substrates, respectively, was also studied. The work of adhesion and spreading coefficient of the composite film increased from 66.42 to 83.53 mN/m and from −8.14 to −3.07 mN/m for the hydrophilic substrate, indicating the improvement of the coating efficiency whereas the hydrophobic substrate showed the opposite trend with the increase in gelatin concentration. Therefore, the formation of the composite film not only improved the mechanical properties of shellac but also enhanced the efficiency of film coating by the modification of different concentrations of hydrocolloid polymer to suit with the type of coating substrate. Hence the knowledge of composite film could make beneficial contributions to the various applications in film coating for the food and pharmaceutical industries.     

Water vapour barrier and tensile properties of composite caseinate-pullulan films: Biopolymer composition effects and impact of beeswax lamination

The water sorption, water barrier properties and mechanical behaviour of pullulan (P) and sodium caseinate (SC), as well as their blend and bilayer films plasticized with sorbitol (25% dry basis), were investigated as a function of weight polymer ratio, water content and beeswax lamination. Very similar moisture sorption isotherms were obtained for blend and bilayer films with P/SC weight ratio of 1/3 and 3/1. Neither the type of film (blend or bilayer) nor the different P/SC ratio affected significantly (P > 0.05) the water vapour permeability (WVP) of the films. A mixture-process variable experimental design was applied to evaluate the effect of the proportion of the two polymers in relation with the relative humidity (RH, 53% and 75%) on the mechanical properties of the films. Increasing the P/SC ratio decreased the Young’s modulus (E), the tensile strength (σ_max) and increased the % elongation at break (% EB), suggesting that P imparts flexibility and SC stiffness to the composite films. With moisture content increase from 5% to 8% most of the films exhibited an increase in E and σ_max, whereas a sharp decline in both parameters and an increase in % EB were observed above this moisture level. The brittle to ductile transition of P coincided with its glass to rubber transition, whereas SC exhibited a ductile behaviour within the glassy state. The tensile characteristics of bilayer films at moisture content greater than 8% were dominated by the component present in higher proportion, while films made with the biopolymer blends showed mechanical behaviour closer to that of plain P films. Beeswax lamination of plain, bilayer and blend films resulted in a drastic decrease in water vapour permeance, whereas its effect on E and σ_max and in % EB was related to the mechanical properties of the hydrocolloid layers used and varied according to the moisture content of the films.     

Physicochemical Properties of Zein-Based Films by Electrophoretic Deposition Using Indium Tin Oxide Electrodes: Vertical and Horizontal Electric Fields

In this study, biodegradable and biocompatible zein films were prepared by electrophoretic deposition using indium tin oxide electrodes with two different modes: vertical and horizontal electric fields. The effects of the different mode of the electric field in the presence of ethanol on mechanical, hydrophobicity, water resistance properties, microstructures, and thermal stability of zein films were investigated. The results indicated that the physiochemical properties (tensile strength, hydrophobicity, water vapor permeability, water absorption, and thermal stability) of zein films prepared from the vertical electric field were superior to those of zein film produced from the horizontal electric field and the control. The results of scanning electron microscope demonstrated the presence of the compact and homogenous structures of zein films manufactured in electric fields. In summary, the knowledge achieved from this study could facilitate to prepare the zein-based films using a readily and scale-up method.     

鱼皮胶原纤维-淀粉复合膜的制备及性能研究

为明确鱼皮胶原纤维尺寸及其添加量对鱼皮胶原纤维-淀粉复合膜性能的影响,本研究利用醋酸预处理鱼皮(3、6、9、12 h)获得了不同尺寸的胶原纤维(CF3、CF6、CF9、CF12),考察了不同类型胶原纤维及其添加量对共混膜性能的影响。采用傅里叶红外光谱技术、差示扫描量热法及扫描电子显微镜对复合膜进行结构表征。结果表明:添加鱼皮胶原纤维后,复合膜的断裂伸长率和水蒸气透过系数均增加,溶解性降低;当CF3和CF6添加量分别为7.5%和10%时能增强复合膜的抗拉强度,而且以10% CF6制备的复合膜抗拉强度性能最好,添加CF9和CF12时,复合膜的抗拉强度呈降低现象。对添加10% CF6制备的复合膜和纯淀粉膜进行表征,发现胶原纤维与淀粉相容性良好,在成膜过程中,胶原纤维交错在淀粉膜中,两者之间形成了氢键,但复合膜的热稳定性下降。