不同浓度戊二醛交联对明胶膜力学性能和热稳定性的影响

为了探究不同浓度戊二醛交联对明胶膜性能的影响,对其力学性能、热稳定性、溶胀度和降解率进行研究。将风干的明胶膜用质量浓度范围为0．05％～2．5％的戊二醛溶液处理。用三硝基苯磺酸法测定其交联度,在低浓度时,交联度可达到60％,当质量浓度大于或等于1％时可以达到100％。同时,明胶膜的可变形性降低,然而断裂应力汕和杨氏模量E则会升高。当戊二醛质量分数为0．25％时,交联度可达到85％,足以防止明胶在缓冲溶液中降解,从而明显减少其在生物溶液中的溶胀。此外,通过差示扫描热量法研究表明,交联对明胶膜样品热稳定性有很大的影响。为了获得稳定的、具有广泛应用范围的生物医学材料,建议实验在低浓度下进行,可以避免毒性和更好调整明胶膜的理化性能。     

4 种改性方式对明胶膜性能的影响

研究了共混改性、增塑改性、交联改性和乳化改性对明胶膜性能的影响。结果表明,明胶分别与壳聚糖、海藻酸钠共混溶解性较好,成膜均匀透明,同时具有较低的水蒸气透过率和透氧率,阻隔性增强;添加甘油作为增塑剂可提高明胶膜的断裂伸长率,机械性能增强;与柠檬酸钠交联改性后降低了明胶膜的水蒸气透过率,增强阻隔性能,提高抗拉强度,增强力学性能,但是膜的透光率下降;添加质量分数为0.1%的乳化剂吐温-80可以降低可食膜的水蒸气透过率,增强膜的阻隔性能,同时增大抗拉强度,改善机械性能。研究认为,共混、增塑、交联、乳化4 种改性方式均能不同程度地影响明胶膜的阻隔性能和机械性能,改善明胶膜的综合性能以满足其在不同领域的应用。     

胶原酶解物对双醛淀粉-明胶复合膜性质的影响

本文考察了罗非鱼皮胶原酶解物(TSCH)对双醛淀粉(DAS)交联明胶膜理化性质的影响,探讨了膜对人皮肤永生化角质(Ha Cat)细胞的相容性。结果发现,TSCH添加量从0增加至16%时,DAS交联明胶膜的抗拉伸强度从55.00 MPa下降至24.85 MPa,而断裂延伸率随着TSCH添加量的增加呈现先增大后减小的趋势。DAS交联明胶膜在30℃水中的溶解率为33.10%,当膜中TSCH含量超过4%后,膜的溶解率接近100%。然而,不管TSCH添加量是多少,经过240 min后膜中含有的TSCH全部释放到水中。SDS-PAGE的结果表明,在DAS交联明胶膜中添加的TSCH会阻碍明胶蛋白分子的相互交联作用。另一方面,将Ha Cat细胞培养于DAS交联明胶膜时,Ha Cat细胞活力只有11.39%,当DAS交联明胶膜中含有8%的TSCH时,Ha Cat细胞活力可以达到108.20%。以上结果表明,添加TSCH的DAS交联明胶膜在化妆品领域将具有一定的应用潜力。     

戊二醛不同程度交联明胶膜力学和热学性能

研究了戊二醛(GTA)交联明胶膜的力学性能、热稳定性、溶胀行为和后期释放量来验证GTA的用量对明胶膜稳定性的影响。明胶膜用其质量0.05%~2.50%的GTA溶液处理,然后用三硝基苯磺酸法测定交联度。结果显示:随着GTA用量从0.05%增加到1.00%以上,明胶膜的交联度从60%增加到100%。同时,明胶膜变形能力下降,而断裂应力δb和杨氏模量E增加。0.25%用量的戊二醛溶液交联后的明胶的交联度约为85%,在此交联度下的明胶已经不容易在缓冲溶液中溃散,同时其在生理溶液中的溶胀性也有所降低。此外,明胶膜在湿态及干态下的差示扫描量热分析结果表明交联程度极大地影响样品的热稳定性。数据表明为了防止其释放毒性,用以交联明胶的GTA用量不应太高,而且可以调节明胶膜的物理化学性能,同时也是为了获得具有广泛生物医学应用的稳定的明胶基材料。     

