改性纳米SiOx复合涂膜在莲藕保鲜中应用

以壳聚糖、海藻酸钠、改性纳米SiOx为涂膜材料,按照L9(34)正交试验制备不同配比的改性纳米SiOx复合涂膜。结果表明,复合保鲜膜的最佳配比为1.50%壳聚糖、0.60%海藻酸钠、0.02%改性纳米SiOx时可有效保持莲藕水分,抑制莲藕褐变,提高贮藏期间产品品质,延长货架期。     

改性壳聚糖的研究及其在金秋梨保鲜中的应用

采用纳米SiOx对壳聚糖进行改性得到复合涂膜,考察水蒸汽透过率、氧气透过率及抑菌性等指标.用改性后的壳聚糖对果蔬涂膜保鲜,并测试室温下的VC含量、保鲜时间和好果率.结果表明:壳聚糖纳米SiOx复合膜(CTS-SiOx)与壳聚糖单膜(CTS)相比,其水蒸气透过率下降35%、氧气透过率下降21%,复合涂膜抗菌效果明显,室温下果蔬保鲜时间得到明显延长,其中金秋梨由20d延长至60d,好果率为80%.     

改性壳聚糖保鲜涂膜透水率的研究

利用纳米SiOx对壳聚糖涂膜进行改性,采用三因素二次旋转组合正交设计研究了壳聚糖、纳米SiOx和单甘酯等因素对壳聚糖保鲜膜透水率的影响,得到相应单指标二次回归模型。结果表明：当壳聚糖用量1.547 g、SiOx用量0.028 g、单甘酯用量0.015 g时,具有较低的透水率,膜的综合性能最好,室温下果蔬保鲜时间明显延长。     

壳聚糖及其与纳米SiO_x复合涂膜对莲藕贮藏品质的影响

配制了壳聚糖、壳聚糖/纳米SiOx和壳聚糖/纳米SiOx/氯化亚锡3种涂膜液,对莲藕进行了涂膜,以不涂膜莲藕为对照,置于0～10℃贮藏,通过测定失重率、呼吸强度、L值、PPO活性、可溶性糖质量分数及硬度,研究了壳聚糖及其复合膜对莲藕贮藏保鲜过程中品质的影响.结果表明:壳聚糖/纳米SiOx组效果最好,有效地抑制了莲藕采后呼吸、失重、糖物质消耗、PPO活性升高、颜色变暗及硬度下降,而壳聚糖/纳米SiOx膜中添加氯化亚锡并不能对莲藕保鲜效果起到更好的作用.     

改性SiOx/WPU涂膜对腐败希瓦氏菌生物被膜的抑制作用

为获得对水产品中腐败希瓦氏菌生物被膜具有优良抑制性能的水性聚氨酯(WPU)涂膜，以不同微观形貌的SiOx微纳米粒子为粗糙度构建因子，采用滴涂法制备SiOx/WPU涂膜，测定改性SiOx/WPU涂膜表面的疏水疏油性能、表面能、微观形貌和热稳定性能，揭示改性SiOx/WPU涂膜对腐败希瓦氏菌生物被膜的抑制机制。结果表明，以十六烷基三甲基溴化铵(CTAB)改性的SiOx颗粒为粗糙度构建因子制备的C-SiOx/WPU涂膜，尽管表面氟含量最高，但其水和正十六烷接触角分别为139.0°±3.5°和0°，仅表现为疏水超亲油性，热稳定性和抗细菌黏附性最差；改性气相纳米SiOx/WPU涂膜表现为超疏水超亲油性，热稳定性最好，且可以抑制腐败希瓦氏菌的初期黏附；以改进的St?觟ber法在同一溶剂体系中制备和改性SiOx微纳米粒子为粗糙度构建因子制备的改性微米级SiOx/WPU涂膜为超双疏表面，热稳定性较高，对腐败希瓦氏菌不可逆黏附的抑制最好，可有效降低生物被膜的代谢活性，减少胞外多糖(EPS)的分泌，培养24 h后其表面刚开始形成微菌落。本研究的超双疏性改性微米级SiOx/WPU涂膜可用于制备食品包装材料，为抗生物被膜材料在食品包装领域的应用提供技术支持。     

壳聚糖/纳米SiOx/单甘酯复合涂膜对黄瓜保鲜的研究

采用壳聚糖、纳米SiOx及单甘酯作为复合涂膜剂,通过正交实验优化涂膜配方,对黄瓜进行涂膜处理,室温下对黄瓜进行失水率、硬度、叶绿素含量和Vc含量的测定,并且对复合涂膜的物理性能和抗菌性能进行测定。结果表明:壳聚糖1%、纳米SiOx1.5%、单甘酯0.4%为最佳配比,可有效延长黄瓜的货价保藏期,并且该复合涂膜在物理性能和抗菌性能上都较纯壳聚糖膜有一定程度上的改善。     

