海藻酸钠对鱼皮明胶膜理化特性的影响

采用罗非鱼皮明胶与海藻酸钠混合制备可食性复合膜,研究海藻酸钠含量对复合膜理化性质的影响。结果显示：单一罗非鱼皮明胶具有良好的成膜能力,但是机械性能差,将海藻酸钠添加到明胶膜中得到的复合膜抗拉强度和断裂伸长率有明显改善,海藻酸钠添加量在40%时,抗拉强度达最大值6.6?MPa,相对于纯明胶膜（5.5?MPa）和纯海藻酸钠膜（4.6?MPa）分别增加20%和43%,断裂伸长率也在此时达到最大值120%,比纯明胶膜（64%）和纯海藻酸钠膜（88%）分别增加87.5%和26.7%。海藻酸钠水溶性和吸湿率分别高达100%和48.7%,经共混后复合膜的水溶性降低至55%以下,吸湿率介于25%～40%之间,有较大的改善。流变学特性和X射线衍射分析结果表明：明胶和海藻酸钠具有良好的相容性,二者共混可制得性质稳定的复合膜,海藻酸钠与明胶的复合膜液为非牛顿流体,黏度和增稠能力较单一明胶膜有所增加。     

海藻酸钠-鱼明胶复合可食膜的制备及特性研究

为改善鱼明胶和海藻酸钠单一可食膜的各项性能,以鱼明胶为主体,辅以不同浓度的海藻酸钠,以3%(质量浓度)甘油为增塑剂,使用流延法制备海藻酸钠/鱼明胶复合可食膜。将海藻酸钠和鱼明胶单一膜为对照,分析不同海藻酸钠-鱼明胶比例对可食膜水蒸气透过率、溶解性、含水量、色差值、抗拉强度、抗菌能力及保鲜效果的影响。结果表明,通过复合,可食膜的各项性质较单一膜均有所改善。随着海藻酸钠∶鱼明胶质量配比由1∶9增至1∶1,复合膜的水蒸气透过率由6.19 gm^-1d^-1MPa^-1降至2.80 gm^-1d^-1MPa^-1,溶解率由61.60%增至73.92%,阻水性与溶解性均显著提高;而随着鱼明胶质量浓度由25 g/L增至45 g/L,复合膜拉伸强度显著增加,且当鱼明胶质量浓度为45 g/L时,膜的拉伸强度达到最大值(458.00 g·f)。此外,单一膜和复合膜均表现出对金黄色葡萄球菌和大肠埃希氏菌有良好的抑菌活性。     

柚皮果胶-海藻酸钠可食复合膜对草莓的保鲜

以自制柚皮果胶和海藻酸钠为基材制备的柚皮果胶-海藻酸钠可食复合膜具有良好的阻隔性能、力学性能。以柚皮果胶-海藻酸钠可食复合膜为保鲜包装材料,考察不同包装处理对草莓的感官品质、营养成分、MDA含量及SOD活性的影响。结果表明,以该复合膜托盘包装和以复合膜液涂抹+PE膜托盘包装的保鲜效果极显著于其他各处理组,能有效降低草莓的失水率、腐烂率和MDA含量的增加,减少草莓果实的可溶性蛋白质、可溶性固形物、Vc含量和SOD活性的降低,在短期内有效保持草莓的感官品质和营养成分,延长贮藏时间。以复合膜液涂抹+PE膜托盘包装方式的保鲜效果最好,可替代传统PE膜的托盘保鲜方式。     

海藻酸钠对可食性复合膜性能的影响研究

在均匀实验设计方法得到乳清分离蛋白-酪蛋白酸钠复合蛋白膜的工艺参数的基础上,采用乳清分离蛋白、酪蛋白酸钠、海藻酸钠共混法制备可食性复合膜,研究海藻酸钠对复合膜的性能的影响。结果表明,适当浓度和比例的海藻酸钠能提高膜的机械性能和水溶性,但也降低了膜的透明度和阻隔性能。     