pH和双醛淀粉对罗非鱼鱼皮明胶膜性质的影响

考察了pH和双醛淀粉(DAS)对鱼皮明胶膜的机械性能和耐水性能的影响。结果表明,随着pH的升高,明胶膜的抗拉伸强度(TS)呈现先增加后降低的趋势,pH7时达到最大值(23.78MPa),而膜的固形物溶解率(MS)和蛋白溶解率(PS)逐渐下降。当明胶膜添加了DAS后,膜的TS显著增大(p<0.05),而MS和PS都显著下降(p<0.05)。另一方面,在pH7下,添加1.5%的DAS可有效提高膜的机械性能和耐水性能。SDS-PAGE分析结果表明,在成膜过程中pH对明胶蛋白组分没有产生明显的影响,DAS与明胶蛋白之间发生了交联反应。     

戊二醛不同程度交联明胶膜力学和热学性能

通过研究戊二醛(GTA)交联明胶膜力学、热学、膨胀和释放性能来验证GTA用量对明胶膜稳定性的影响.使用质量分数范围为0.05%～2.50%的GTA溶液处理风干的明胶膜,然后用三硝基苯磺酸法测定交联度.随着GTA质量分数从0.05%增加到1.00%以上,明胶膜的交联度从60%增加到100%.同时,明胶膜变形性下降,而断裂应力δb和杨氏模量E增加.用0.25%戊二醛溶液获得大约为85%的交联度已经足够防止明胶在缓冲溶液中释放,以及能使明胶在生理溶液中明显减少膨胀.此外,正如差示扫描量热法研究湿态膜和干态膜的结果所显示:交联程度极大影响样品的热稳定性.数据表明低用量的GTA可以防止它的毒性,而且可以调节明胶膜的物理化学性能.目的是为了获得具有广泛生物医学应用的稳定材料.     

兔皮、鸡皮和三文鱼皮明胶成膜性的对比

明胶作为可食性和可降解包装的主要材料,由于近年来食品安全问题及个人宗教信仰等,使得传统明胶不能大量应用,现亟需新型明胶材料的研究开发。为寻求最合适的明胶成膜材料,通过对阻隔性能、水溶性、力学性能、红外光谱分析和热稳定性分析来测定鸡皮、兔皮和三文鱼皮明胶的成膜性。最终表明:兔皮明胶膜的水蒸气透过率、水溶性、透氧率在三者中最低,也能表现出良好的机械性能,鸡皮明胶膜的热稳定性较好,但与兔皮明胶膜没有显著性差异。通过红外光谱图表明兔皮明胶膜酰胺A带的吸收峰最低,说明兔皮明胶中的羟脯氨酸和脯氨酸含量较多,酰胺Ⅰ分离子峰高斯拟合后发现兔皮明胶膜的三螺旋结构含量较多,同时甘油特征峰表示出甘油与兔皮明胶膜发生更多的交联。因此,兔皮明胶膜的各项性能优于鱼皮和鸡皮明胶膜,可以作为新型的明胶膜材料。     

桔子精油优化鱼鳞明胶膜性能的作用研究

为改善鱼鳞明胶膜的性能,测定添加明胶质量的0%、25%、50%、75%、100%桔子精油的可食膜的厚度、机械性能、水溶性、水蒸汽透过率、色泽、透明度和透光率、热性能、红外光谱和抑菌活性。结果表明:随着精油浓度的增加,鱼鳞明胶膜的厚度、断裂伸长率增加,拉伸强度、透光率、水溶性降低,水蒸汽透过率呈现先增加后降低的趋势;差示扫描量热法(DSC)和傅里叶变换红外光谱(FTIR)分析结果表明,鱼鳞明胶分子与桔子精油的部分成分发生相互作用,在一定程度上改善了明胶膜的热稳定性;桔子精油的添加还赋予了鱼鳞明胶膜抑菌作用。综合评价得出75%质量浓度的桔子精油添加量对鱼鳞明胶膜各项性能优化效果最好,本实验结果可为生产高性能的鱼鳞明胶膜提供理论基础。     

