明胶-溶菌酶/ZnO纳米复合抗菌膜材料构建与性能

本研究以温敏性的明胶为基材同时包埋有机/无机抗菌剂,企图实现抗菌剂的协同增效,扩大材料的抗菌谱,并系统研究抗菌材料表面结构、机械与阻隔性能随抗菌剂种类及计量的演变规律。溶菌酶/纳米氧化锌-明胶膜材料具有选择吸光性,在紫外区域有明显吸收峰,而在可见光区域透光率超过90%。溶菌酶/纳米氧化锌具有协同增效,扩大膜材料的抗菌谱,相对荷载溶菌酶或纳米氧化锌的膜材料,复合抗菌剂膜对大肠杆菌与枯草芽孢杆菌具有更强的抗菌效果。荷载溶菌酶或纳米氧化锌不改变明胶膜材料的表面微结构,两者在成膜及膜基质中的相互作用形成异质的膜表面,并影响蛋白网络结构,弱化膜材料的水汽及氧气阻隔性能。本研究为新型有机/无机复合抗菌膜材料开发提供理论依据。     

含硅藻土负载香芹酚复合体的明胶基缓释抗菌膜的制备与性能

本研究利用多孔结构的硅藻土负载香芹酚制备抗菌复合体,并将其加入至明胶基质中通过流延成膜法制备明胶基活性复合膜,探究复合体的添加量对明胶膜物理性能与抗菌活性的影响。扫描电子显微镜观察、傅里叶变换红外光谱等结果表明,香芹酚成功吸附于硅藻土孔隙内部及表面。随着复合体添加量的增加,明胶膜的厚度、断裂伸长率、水蒸气透过率和氧气透过率增加,而透光率、水溶性、含水量和拉伸强度降低,同时抗氧化和抗菌性能明显提高。当复合体的添加量为20%时,复合膜仍表现出较好的综合性能,其拉伸强度为15.13 MPa,断裂伸长率为67.43%,1,1-二苯基-2-三硝基苯肼自由基清除率为56.33%,对金黄色葡萄球菌和大肠杆菌的抑菌圈直径分别达到39.4 mm和23.7 mm。更为重要的是,与直接添加等量香芹酚的明胶膜相比,硅藻土负载后使得香芹酚在明胶膜中的释放速率更慢,明胶膜的抗菌性能更长效。该实验结果可为利用硅藻土等无机矿物质负载香芹酚等植物精油制备具有缓释性能的明胶基抗菌膜提供一定的参考。     

丝素/明胶共混膜的结构和性能

采用热风干燥法制备丝素/明胶共混蛋白膜,探讨了共混比例、交联剂对共混膜的性能和结构的影响。共混比例为50/50左右时,膜的断裂伸长率和伸长弹性率都较大。     

缓释抗菌膜的抗菌性研究

以大肠杆菌、枯草杆菌、霉菌为研究对象,研究了负载不同生物保鲜剂的抗菌膜的缓释性、透气性和抗菌性,结果表明:负载迷迭香、肉桂油、姜油、丁香缓释抗菌膜的释放率分别为90.6％、90.2％、89.0％、85.1％,水蒸气透过率分别为0.07584、0.2995、0.4185、0.1193 g/m2d;对大肠杆菌、枯草杆菌、霉菌都具有明显的抑菌效果.其中负载迷迭香的缓释抗菌膜的缓释性、透气性和抗菌性优良,具有良好的应用前景.     

抗菌海藻酸/明胶共混纤维的制备与应用

天然高分子独特的结构不仅赋予同合成高分子相当甚至更好的功能,而且常具有无(低)毒、良好生物组织细胞相容性、可生物降解性等.     