海藻酸钠-结冷胶复合膜的性能与应用研究

将海藻酸钠-结冷胶复合膜与其他海藻酸钠复合膜进行性能对比,突出优越性,同时探究该复合膜的应用方向。选取明胶和硬脂酸分别与海藻酸钠复合成膜,测定不同膜液总浓度、组分比例、交联浓度条件下的透水率和溶胀度情况,和海藻酸钠-结冷胶复合膜进行抗水性对比;测试该复合膜的耐油性和耐盐水情况以考察在其他方面的可应用性。结果表明:海藻酸钠-结冷胶复合膜相对其他两种复合膜抗水性更高,在油温超过80℃后透油率和溶胀度趋于稳定,分别为2.867×10^-7 g/(m·s·Pa)和11.13%;其对盐水的阻隔性能对盐水浓度的变化不敏感,透水率和溶胀度分别为7.78×10^-7 g/(m·s·Pa)、71.9%。     

明胶α亚基和美拉德反应对明胶-海藻酸钠复合膜性质的影响

以罗非鱼皮明胶α1、α2亚基和海藻酸钠为原料制备复合膜,对膜的机械性能、颜色、荧光强度和傅里叶红外光谱(FTIR)进行分析,考察了α亚基和美拉德反应对明胶-海藻酸钠复合膜性质的影响。结果发现,α亚基-海藻酸钠膜的机械性能在60℃、相对湿度(RH)为75%下保存72 h后均出现明显的下降,而荧光强度均出现增强。α1-海藻酸钠(α1-SA)复合膜在放置72 h后,b*值的增大幅度达到64.0%,明显高于明胶-海藻酸钠(G-SA)和α2-海藻酸钠(α2-SA)复合膜。FTIR分析表明,保存过程中α亚基与海藻酸钠发生了美拉德反应,并且α1亚基更容易参与反应。因此明胶α亚基-海藻酸钠复合膜在60℃、75%RH下保存中颜色逐渐变黄。     

海藻酸钠-果胶改性复合膜的制备及表征

以海藻酸钠(SA)和柚皮果胶(PEC)为基材,辅以添加甘油和不同种类脂质制备复合膜,通过分析各组分对膜水蒸气透过系数、过氧化值、抗拉强度等指标的影响,确定复合膜的适宜配方:SA与PEC的质量比为10/2,甘油的添加量0.3%,石蜡添加量为0.12%。以CaCl_2、BaCl_2、FeCl_3、Al_2(SO_4)_3不同交联剂对该复合膜进行改性,以CaCl_2为交联剂,CaCl_2浓度3%、交联时间3min条件下制备的海藻酸钠-果胶改性复合膜各项性能提高。以FTIR、SEM、XRD、接触角测定膜的表面结构形态和性质进行表征和测试。研究结果表明海藻酸钠-果胶复合膜各组分间的相容性好,经CaCl_2交联后显著改善膜的阻隔性能、机械性能及抗水性能,海藻酸钠-果胶改性复合膜是一种具有良好发展前景的可降解复合包装膜。     

可食性狭鳕鱼皮明胶-褐藻胶复合膜的性质与结构表征

采用狭鳕鱼皮明胶与褐藻胶共混法制备可食性复合膜,以改善鱼皮明胶膜的性能.结果表明:狭鳕鱼皮明胶具有很好的成膜性,但是其力学性能和热稳定性较低,阻水性差.褐藻胶与鱼皮明胶混合后,二者相容性较好,复合膜的透光卒达80%以上,力学性能增大,添加60%褐藻胶后,膜的抗拉强度和伸长率分别提高67.4%和112.6%,热变性温度提高8℃,水溶性和吸湿性都显著降低,说明复合膜的力学性能、热稳定性和阻水性都明显优于两种单一膜.红外光谱、X射线衍射和扫描电镜对其结构进行表征,表明两者通过化学结合生成了新的大分子化合物,得到稳定的复合膜.     