3种淡水鱼鳞明胶成膜性的比较

以水蒸气渗透率(WVP)、透明度、溶解度和透油率等性质为评价指标,研究淡水鱼(草鱼、鳙鱼、鲫鱼)鱼鳞明胶的成膜性能,研究其对哺乳动物皮(猪皮、牛皮)明胶膜的可替代性。结果表明:3种淡水鱼鱼鳞明胶膜的WVP均低于哺乳动物明胶膜,其中鲫鱼鱼鳞明胶膜的WVP最低;鱼鳞明胶膜的溶解度、透光度和透油率高于哺乳动物明胶膜,其中草鱼鱼鳞明胶膜的溶解度和透油率最高,鳙鱼鱼鳞明胶膜有最高的透光度但是透油率最低,鲫鱼鱼鳞明胶膜的溶解度、透光度最低。红外结果表明,不同明胶膜的结构相似,甘油的特征吸收峰表明甘油和哺乳动物明胶膜发生更多的交联。     

杨梅素和糖基化协同改性鱼鳞明胶可食膜

为提升纯明胶膜的综合性能以增强其应用性,该研究基于多酚和糖基化处理对明胶的改性作用,对罗非鱼鱼鳞明胶进行糖基化和添加杨梅素制备功能性可食膜。结果表明,糖基化处理联合添加杨梅素能协同提高鱼鳞明胶可食膜机械性能和光阻隔性能,而不影响鱼鳞明胶膜的阻水性。其中糖基化和杨梅素均能提升鱼鳞明胶可食膜机械性能和紫外阻隔性能,杨梅素提升了明胶膜的阻水性,而糖基化降低了明胶膜的阻水性。差示扫描量热法(differential scanning calorimetry,DSC)和扫描电子显微镜(scanning electron microscope,SEM)显示,杨梅素协同糖基化改性提高了单一改性方式的膜热稳定性,并使明胶膜表面更加光洁,且内部结构更加规律和致密。傅里叶变换红外光谱(founrier transform infrared spectometer,FTIR)以及二级结构分析表明,添加杨梅素和糖基化处理均能通过氢键和分子间作用力改变鱼鳞明胶分子结构,糖基化和添加杨梅素改性的互补作用使鱼鳞明胶分子的β结构转变为α螺旋和无规则卷曲,使膜的阻水性无显著性改变,但协同提高了鱼鳞明胶复合膜的机械性能。杨梅素添加协同糖基化作用有望成为一种潜在的可食明胶膜性能提升手段。     

Influence of natamycin loading on the performance of transglutaminase-induced crosslinked gelatin composite films

We investigated the effect of natamycin on the physicochemical properties of crosslinked gelatin films. Natamycin decreased the tensile strength, elongation at break and water vapour barrier of crosslinked gelatin films. The thermal stability of the crosslinked gelatin films varied considerably with natamycin amount. The crosslinked films gradually turned yellow-green in colour with increasing natamycin content. The aforementioned different influences were associated with the altered microstructure and crystallinity of the crosslinked films induced by increasing natamycin amounts. The performance changes in the films could be attributed to the increase in natamycin, resulting in enhanced natamycin crystallinity, which was confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. Moreover, the crosslinking reaction could confer resistance to damage in TGase-induced aggregation caused by natamycin crystallinity. Therefore, the findings in this paper will facilitate the development of gelatin-based food-contact film materials and provide theoretical direction for the packing industry.     

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.     