明胶/L-聚乳酸共混膜的制备与性能表征

L-聚乳酸(PLLA)和明胶共混改性后成膜,分析了共混膜的热性能、力学性能、形貌和亲水性。试验结果表明:明胶与PLLA共混对PLLA的热性能影响较小;当共混膜中明胶质量分数<20%时,可使共混膜保持较好的力学性能;加入甘油可降低共混膜的Tg,并提高其断裂伸长率,起到了一定的增塑作用;聚乳酸与明胶共混后可增加聚乳酸膜的亲水性并降低明胶膜的亲水性,明胶/PLLA共混膜为疏松多孔的结构。     

血浆胺氧化酶交联明胶及其产物结构表征与性能分析

以血浆胺氧化酶(plasma amine oxidase,PAO)作为交联剂,以明胶为原料,研究不同添加量的PAO在有无Cu2+添加作为辅助因子的条件下对明胶结构和流变学性能的影响.电泳实验结果表明,随着PAO添加量的增大,明胶的大分子质量条带含量增加;扫描电镜实验结果表明,随着PAO添加量的增大,明胶的结构越来越紧密...     

明胶改性壳聚糖膜性能研究

根据壳聚糖与明胶的相容性,制备了壳聚糖膜、壳聚糖/明胶共混膜,研究了增加明胶含量对膜的强度、拉伸位移、溶出率、吸水率的影响.采用FT-IR谱图和XRD谱图分析,研究了膜的微观结构,探讨了共混体系中壳聚糖与明胶的相容性以及分子间的相互作用.当明胶含量在30%时,改性壳聚糖膜的抗拉强度达到最大值;在10%时,它的拉伸断裂伸长达到最大值;20%时,改性膜的吸水率达到最低;改性膜的溶出率则随着明胶含量的增加而增大.     

有机化合物交联改性明胶的研究进展

综述了有机化合物对明胶的化学交联改性方法,包括醛类、烷烯类、糖类、植物单宁等对明胶的交联改性。     

双醛淀粉改性明胶膜的制备与性能研究

利用双醛淀粉(DAS)交联明胶,制备了DAS改性明胶膜,研究了DAS改性对明胶膜力学性能、溶胀性能、吸湿性能和热降解稳定性能的影响。结果表明:DAS能有效地与明胶发生交联反应。适量DAS的交联可大幅提高明胶膜的拉伸强度。DAS交联可赋予明胶稳定的结构,有效地降低明胶膜对水的敏感性。随着DAS用量的增加,明胶膜的平衡溶胀率逐渐降低。DAS交联可降低明胶膜的吸湿率,在DAS用量为3%～5%时,膜的平衡吸湿率最低。经DAS改性后,明胶膜的热降解温度升高,表明其耐热降解稳定性得到提高。     

Characterization of Fish-Skin Gelatin Gels and Films Containing the Antimicrobial Enzyme Lysozyme

ABSTRACT:  Fish skins are rich in collagen and can be used to produce food-grade gelatin. Films cast from fish-skin gelatins are stable at room temperature and can act as a barrier when applied to foods. Lysozyme is a food-safe, antimicrobial enzyme that can also produce gels and films. When cold-water, fish-skin gelatin is enhanced with lysozyme, the resulting film has antimicrobial properties. The objective of this study was to characterize the effect on strength and barrier properties of lysozyme-enhanced fish-skin gelatin gels and films, and evaluate their activity against potential spoilage bacteria. Solutions containing 6.67% fish-skin gelatin were formulated to contain varying levels of hen-egg-white lysozyme. Gels were evaluated for strength, clarity, and viscoelastic properties. Films were evaluated for water activity, water vapor permeability, and antimicrobial barrier capabilities. Fish-skin gels containing 0.1% and 0.01% lysozyme had pH (4.8) and gelling-temperatures (2.1 °C) similar to lysozyme-free fish-skin gelatin controls. However, gel strength decreased (up to 20%). Turbidities of gels, with or without lysozyme, were comparable at all concentrations. Films cast with gelatin containing lysozyme demonstrated similar water vapor permeabilities and water activities. Lysozyme was still detectable in most fish gelatin films. More antimicrobial activity was retained in films cast with higher lysozyme concentrations and in films where lysozyme was added after the gelatin had been initially heated. These results suggest that fish-skin gelatin gels and films, when formulated with lysozyme, may provide a unique, functional barrier to increase the shelf life of food products.     