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。     

海藻酸钠/玉米醇溶蛋白抗菌复合膜的制备及其性能

以海藻酸钠作为基质,加入玉米醇溶蛋白共混制备食品复合包装膜,通过对其物理性能和机械性能的测定分析,从而得到复合膜的最佳海藻酸钠-玉米醇溶蛋白配比,并进一步制作并加入百里香精油抗菌包合物,最终制备具有缓慢释放抗菌物质的活性抗菌复合膜并对其表征和抗菌性能进行分析。结果显示,海藻酸钠与玉米醇溶蛋白成膜液质量比为1∶1时,复合膜具有最佳物理性能和机械性能,此时的复合膜水蒸气阻隔性能和透光率较好,抗拉强度达到最大3.75 MPa,断裂伸长率达到最大42.13%。百里香精油包和物添加量为制膜液总质量的0.2%时,抗菌复合膜的表面平整度和抗菌性有较好的综合效果,并且抗菌效果与百里香精油包合物添加量呈正向关,可以根据此趋势调整添加量,生产所需物化及抗菌性能的抗菌复合膜。     

Physical, mechanical, and barrier properties of carp and mammalian skin gelatin films

Films of 0.11 to 0.13 mm thickness were prepared using gelatins from the skins of cultured freshwater carp species and mammalian gelatins viz., porcine and bovine skin gelatin. A comparative study was made on the physical, mechanical, and barrier properties of these films. The amino acid composition, gel strength, clarity, and gel setting point of the gelatins were also determined. Carp skin gelatins had a lower imino acid content (19.16% to 20.86%) than mammalian skin gelatins (22.91% to 23.7%). Grass carp gelatin had gel strength of 230.2 B that is comparable to the reported value for bovine skin gelatin (227.2 B). The bloom values of rohu and common carp skin gelatins were 188.6 B and 181.3 B, respectively, which were significantly lower than mammalian gelatins. Mammalian gels have significantly higher (P < 0.05) setting temperatures (23.7 to 24.2 °C) than carp skin gelatins. Tensile strength (TS) was lowest for films from common carp and rohu skin gelatin (490 and 497 kg/cm(2), respectively) and highest for porcine skin gelatin film. The degree of transparency (L*) was significantly higher for films from grass carp, bovine hide, and pork skin gelatin films. Carp skin gelatin films had significantly lower water vapor permeability (WVP) and oxygen permeability (OP) than mammalian skin gelatin films, which indicated that carp skin gelatin based films have superior barrier properties than mammalian skin gelatin films.     

Characterization of edible film fabricated with channel catfish (Ictalurus punctatus) gelatin extract using selected pretreatment methods

ABSTRACT:  Farm-raised catfish are important to the economy of the southeastern states in the United States, and catfish processing produces about 55% of by-products for inexpensive sale. Therefore, the utilization of catfish by-products is of great interest to the catfish industry. The objectives of this research were to determine the optimum pretreatment method to extract catfish gelatin for edible film application, and to characterize physical, mechanical, and barrier properties of edible films fabricated with catfish skin gelatin. Catfish skins obtained from a local plant were treated with 6 selected pretreatment methods. The main extraction was performed with deionized water at 50 °C after pretreatment. The gelatin yield was calculated and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to characterize molecular weight (MW) profile. Color, tensile strength (TS), elongation, and water barrier property were determined to characterize the fabricated catfish gelatin films. From the results of gelatin yield, color, SDS-PAGE, as well as mechanical and barrier properties of the film, the pretreatment method with 0.25 M NaOH and 0.09 M acetic acid, followed by extraction at 50 °C for 3 h, was determined as the optimum extraction method. The catfish gelatin exhibited higher MW fractions than commercial mammalian gelatin. The catfish gelatin extracts possessed film-forming properties determined by TS, elongation, and water vapor permeability (WVP) comparable to those of commercial mammalian gelatin. The selected formula for catfish gelatin film was determined as 1% gelatin and 20% glycerol, resulting in greatest TS and lowest WVP.     

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 gelatin films prepared from under-utilized blue shark (Prionace glauca) skin

Gelatin film from blue shark (Prionace glauca) skin was investigated in order to utilize what is one of the most serious marine wastes in Japan. Film properties from shark skin such as tensile strength (TS), elongation at break (EAB) were evaluated. The TS of gelatin film from shark skin was affected by the protein concentration (1, 2 and 3%) of the film-forming solution (FFS). TS of the film from a 2% protein FFS was the highest. EAB and water vapor permeability (WVP) increased with increasing FFS protein concentration. WVP of shark skin gelatin was evidently low as compared to gelatin films from other fish. An increase in the FFS protein concentration decreased transparency at almost all wavelengths. Furthermore, opacity at 280 nm was characteristically high as compared to films from bony fish skin. The addition of glycerol improved flexibility and enhanced the UV barrier property at 280 nm. However, transparency at the visible range and WVP increased with increasing glycerol content.From the above, it was suggested that shark skin gelatin film technology can be applied to pharmaceutical products or rich-fat food due to its excellent water and UV barrier properties.     