壳聚糖浓度对原位合成纳米SiOx壳聚糖涂膜性能的影响

在不同壳聚糖浓度条件下制备原位合成纳米SiOx壳聚糖涂膜,对其进行XRD、FT-IR、SEM、TEM表征分析,研究壳聚糖浓度对复合涂膜透气性、力学性能及其保鲜性能的影响。研究结果表明,涂膜的微观结构与壳聚糖浓度有关。原位合成的纳米SiOx与壳聚糖间形成化学键力的结合,当壳聚糖质量浓度为1.5 g/100 mL时,壳聚糖流延成膜失水均匀,原位合成的纳米SiOx粒子多为8～15 nm的颗粒,呈链状链接,基本无团聚,分散状态良好,涂膜均匀、致密,其断面的大孔隙结构减少,基本无小裂纹。随着壳聚糖浓度的增加,涂膜的水蒸气透过率、透CO_2性和透O_2性均降低,同时其拉伸强度提高,断裂伸长率下降。在4℃条件下用不同浓度的壳聚糖涂膜,对美国红鱼的保鲜试验结果表明,随着贮藏时间的延长,美国红鱼的鲜度指标下降。壳聚糖涂膜延缓了美国红鱼的品质下降,其中,壳聚糖质量浓度为1.5 g/mL时,其保鲜性能最优。     

纳米硅基氧化物（SiOx）保鲜果蜡研究与开发

本文对国内外果蔬涂膜保鲜剂——果蜡的生产和应用现状进行了分析，并对纳米硅基氧化物（SiOx）保鲜果蜡研制、工艺配方研究、成膜材料的优选与配比试验、纳米SiOx材料的利用与成膜剂的改性等关键技术、保鲜性能试验和新产品开发等做了详细的介绍。     

纳米镁化合物对壳聚糖复合涂膜性能的影响

以纳米镁化合物改性壳聚糖涂膜,不仅能改善涂膜的力学性能和透气性能,还可增强其抗菌性能。以纳米镁化合物作为壳聚糖改性材料的涂膜研究,国内外鲜见报道。为探讨镁化合物纳米粉体对壳聚糖涂膜性能的影响,测定了不同形貌纳米镁化合物粉体添加改性后壳聚糖涂膜的性能指标,并对这种壳聚糖涂膜进行SEM、XRD及FT-IR表征。结果表明,镁化合物纳米粉体表面的活性基团与壳聚糖作用,导致壳聚糖的FormⅠ晶型减少,FormⅡ晶型发生改变。添加Mg_2(OH)_3Cl纳米片和纳米MgO颗粒后,壳聚糖复合涂膜的力学性能增强,透湿性能减弱;然而由于MgO纳米棒和MgO纳米小球在涂膜中存在团聚现象,所以导致壳聚糖与纳米粉体不能很好结合,涂膜内产生空隙甚至裂缝,涂膜机械性能下降及透湿性能增强。添加纳米MgO颗粒对壳聚糖涂膜的透O_2性、透CO_2性改良效果最佳。镁化合物纳米粉体对壳聚糖涂膜的光学性能影响不显著,说明添加镁化合物纳米粉体不影响涂膜在食品保鲜中的应用。     

壳聚糖/纳米SiOx复合保鲜膜性能衰减的研究

为了研究壳聚糖/纳米SiOx(CTSS)复合保鲜剂性能的衰减,采用流延法制备研究壳聚糖/纳米SiOx复合膜,并分别放置于4、14、24、34、44℃恒温环境中24 h,测定其pH值、氧气透过系数(OP)、二氧化碳透过系数(CP)和水蒸气透过系数(WVP)以及对青霉、酵母菌的抑菌性;同时,在4℃条件下,用CTSS和CTS分别涂膜处理草莓,并测定草莓腐烂率。结果表明:低温4℃贮藏10 d后,CTSS膜处理的草莓比CTS膜组腐烂指数降低了21.4%;纳米SiOx/壳聚糖复合膜随着放置温度的提高,pH值上升;复合膜OP、CP和WVP增大,44℃比4℃的OP、CP和WVP分别增加了13.02、27.54、25.56 mg/cm2·d;对酵母、青霉的抗菌性能减弱;壳聚糖/纳米SiOx复合膜对气体分子的通透阻力减小,从而导致壳聚糖/纳米SiOx复合保鲜剂性能降低。     

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.     