Mechanical,Physical, Antioxidant,and Antimicrobial Properties of Gelatin Films Incorporated with Thymol for Potential Use as Nano Wound Dressing

The aim of this study was to determine the properties of gelatin films incorporated with thymol. Gelatin films were prepared from gelatin solutions (10% w/v) containing thymol (1, 2, 4, and 8% w/w), glycerol (25% w/w) as plasticizer, and glutaraldehyde (2% w/w) as cross‐linker. Cross‐likened films showed higher tensile strength, higher elongation at break, lower Young's modulus, lower water solubility, lower swelling, lower water uptake, and lower water vapor permeability. Incorporation of thymol caused a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus, increase in water solubility, decrease in swelling and water uptake, and increase in water vapor permeability slightly. The films incorporated with thymol exhibited excellent antioxidant and antibacterial properties. The antibacterial activity of the films containing thymol was greatest against Staphylucoccus aureus followed by Bacillus subtilis followed by Escherichia coli and then by Pseudomonas aeruginosa. Thus, gelatin films‐containing thymol can be used as safe and effective source of natural antioxidant and antimicrobial agents with the purpose of evaluating their potential use as modern nano wound dressing. Practical Application : This study clearly demonstrates the potential of gelatin films incorporated with thymol as natural antioxidant and antimicrobial nano film. Such antimicrobial films exhibited excellent mechanical, physical, and water activities and could be used as antibacterial nano wound dressing against wounds burn pathogens.     

Ultraviolet-B Radiation Induced Cross-linking Improves Physical Properties of Cold- and Warm-Water Fish Gelatin Gels and Films

Cold- and warm-water fish gelatin granules were exposed to ultraviolet-B radiation for doses up to 29.7 J/cm(2) . Solutions and films were prepared from the granules. Gel electrophoresis and refractive index were used to examine changes in molecular weight of the samples. Also, the gel strength and rheological properties of the solutions as well as the tensile and water vapor barrier properties of the films were characterized. SDS-PAGE and refractive index results indicated cross-linking of gelatin chains after exposure to radiation. Interestingly, UV-B treated samples displayed higher gel strengths, with cold- and warm-water fish gelatin having gel strength increases from 1.39 to 2.11 N and from 7.15 to 8.34 N, respectively. In addition, both gelatin samples exhibited an increase in viscosity for higher UV doses. For gelatin films, the cold-water fish gelatin samples made from irradiated granules showed greater tensile strength. In comparison, the warm-water gelatin films made from irradiated granules had lower tensile strength, but better water vapor barrier properties. This might be due to the UV induced cross-linking in warm-water gelatin that disrupted helical structures.     

Influence of Transglutaminase-Induced Cross-Linking on Properties of Fish Gelatin Films

ABSTRACT:  Fish gelatin (FG) is a potential alternative to current mammalian (beef and pork) gelatin. However, its physical and thermal properties limit its use in many applications. The treatment of microbial transglutaminase (MTGase) on FG could be a practical way to increase the use of FG films in various applications. Physical properties, barrier properties, and molecular weight change of FG films were measured. The viscosity of the MTGase-treated FG solution significantly ( P < 0.05) increased from 6.81 ± 0.65 cP to 35.04 ± 3.59 cP as the reaction time and concentration of MTGase increased. After employing 2% of MTGase into FG solution, the tensile strength increased from 48.03 ± 5.45 MPa to 68.00 ± 1.9 MPa, while percent elongation decreased from 13.1%± 2.90% to 1.47%± 0.05%. Oxygen barrier property was significantly ( P < 0.05) increased from 7.24 ± 1.48 cc·m/m²·d to 17.69 ± 3.08 cc·m/m²·d, while water vapor permeability was not statistically ( P < 0.05) different. The melting temperature ( T _m) measured by differential scanning calorimetry increased from 124.78 ± 1.98 °C to 158.49 ± 2.68 °C as the enzyme reaction time increased. The color values of L *, a *, and b * were changed from 95.56 ± 0.09 to 95.50 ± 0.06, from −0.17 ± 0.01 to −0.23 ± 0.00, and from 3.17 ± 0.04 to 3.47 ± 0.09, respectively. The opacity significantly ( P < 0.05) increased from 1.43%± 0.32% to 2.87%± 0.06%. SDS-PAGE results showed that the molecular weight of fish gelatin films increased when the MTGase reaction takes place.     

