Active warm-water fish gelatin film containing oxygen scavenging system

An oxygen scavenging system (OSS), composed of oxygen scavenging nanoparticles and iron chloride (II), was incorporated into warm-water fish gelatin film. Surface morphology, cross sectional images, and mechanical, barrier, and optical properties of the oxygen scavenging fish gelatin (OSFG) film were compared to those of the unmodified fish gelatin (UMFG) film. Results indicated that the OSS was well incorporated into the OSFG film structure. The OSFG film had rough film surface, increased water vapor and oxygen permeability, and decreased tensile strength due to the incorporation and agglomerations of the OSS. The incorporation of the OSS also caused color and haze alterations to the OSFG film. In addition, the oxygen scavenging capability of the OSFG film was investigated. The initial oxygen content (%) in the cup headspace, 20.90%, was decreased to 4.56% after 50 days of storage. The OSFG film had good oxygen scavenging capacity, 1969.08 cc O₂/m²/mil, and moisture was used as the activator to trigger the oxygen scavenging reaction.     

静电纺纳米纤维非织造布的湿传递性能

研究了静电纺纳米纤维的含气性。根据费克定律研究了静电纺纳米纤维非织造布的湿传递性能,分析了影响透湿性的关键因素——材料、厚度和纤维体积含量。深入研究了纤维体积含量对于湿阻的影响,在非织造布的厚度和纤维体积含量相近的条件下,纳米纤维非织造布比纺粘和水刺非织造布有相对较好的透湿性能。     

静电纺PA6纳米纤维膜的过滤性能

用98%甲酸溶解聚酰胺6(PA 6)制备质量浓度为13%纺丝液,经静电纺丝获得厚度31～60μm、纤维平均直径217 nm、表面平均孔径为234 nm的纳米纤维非织造膜.由于该纤维膜的断裂强度仅为8.06 MPa,实验以普通聚酯纤维织物为支撑基布,测试了不同样品的过滤性能.结果发现:在气流速度为2.83 L/min时,...     

静电纺纳米纤维材料的发展现状与应用

介绍静电纺纳米纤维的优势,纳米纤维静电纺丝加工技术发展历程,以及静电纺纳米纤维材料的应用领域,展望静电纺纳米纤维材料的发展。     

静电纺PA 6纳米纤维膜的力学性能研究

利用静电纺丝可形成由纳米级纤维组成的纳米纤维膜,由于该膜孔径小并具有高比表面积和高孔隙率,可用作组织工程支架、传感器感知膜、过滤材料和防护材料等。静电纺纳米纤维膜的力学性能对其适用性和耐用性有重要影响。以PA 6甲酸溶液进行静电纺丝,研究了纺丝液喂入速度和纺丝距离对静电纺PA 6纳米纤维膜力学性能的影响。结果表明:纺丝液喂入速度较低时,形成的纳米纤维膜力学性能差;纺丝距离增大时,纳米纤维膜的断裂强度降低;PA 6溶解于98%甲酸中配制成13%(质量分数)纺丝液,在喷嘴口径0.9 mm、电压30 kV下进行静电纺丝,纺丝液喂入速度在0.2～0.3 ml/h、纺丝距离为8～10 cm时可获得具有良好力学性能的PA 6纳米纤维膜。     

静电纺锡/聚丙烯腈纳米纤维膜制备与表征

将纳米锡(Sn)与聚丙烯腈(PAN)共混,采用静电纺丝法制备Sn/PAN纳米纤维膜并进行炭化处理。使用扫描电子显微镜、透射电子显微镜和X射线衍射法对纤维平均直径、直径分布、Sn在纤维上的存在情况以及Sn加入到PAN中静电纺丝后的结晶程度进行表征,将炭化后的纤维膜直接制成锂离子电池负极,测试其电化学性能。结果表明:随着纺丝电压升高或固化距离增大,纤维直径减小;当静电纺丝电压为14 kV,固化距离为14 cm时,纤维平均直径较小,分布最均匀;炭化后纤维变细;Sn加入到PAN中静电纺丝后发生团聚,结晶程度明显下降;Sn/PAN作为锂离子电池负极材料,具有良好的储能性能。     

鱼鳞明胶的泡沫性能

以鳙鱼鱼鳞为原料提取鱼鳞明胶,利用泡沫扫描仪测试泡沫形状,泡沫参数,泡沫粒径分布,泡沫起泡性、泡沫稳定性以及泡沫表面扩张黏弹性等,进而对明胶泡沫的性质与时间和浓度的关系进行对比分析。结果发现:明胶泡沫随着时间和浓度的改变而有所不同,随着时间的延长泡沫逐渐变大,且泡沫形状由最初的球形逐渐变为多边形;浓度为0.2%的明胶液泡沫粒径最小,起泡能力最强,泡沫稳定性最高。     