Effects of ultraviolet-C irradiation on the physicochemical properties of polysaccharide films prepared from the stalk base of oyster mushrooms (Pleurotus ostreatus)

The effects of ultraviolet (UV)-C irradiation on the physicochemical properties of oyster mushroom polysaccharide (OMP) films were investigated. The prepared OMP films were subjected to UV-C treatment (5.4 kJ m⁻²). UV-C irradiation increased the tensile strength and decreased the water vapour permeability of the OMP films. In addition, the incorporation of 1.0% Cudrania tricuspidata leaf extract (CTLE) enhanced the antioxidant activity as well as antimicrobial activity of OMP films; however, UV-C treatment did not affect the activities of films containing CTLE. Furthermore, UV-C-irradiated films had higher contact angles than non-irradiated films, indicating increased surface hydrophobicity. Microstructural imaging revealed that UV-C treatment caused the surface of treated films to be smoother than that of untreated films owing to surface degradation. These results indicated that UV-C irradiation can be used for OMP films to improve film properties that are associated with application of films as food packaging material.     

2种淀粉-壳聚糖-纤维素衍生物可食膜特性的对比

研究了2种不同纤维素衍生物对淀粉-壳聚糖可食膜性能的影响,并通过X射线衍射法、扫描电镜、热重分析对可食膜结构进行表征。结果表明:加入羧甲基纤维素钠使可食膜的抗拉强度下降,而伸长率却明显增大;加入甲基纤维素使可食膜的抗拉强度显著增大,而伸长率的变化并不大。2种可食膜对金黄色葡萄球菌和大肠杆菌都有明显的抗菌性,而且对前者的抗菌性明显优于后者。X射线衍射及热重分析结果表明可食膜中纤维素衍生物与淀粉、壳聚糖有较强的相互作用。     

磁控溅射纳米纤维基银膜的结构和性能

在室温条件下采用直流磁控溅射方法,在醋酸纤维素(CA)纳米纤维表面沉积纳米银(Ag)薄膜,采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对不同溅射功率的纳米银膜的形貌和微结构进行表征;利用X射线衍射分析了纳米银膜的结晶状态;同时研究了在不同溅射功率条件下制备的沉积纳米Ag膜复合纳米纤维的光学透射性能。实验结果表明：纳米结构银薄膜由极其微小的均匀性较好的粒子组成,随着溅射功率的增加,组成纳米Ag薄膜的Ag粒子尺寸增大,薄膜的致密性和均匀性增加;制备的Ag薄膜均呈面心立方的多晶结构,并且结晶性能随着溅射功率的增加而逐渐增加,抗紫外线透射能力明显增强。     

Properties of Films Produced by Cross-linking Whey Proteins and 11S Globulin Using Transglutaminase

Transglutaminase (TG) was used to produce films from whey protein isolate, soybean 11S globulin and a mixture of the two (1:1, wt/wt). Solubility of TG cross-linked films was lower than that of control films at pH 3, 4, 6 and 8. Solubility of control films in 6.6M urea and in 10% SDS was higher than that of TG cross-linked films. Hydrolysis of control and TG cross-linked films by trypsin and α-chymotrypsin was similar after 24h incubation. Mean thickness of films ranged from 69 to 77 μm and there were no differences among thicknesses. Average tensile strength values of TG cross-linked films were two times greater than those of the homologous controls.     

Antimicrobial Films Based on Na-alginate and κ-carrageenan

Na-alginate- and κ-carrageenan-based antimicrobial films were prepared, to examine their antimicrobial effect and mechanical properties. Antimicrobial agents: lysozyme, nisin, grape fruit seed extract (GFSE) and ethylenediaminetetraacetic acid (EDTA) were incorporated into films, both alone and in combination. Na-alginate-based films exhibited larger inhibitory zones compared to κ-carrageenan-based films even within similar combinations and levels of antimicrobial agents. GFSE-EDTA in both Na-alginate- and κ-carrageenan-based films showed inhibitory effect against all indicator microorganisms. Tensile strength (TS) values were weaker and elongations (E) before breakage less frequent for films with antimicrobial compounds compared to that of films without the antimicrobial compounds.     

Mechanical Properties of Heat-cured Whey Protein-based Edible Films Compared with Collagen Casings under Sausage Manufacturing Conditions

ABSTRACT: Edible films were produced using whey protein isolate (WPI) (5%, w/v), glycerol (3.3%, w/v) and candelilla wax (0.8%, w/v). One set of films was heat cured at 90°C for 12 h and another at 80°C for 24 h. WPI-based films, together with collagen films, were put through a meat-processing scheme typical of Polish sausage manufacture. Meat-processing conditions were stage 1: 57°C/60 min/36% RH; stage 2: 65°C/90 min/60% RH; and stage 3: 77°C/30 min/80% RH. Effects of meat-processing conditions on mechanical properties: tensile strength (TS), elongation (%E), and apparent modulus (AM) were determined. All films remained intact throughout the process. TS, %E, and AM of collagen films did not change during the multistage cooking process. The %E of heat-cured WPI films was similar to that of collagen films and also did not change during the cooking stages. The TS and AM of both heat-cured WPI-based films were initially lower than collagen films and continued to decline during the cooking stages. TS and AM of both films at the end of cooking were lower ( P < 0.05) than films that did not go through the multistage cooking process.     