Water Vapor Permeability of Mammalian and Fish Gelatin Films

ABSTRACT:  Water vapor permeability of cold- and warm-water fish skin gelatins films was evaluated and compared with different types of mammalian gelatins. Alaskan pollock and salmon gelatins were extracted from frozen skins, others were obtained from commercial sources. Water vapor permeability of gelatin films was determined considering differences on percent relative humidity (%RH) at the film underside. Molecular weight distribution, amino acid composition, gel strength, viscoelastic properties, pH, and clarity were also determined for each gelatin. Water vapor permeability of cold-water fish gelatin films (0.93 gmm/m²hkPa) was significantly lower than warm-water fish and mammalian gelatin films (1.31 and 1.88 gmm/m²hkPa, respectively) at 25 °C, 0/80 %RH through 0.05-mm thickness films. This was related to increased hydrophobicity due to reduced amounts of proline and hydroxyproline in cold-water fish gelatins. As expected, gel strength and gel setting temperatures were lower for cold-water fish gelatin than either warm-water fish gelatins or mammalian gelatins. This study demonstrated significant differences in physical, chemical, and rheological properties between mammalian and fish gelatins. Lower water vapor permeability of fish gelatin films can be useful particularly for applications related to reducing water loss from encapsulated drugs and refrigerated or frozen food systems.     

Using Liquid Smoke to Improve Mechanical and Water Resistance Properties of Gelatin Films

Improvement of mechanical and water barrier properties is critical for gelatin films when applied to edible food packaging. A liquid smoke (LS) obtained from hawthorn nucleus was used to improve the performance of gelatin film based on its abundant compounds. Through SPME‐GC‐MS analysis, 86 volatile and semi‐volatile chemical compounds was detected in LS, in which the total carbonyl compounds were 27.60%, with the main aldehyde as 2‐furaldehyde (9.83%). For gelatin films, an observable influence of LS on film transparency was observed in gelatin films, but not for its thickness and microstructure. Desirably, adding LS into gelatin solution increased the tensile strength of the films, with a better value of 16.38 MPa as 3 wt% LS added, compared with the control (10.30 MPa). Accordingly, film elongation decreased with a LS dependent manner. Furthermore, the water resistance properties of gelatin film were improved by the LS addition, which was supported by the results of water contact angle, water vapor permeability. Moreover, the addition of LS also led to a higher insolubility for gelatin films. Also, thermal stability of the LS treated gelatin films was slightly enhanced with the DSC analysis. According to the FTIR spectra and crosslinking degree detection results, all the above enhancing of gelatin film should be attributed to the crosslinking between carbonyl groups in LS and amide functionalities in gelatin based on nucleophilic reaction.     

明胶/普鲁兰酶改性淀粉膜的制备与性能研究

研究了普鲁兰酶对淀粉膜性能的影响及明胶对普鲁兰酶改性淀粉膜性能的影响。结果表明:与原淀粉膜相比,普鲁兰酶改性淀粉膜的表面更平滑;膜的热稳定性增大,热封性能增强;抗拉强度、水蒸气透过率和透光率分别增加了75%、18%和35%,断裂伸长率降低了53%。与未添加明胶的酶改性淀粉膜相比,添加明胶后,膜的表面变粗糙;膜的阻水性能与阻光性能增强,热封性能变差。当明胶添加量为10%时,膜的抗拉强度增加了17.6%;当明胶添加量为25%时,膜的断裂伸长率增加了54.3%;在明胶添加量为15%时,膜的热稳定性最大。     

提高明胶可食膜机械强度和热封强度的研究

研究了明胶可食膜的机械强度和热封强度。结果表明：明胶可食膜的机械强度和热封强度受干燥温度的影响大,随干燥温度的升高,明胶膜机械强度和热封强度均呈先递增后递减的变化趋势,其最适干燥温度为６０℃;掺用少量琼脂（０．０２％）可明显改善明胶膜的机械强度和热封强度,特别是其断裂伸长率;用０．２％甘油增塑的明胶膜,其抗拉强度,直角撕裂强度均有所改善,但其热封强度稍有下降;明胶膜在贮藏过程中（－１８、０、２０、４０℃,相对湿度６５％）,其机械强度先递减后趋于稳定,但其热封强度变化不明显。