Genipin交联明胶/溶菌酶缓释抗菌膜材料的微结构与性能研究

针对亲水明胶膜材料对抗菌剂缓释能力较差的问题,采用生物交联剂(genipin)调节膜材料微结构,制备出新型控释明胶/溶菌酶复合膜材料。系统研究了复合膜材料的力学性能、水汽阻隔性能、膨胀性和热性质等物理性能,并用AFM研究了膜材料的表面微结构,探讨了其结构-性能之间的关系。结果表明:genipin交联显著改善复合膜材料的力学性能,TS值从9.72 MPa逐渐增加至18.80 MPa;复合膜材料的膨胀度(swelling)随genipin浓度增加急剧下降,从1316%降至~200%;genipin交联提升复合膜材料的热稳定性。复合膜材的表面粗糙度依赖于genipin浓度,在低浓度段(0~1.0%),膜材料呈现平整表面微结构;高浓度(2.0%)时,膜表面出现不规则的突起,变得粗糙。适度的genipin交联有助于形成有序的三维网络结构,改善复合膜材料的物理性能;高浓度的genipin过度交联明胶基质,形成团聚状聚集物,及弱化明胶分子间相互作用,进而弱化膜材料的水汽阻隔能力。     

Preparation and properties of dialdehyde carboxymethyl cellulose crosslinked gelatin edible films

Glycerol-plasticized gelatin edible films with a new kind of dialdehyde polysaccharide, dialdehyde carboxymethyl cellulose (DCMC) as crosslinking agent are successful prepared using casting techniques. The mechanical properties, thermal stability, light barrier properties, swelling behavior as well as water vapor permeability (WVP) of the gelatin-DCMC films are investigated. The results indicate that the addition of DCMC causes tensile strength (TS) and thermal stability to increase and elongation at break (EB) to decrease, suggesting the occurrence of crosslinking between gelatin and DCMC. The light barrier measurements present high values of transparency at 280 nm and low values of transparency at 600 nm of the gelatin-DCMC films, indicating that gelatin-DCMC films are very transparent (lower in transparency value) while they have excellent barrier properties against UV light. Moreover, the values of transparency at 280 nm increase with the increased DCMC and glycerol content, suggesting the potential preventive effect of gelatin-DCMC films on the retardation of product oxidation induced by UV light. Furthermore, the addition of DCMC can greatly decrease the water vapor permeability (WVP) and equilibrium swelling ratio (ESR) down to values about 1.5 × 10⁻¹⁰ g m/m² s Pa and 150%, revealing the potential of DCMC in reducing the water sensitivity of gelatin-based films. In common for hygroscopic plasticizer in edible films, the addition of glycerol gives increase of EB and WVP and decrease of thermal stabilities and ESR of the gelatin-DCMC films.     

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.     

Gelatin–pectin composite films from polyion-complex hydrogels

Preparation and properties of composite films from gelatin and low-methoxyl pectin from simultaneous reversible and permanent polyion-complex hydrogels are presented. Ionic interactions between positively charged gelatin and negatively charged pectin produce reversible physical hydrogels with homogeneous molecular arrangement that improve both mechanical and water resistance but do not alter thermal stability relative to single polymer gels. Subsequent addition of 0.3 weight percent (wt.%) glutaraldehyde crosslinks gelatin heterogeneously, due to the presence of domains with non-uniform crosslinking, as revealed by the structural analysis. Resulting interspersed permanent chemical hydrogel showed a decreased swelling attitude by nearly 10 fold relative to films from gelatin alone and further improved mechanical performance (tensile strength and elongation at break). Results demonstrate that simultaneously exploiting the specific reactivity provided by the functional groups of both biopolymers can be used to create unique new structures with improved properties and offer potential for tailoring these to a wide range of targeted applications.     

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。     

Effect of Gelatin Addition on Properties of Pullulan Films

The gelatin was added into pullulan films to improve their performances and lower their cost. The gelatin addition raised the tensile strength of the gelatin–pullulan composite films, and reduced the oxygen permeability. The cost of composite films was reduced comparing to that of the pullulan films. Moreover, the molecular interaction of the composite film was evaluated. The interactions of gelatin and pullulan in the composite films were detected, such as (1) formation of 2 glycosylated proteins; (2) improvement of β‐sheet content; (3) formation of the interchain hydrogen bond and a semicrystalline region. Therefore, the molecular interaction was the main reason for the performance improvement of the composite films.