Development of Antioxidant Packaging Material by Applying Corn‐Zein to LLDPE Film in Combination with Phenolic Compounds

Abstract: Functional active packaging materials were successfully developed by incorporating antioxidant agents into corn‐zein‐laminated linear low‐density polyethylene (LLDPE) film. The minimum effective concentrations of the active compounds (for example, thymol, carvacrol, eugenol) were determined and these compounds were then laminated into LLDPE films to develop corn‐zein‐laminated films with antioxidant agents. The release rate of antioxidant agents in gas and liquid media were determined along with the mechanical and water barrier properties of the films containing these compounds. Tensile strength and percentage elongation at break were reduced in the corn‐zein‐laminated LLDPE films when compared to typical LLDPE film. Furthermore, the ability of the corn‐zein‐laminated films to repel moisture decreased by approximately 12.2%, but was improved by incorporating hydrophobic antioxidant compounds in the corn‐zein layer. Examination of release kinetics in the gas and liquid phases verified that antioxidants were effectively released from the films and inhibited oxidation during testing. Finally, the films were used for fresh ground beef packaging, and effectively inhibited lipid oxidation and had a positive effect on the color stability of beef patties during storage. These results indicate that the developed antioxidant films are a novel active packaging material that can be effectively implemented by the food industry to improve the quality and safety of foods. Practical Application: Zein protein, a by‐product of corn processing industry, was laminated into plastic films in combination with natural phenolic compounds to develop antioxidant packaging films. The films demonstrated their efficient release patterns of antioxidant compounds, which are suitable for packaging applications and food protection.     

Plasticization of Pea Starch Films with Monosaccharides and Polyols

ABSTRACT:  Monosaccharides have several hydroxyl groups and a compatible structure with starch polymers resulting in effective plasticization in starch films. Two groups of plasticizers (polyols and monosaccharides) were used to compare their plasticizing efficiency. Fructose, glucose, mannose, galactose, glycerol, sorbitol, ethylene glycol, and maltitol were selected at 13.031 mmol per 100 g of pea starch. Edible starch films were produced after heat gelatinization and dehydration of the 3% starch dispersion. The microstructure, attenuated total reflection foorier transform infrared (ATR-FTIR) characteristics, thickness, moisture content, tensile strength, modulus of elasticity, elongation-at-break, water vapor permeability, and transparency of films were determined. Microstructure of the film solutions showed that some swollen starch granules and their remnants existed in the film. Compared to the FTIR spectra of pure starch films, the spectra of plasticized films showed that more hydrogens bound hydroxyl groups and more water molecules were attracted around starch polymer chains. Ethers were produced in glycerol-plasticized films. Monosaccharide-plasticized films were comparable to the polyol-plasticized films in tensile test, but more resistant in moisture permeation than the polyol-plasticized films. It was assumed that the structural compatibility of monosaccharides with starch might result in denser polymer-plasticizer complex, smaller size of free volume, and less segmental motions of starch chains. In conclusion, monosaccharides were identified as effective plasticizers for starch film.     

Physical Properties of Whey Protein–Hydroxypropylmethylcellulose Blend Edible Films

ABSTRACT: The formations of glycerol (Gly)‐plasticized whey protein isolate (WPI)–hydroxypropylmethylcellulose (HPMC) films, blended using different combinations and at different conditions, were investigated. The resulting WPI: Gly‐HPMC films were analyzed for mechanical properties, oxygen permeability (OP), and water solubility. Differences due to HPMC quantity and blend method were determined via SAS software. While WPI: Gly and HPMC films were transparent, blend films were translucent, indicating some degree of immiscibility and/or WPI–HPMC aggregated domains in the blend films. WPI: Gly‐HPMC films were stronger than WPI: Gly films and more flexible and stretchable than HPMC films, with films becoming stiffer, stronger, and less stretchable as the concentration of HPMC increased. However, WPI: Gly‐HPMC blended films maintained the same low OP of WPI: Gly films, significantly lower than the OP of HPMC films. Comparison of mechanical properties and OP of films made by heat‐denaturing WPI before and after blending with HPMC did not indicate any difference in degree of cross‐linking between the methods, while solubility data indicated otherwise. Overall, while adding HPMC to WPI: Gly films had a large effect on the flexibility, strength, stretchability, and water solubility of the film polymeric network, results indicated that HPMC had no effect on OP through the polymer network. WPI–HPMC blend films had a desirable combination of mechanical and oxygen barrier properties, reflecting the combination of hydrogen‐bonding, hydrophobic interactions, and disulfide bond cross‐linking in the blended polymer network.