Development and characterization of black mulberry (Morus nigra) pekmez (molasses) composite films based on alginate and pectin

Production of composite films is an important approach to improve functionality of edible films, by combining different polysaccharides, proteins, and lipids. Carbohydrate-based composite films are most attractive, which have good film-forming ability due to their unique colloidal properties. Fruit purees include high polysaccharide content that plays a role to have desirable film properties including mechanical resistance, efficient barrier properties, and selective permeability against oxygen transmission. The purpose of this study was to characterize physical, barrier, mechanical, thermal, and water sorption properties of composite films formulated with different mulberry pekmez concentrations (26, 32, and 38 °Brix) based on alginate or pectin. All film-forming solutions were showed shear thinning behavior with higher yield stress and viscosity-shear rate data were fitted to Ostwald de Waele model (R² ≥ 0.943). A noticeable decrease in tensile strength of films with increasing concentration was determined, but films prepared with high concentration showed more flexible. The mechanical properties of pectin films exhibited weakened properties compared to alginate films. Increasing pekmez concentration in the film matrix improved the water vapor permeability of alginate films, whereas pectin films showed reverse behavior as resulting in cracks and crack propagation within the structure. The sorption isotherms of films showed a typical profile of foods contain high soluble components and the Guggenheim–Anderson–deBoer (GAB) model gave a good fit for all of the obtained data. The results showed that mulberry pekmez films based alginate have a potential for food applications depends on the physical properties and for the replacement of non-biodegradable plastic packaging.     

Properties of Gelatin Film from Horse Mackerel (Trachurus japonicus) Scale

Optimal conditions for extracting gelatin and preparing gelatin film from horse mackerel scale, such as extraction temperature and time, as well as the protein concentration of film‐forming solutions were investigated. Yields of extracted gelatin at 70 °C, 80 °C, and 90 °C for 15 min to 3 h were 1.08% to 3.45%, depending on the extraction conditions. Among the various extraction times and temperatures, the film from gelatin extracted at 70 °C for 1 h showed the highest tensile strength and elongation at break. Horse mackerel scale gelatin film showed the greatly low water vapor permeability (WVP) compared with mammalian or fish gelatin films, maybe due to its containing a slightly higher level of hydrophobic amino acids (total 653 residues per 1000 residues) than that of mammalian, cold‐water fish and warm‐water fish gelatins. Gelatin films from different preparation conditions showed excellent UV barrier properties at wavelength of 200 nm, although the films were transparent at visible wavelength. As a consequence, it can be suggested that gelatin film from horse mackerel scale extracted at 70 °C for 1 h can be applied to food packaging material due to its lowest WVP value and excellent UV barrier properties.     

Mechanical and structural properties of rabbit skin gelatin films

In this article, the characteristics and structure of rabbit skin gelatin (RG) films were measured and compared with porcine skin gelatin (PG) films. The RG film was 8–10 μm thinner than that of PG film. RG films had better resistance to water and lower water solubility than did the PG film with the same gelatin and glycerol ratio due to the difference in their amino acid composition. The two types of gelatin films were almost transparent, which could give food a good appearance quality if these are used as packaging films. Both showed excellent barrier properties against UV light and could prevent the lipid oxidation reaction induced by ultraviolet light in the food system. The RG and PG films showed similar trends in mechanical properties as the change of their components. In general, the rigidity of the RG films was slightly lower than that of the PG films, but the flexibility was more prominent. This was due to intense interaction between gelatin molecules and glycerol molecules in RG films, but the dominant interaction was between the gelatin molecules in the PG films. The surfaces and cross-section microstructures of the RG and PG films were smooth and homogeneous, however for the RG films were more compact compared with the PG films.