Comparison of the properties of multi-composite fish gelatin films with that of mammalian gelatin films

Four types of films viz. gelatin, gelatin–MMT, gelatin–chitosan and gelatin–MMT–chitosan prepared from redsnapper and grouper bone gelatin were compared with the mammalian gelatin films, for their mechanical and barrier properties. Grouper gelatin films had higher tensile strength (TS) and Young’s modulus (YM), but lower elongation at break (EAB) than redsnapper films. Incorporation of MMT and chitosan improved the TS (p < 0.05) of the films. Water solubilities were lower (p < 0.05) in films incorporated with chitosan compared to simple gelatin film. Protein solubilities were lower in gelatin–MMT films, irrespective of the type of solvent used. The water vapour transmission rates (WVTR) of fish and mammalian gelatin films were similar, but addition of MMT had reduced WVTR (p < 0.05). SEM micrographs depicted smoother surface for gelatin–MMT and gelatin–MMT–chitosan films. Thus, composite fish gelatin films made with MMT and chitosan could be the good natural biodegradable films due to their better mechanical and barrier properties.     

Characterization of a starfish gelatin film containing vanillin and its application in the packaging of crab stick

To explore the use of starfish gelatin (SFG) films as a biodegradable material, SFG from starfish was extracted and used as a film material. In addition, to provide antimicrobial activity and enhanced flavor of SFG films, vanillin was incorporated. As the concentration of vanillin increased, the tensile strength of the films increased and water vapor permeability decreased. With regard to the structural characteristics of SFG films containing vanillin, the microstructure of the SFG films was not affected by the addition of vanillin. In addition, the SFG films containing vanillin exhibited antimicrobial activity against Listeria monocytogenes. As the application of the SFG films, crab sticks were packed with SFG films containing 0.05% vanillin. During storage, the populations of L. monocytogenes inoculated on crab sticks wrapped with SFG films containing vanillin were lower than those on the control sample, suggesting that SFG films containing vanillin can be useful in active food packaging.     

Preparation and functional characterisation of fish skin gelatin and comparison with commercial gelatin

Gelatin was extracted from the skin of farmed giant catfish (GC) and tilapia (TP) at a yield of 19.50% and 23.34% (wet wt). It was high in protein (84–88%) but low in fat (0.09–1.24%) and ash content (0.15–0.17%). The GC exhibited lower emulsifying activity (24–35%), but greater foam ability (98–110%), water holding capacity (477–844%) and fat binding capacity (2541–3314%) than commercial beef skin gelatin (BF) (P < 0.05). GC and TP showed comparable functional properties to BF. SDS‐PAGE patterns of TP gelatin showed high band intensity for the α‐ and β‐components, while the lowest band intensity of the major component was found in the BF. From the study, it can be concluded that the farmed freshwater fish skin GC and TP is a prospective source for producing a significant gelatin yield with desirable functionalities. Because of these, fish skin gelatin could be more effectively and widely used in food industries as a good food ingredient.     

PA6/Ag/TiO2共混静电纺纳米纤维毡的结构与性能

选用聚酰胺6(PA6)作为基体,以纳米Ag和TiO2粉休为功能件添加材料,采用静电纺丝法制备了抗菌复合纳米纤维毡.在纳米粉体质量分数一定的条件下,研究2种粉体的比例与纤维形态、结品结构及力学性能的关系.纳米粉体的加入,有效地提高了PA6纤维的结晶度和拉伸强度;Ag和TiO2的比例对纤维结构的影响不大;纳米Ag单组分添加...     

Preparation and characterization of crosslinked electrospun pullulan nanofiber membrane as a potential for biomaterials

Pullulan nanofiber membrane (Pull-NM) was prepared by electrospinning method and its stability in the water was improved by a chemical crosslinking with mixed solution of ethylene glycol diglycidyl ether (EGDE) and ethanol absolute as crosslinking agent. The effect of crosslinked pullulan nanofiber membrane (C-l-Pull-NM) with different process conditions was studied and the excellent crosslinking reaction condition is proved to be 1:70 (EGDE: ethanol absolute) for 24 h. The analytical methods, including SEM, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and differential scanning calorimetry, were used to study morphology, structure, and thermal performance of the nanofiber membrane. In addition, the swelling behavior and tensile were also discussed. The results showed that the water resistance of crosslinked nanofiber membrane had a significant improvement. Furthermore, the maximum water absorption and the strength were reached to about 520 and 192.7%, respectively.     

Ultraviolet irradiation improves gel strength of fish gelatin

Preliminary studies were undertaken to investigate the impact of ultraviolet (UV) irradiation on the gel strength, viscosity, and thermal properties of a commercially procured fish gelatin sample. Fish gelatin samples (dry granules) were exposed to UV irradiation for 30 and 60 min. Irradiated samples exhibited significant improvement in the gel strength, marked reduction in viscosity, with significant changes in the melting enthalpy. Results indicated the prospects of employing UV radiation as an alternative method over conventional means for improving some of the quality attributes of fish gelatin.     

含氟聚氨酯/聚氨酯纳米纤维膜复合织物的制备及其防水透湿性能

为获得良好防水性能且保持服装穿着的舒适性,通过构建具有低表面能和粗糙表面于一体的含氟聚氨酯/聚氨酯纳米纤维膜,以涤/棉斜纹机织物作为静电纺丝接收基布,制备了一种新型防水透湿织物。探讨了含氟聚氨酯疏水剂的质量分数对纳米纤维结构及复合织物的防水透湿和力学性能的影响。结果表明,当含氟聚氨酯疏水剂质量分数为100%时,复合织物性能最佳,其静态接触角为141°,透湿率达到3 958 g/(m2·24 h),,沾水等级为5级透气率达到34.06 mm/s。力学性能测试结果表明,复合织物的力学性能随疏水剂质量分数的提高而逐渐增强,当FPU质量分数为1.00%时,顶破强力、撕裂强力和拉伸强力分别增加了5.93%、30.79%和5.48%。     

Characterization of fish gelatin from surimi processing wastes: Thermal analysis and effect of transglutaminase on gel properties

Fish gelatin extraction from wastes of fish Herring species (Tenualosa ilisha) was carried out by a series of pretreatment with 0.2 M Ca(OH)₂ followed by 0.1 M citric acid and final water extraction at 50 °C for 3 h. The resulting fish gelatin preparation was evaluated for its dynamic viscoelastic properties, gelling and melting temperatures and gel strength. The gelling and melting temperatures of gelatin samples (at 6.67%, w/v) were obtained from differential scanning calorimetry and rheological studies. The melting temperature of extracted fish gelatin (EFG) obtained ranged from 16.2 to 16.7 °C compared to that of commercial fish gelatin gel (CFG), from 23.7 to 25.6 °C and halal bovine gelatin (HBG), from 26.5 to 28.7 °C. On the other hand, gelling temperatures of EFG, CFG and HBG ranged from 5.1 to 5.2 °C, 11.9 to 17.46 °C, and 12.6 to 19.33 °C, respectively. EFG gave gels with a considerably lower G′ values than CFG and HBG. The bloom strength of EFG gels at 6.67% (w/v) was 69.03 g which was much lower than HBG (336.2 g) and CFG (435.9 g). Enzyme transglutaminase was added in the amounts of 0.5, 1.0, 3.0 and 5.0 mg/g gelatin to modify the gel properties of the extracted fish gelatin. The modified EFG gels obtained had higher gel strengths of 101.1 g and 90.56 g with added transglutaminase of 1.0 and 3.0 mg/g, respectively. However with addition of 5.0 mg/g enzyme the gel strength increased only up to 75.06 g. SDS-PAGE of extracted gelatin gel showed protein band intensities for α1-chains and 53 kDa but in gels added with higher concentration of transglutaminase, these protein band intensities seemed to disappear.     

Role of lignosulphonate in properties of fish gelatin films

A commercial low-gelling fish skin gelatin was used to prepare edible films by casting with glycerol and sorbitol added as plasticizers. In order to improve the extremely low water resistance of gelatin films, composite films were prepared with increasing concentrations (wt/wt) of lignosulphonate (LS) from eucalyptus wood (100:0, 85:15, 80:20, 75:25, 70:30 and 65:35, gelatin:LS). How gelatin film properties were affected by the different types of gelatin and LS was determined by comparing bovine gelatin and three different LS (Ca²⁺, Mg²⁺ and Na⁺) in a mixture ratio of 80:20. Physical properties of films were characterized in terms of tensile strength, elongation at break, water solubility, water vapour permeability and opacity. Dynamic oscillatory tests of film-forming solutions revealed strong LS interference with the cold-renaturation ability of gelatin. LS ratios equal to or higher than the 80:20 blend interfered with intermolecular aggregation of gelatin helices. Supposedly, LS acted as a filler, inducing mostly nonbonding interactions with gelatin, as deduced from Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC) studies. Lignosulphonate significantly reduced the elongation at break of fish gelatin films, water solubility being drastically reduced with a mixture ratio of 80:20 or higher. The water solubility of bovine gelatin-LS composite films was significantly lower than that for fish gelatin, regardless of the type of LS employed. For potential food packaging applications, the three LS were characterized in terms of cytotoxicity, radical scavenging capacity (DPPH assay) and antimicrobial capacity. The effective antioxidant levels (IC₅₀: 83.4-97.5 μg/mL) were noticeably lower than the cytotoxic ones (IC₅₀: 1480-1745 μg/mL), indicating that these compounds could be used as antioxidants at non-cytotoxic concentrations. No relationship between antioxidant and antimicrobial properties could be observed, the only notable antimicrobial finding being some activity against yeasts.     

Enzymatic hydrolysis of fish gelatin under high pressure treatment

The effect of high pressure treatment on the hydrolysis of fish skin gelatin and the antioxidant properties of the hydrolysates was evaluated. Hydrolysis was performed by Alcalase, collagenase, trypsin and pepsin both at atmospheric pressure and under high pressure (100 MPa/15 and 30 min, 200 MPa/15 and 30 min, 300 MPa/15 min). The degree of hydrolysis (DH) was determined according to the base consumption via pH‐stat as well as the percentage of soluble nitrogen in trichloroacetic acid (TCA). About 16% of nitrogen in the gelatin was still soluble in 10% TCA, indicative of a significant amount of low molecular weight components. The high pressure treatment increased the DH with all the enzymes used between 5% and 10%. However, in comparison with the hydrolysates obtained at atmospheric pressure after 3 h of digestion under controlled conditions (using a pH‐stat), the radical scavenging capacity of the pressured hydrolysates was only significantly enhanced when Alcalase or collagenase were used. High pressure may be a useful tool for the quick obtaining of gelatin hydrolysates with antioxidant capacity.     

涤纶织物复合静电纺PVDF纳米纤维防水透湿膜的工艺探索

采用热轧工艺复合涤纶织物和静电纺聚偏四氟乙烯(PVDF)纳米纤维膜,开发具有防水性、透湿性、透气性的复合织物。探讨纺丝液中PVDF质量分数和纺丝电压对PVDF纳米纤维膜形貌的影响,测试采用3种复合工艺制得的单层膜复合织物、单面双层膜复合织物和双面单层膜复合织物的瞬时接触角和动态接触角,以及单层膜复合织物的透湿性、透气性和力学性能。结果表明:纺丝液中PVDF的质量分数为23%、纺丝电压为15、16 kV时,可制得纤维直径为300~400 nm且粗细均匀的PVDF纳米纤维膜;单层膜复合织物、单面双层膜复合织物和双面单层膜复合织物的接触角分别为135.1°、142.4°和136.7°,8 min后接触角的降幅分别为5.40%、10.57%和10.31%;与涤纶织物原样相比,单层膜复合织物的透气率下降35.53%,透湿量下降6.93%,力学性能提高。     

Use of lactic acid for extraction of fish skin gelatin

The ability of lactic acid compared to acetic acid for Dover sole (Solea vulgaris) skin swelling and the subsequent gelatin extraction was examined. The resultant gelatins were evaluated in terms of extraction yield, amino acid composition, molecular weight distribution, gel strength, viscoelastic properties, ability to refold into triple helical structures, and aggregation phenomena. Lactic acid (25 mM) proved to be an excellent substitute for acetic acid during the skin swelling process, as the gelatin preparation thus obtained presented quite similar properties to that prepared by using 50 mM acetic acid without the negative organoleptic properties of this acid. However, the application of 50 mM lactic acid gave rise to a highly hydrolysed gelatin, with lower folding ability, gel strength and viscoelastic properties than those obtained using 25 mM lactic acid or 50 mM acetic acid.     

Effects of adding fish gelatin on Alaska pollock surimi gels

Fish gelatin is a food additive obtained after hydrolysis of collagen from fish skin. The importance of fish gelatin as a food additive is increasing due to its increased commercial availability. Surimi is washed minced fish meat used as the raw material for seafood analogs like crabmeat substitutes. The most important attributes of surimi are gelling and whiteness. The objective of this work was to determine the effect of using fish gelatin as an additive in surimi to improve the mechanical and functional properties of gels. Surimi gels were prepared by mixing grade A or FA surimi (Alaska pollock) with salt (20 g/kg w/w) and commercial fish gelatin at 0 (control), 5, 7.5, 10, or 15 g/kg (w/w) previously dissolved in water (200 mL/kg surimi). The solubilized paste was incubated at 40 °C for 30 min followed by cooking at 90 °C for 15 min. Changes in mechanical properties (torsion test), a functional property (expressible water content) and color attributes of surimi gels were measured. Grade FA surimi gels containing 7.5–15 g/kg of fish gelatin showed an improved expressible moisture. However, gelatin added at 15 g/kg showed a disruptive effect detrimental to the mechanical properties. Color parameters were modified slightly. Whiteness attribute as affected by increasing the fish gelatin was instrumentally detected but not observed by sensory panelists. Gelatin did not change the overall color attributes and all gels remained in the grayish region. These results indicated that fish gelatin did not have an advantage for using as a functional additive in Alaska pollock surimi grades A or FA. However, it can be used at up to 10 g/kg without a negative effect on the mechanical properties.