脱乙酰基魔芋葡甘聚糖可食性膜材料研究

魔芋葡甘聚糖脱乙酰改性后成膜,与未改性膜相比,改性膜的强度、抗水性及耐洗刷性显著提高。用红外光谱、X-射线和扫描电镜分析了膜的结构,阐明了结构和功能的关系,并对改性膜作了常温涂膜保鲜实验,结果表明,改性膜对果蔬有一定保鲜作用。     

胶原膜糖基化产物的制备及表征

采用D-木糖通过美拉德反应对天然可食用胶原膜进行糖基化改性,得到一种新型天然可食用有色胶原膜。通过单因素实验考察了不同实验条件对反应程度的影响,并对改性后的胶原膜进行了相关表征。研究结果表明,当D-木糖浓度10%,pH 8.0时,胶原膜在60℃的水浴中反应14 h进行糖基化改性较适宜。红外光谱分析表明,糖基化改性没有破坏胶原的高级结构。差示量热扫描分析和热重分析显示,改性后胶原膜的变性温度提高了8.5℃,起始分解温度升高了约100℃,耐热性得到了显著的改善。接触角和吸水率测定表明,改性后胶原膜的亲水性有所提高。     

湿法糖基化改性玉米醇溶蛋白的物化特性以及在胶囊壳中的应用

利用麦芽糖浆对玉米醇溶蛋白进行湿法糖基化改性,以抗张强度为指标,考察改性后蛋白膜的机械性能,通过SDS-PAGE、DSC、傅里叶红外和扫描电子显微镜等手段考察蛋白改性前后的物化性质。结果表明：改性后蛋白膜较传统的明胶膜和纯玉米醇溶蛋白膜机械性能有较大提高。对SDS-PAGE电泳谱图分析可知玉米醇溶蛋白与麦芽糖浆进行了有效的糖基化接合。经傅里叶红外光谱扫描,可知改性后的玉米醇溶蛋白的化学结构发生了变化。差示量热扫描仪分析表明湿法改性的产物zein-MS膜热变性温度从由为改性前的188.47℃提高到了206.87℃,增加了膜的稳定性。扫描电子显微镜发现改性后膜的表面较改性前更加平整,孔洞基本消失。将玉米醇溶蛋白改性产物制成胶囊壳,以常规明胶胶囊壳作对照,参考《中华药典》（2015版）的相关检测指标进行检测,各项指标均合格。     

湿法糖基化改性玉米醇溶蛋白的物化特性及其在胶囊壳中的应用

利用麦芽糖浆对玉米醇溶蛋白进行湿法糖基化改性,以抗张强度为指标,考察改性后蛋白膜的机械性能,通过SDS-PAGE、DSC、傅里叶红外和扫描电子显微镜等手段考察蛋白改性前后的物化性质。结果表明:改性后蛋白膜较传统的明胶膜和纯玉米醇溶蛋白膜机械性能有较大提高。对SDS-PAGE电泳谱图分析可知玉米醇溶蛋白与麦芽糖浆进行了有效的糖基化接合。经傅里叶红外光谱扫描,可知改性后的玉米醇溶蛋白的化学结构发生了变化。差示量热扫描仪分析表明湿法改性的产物zein-MS膜热变性温度从由为改性前的188. 47℃提高到了206. 87℃,增加了膜的稳定性。扫描电子显微镜发现改性后膜的表面较改性前更加平整,孔洞基本消失。将玉米醇溶蛋白改性产物制成胶囊壳,以常规明胶胶囊壳作对照,参考《中华药典》(2015版)的相关检测指标进行检测,各项指标均合格。     

没食子酸对胶原蛋白膜的改性研究

采用没食子酸对胶原膜进行改性,考察了没食子酸溶液浓度、反应时间和pH对胶原膜机械性能的影响。首先,以抗张强度和断裂伸长率为评价指标,采用单因素和正交试验法优化得到没食子酸改性胶原膜的最佳反应条件为:没食子酸浓度5 g/L、pH值6和反应时间4 h。然后,通过红外光谱、机械强度、耐热性、抗水性和抗氧化性测试,表征并比较了胶原膜改性前后的结构和性能变化。结果表明,没食子酸改性后胶原的三股螺旋结构未被破坏;改性胶原膜的抗张强度提高了16.1%,热变性温度提高了12.4%,吸水率降低了15.1%,并且胶原膜的超氧自由基和羟基自由基清除能力均大大提高,表现出更优的抗氧化性。     

谷氨酰胺转移酶改性对花生蛋白膜性能的影响

采用谷氨酰胺转移酶对花生蛋白进行改性制备花生蛋白膜以提高膜的性能,研究了谷氨酰胺转移酶对花生蛋白膜性能、微观结构、差示扫描热量以及红外光谱的影响。与对照相比,改性花生蛋白膜的拉伸强度、断裂伸长率和阻氧性分别提高了91.69%、53.69%和4.97%;水溶性和水蒸气透过率分别降低了15.12%和了32.85%。改性后,花生蛋白膜的内部孔洞变小,结构更加致密,但热稳定性下降。研究同时表明,谷氨酰胺转移酶主要作用于花生蛋白分子中的羟基及胺基,通过交联作用形成了酰胺基团,并改变了花生蛋白分子原有的二级结构。     

交联改性对敷料用壳聚糖/聚氧化乙烯纳米纤维膜性能的影响

为改善壳聚糖基纳米纤维膜的耐水性和结构稳定性,对静电纺丝制得的壳聚糖/聚氧化乙烯(PEO)纳米纤维膜进行戊二醛交联改性,研究不同交联时间下纳米纤维膜在模拟人体缓冲液中微观形态结构、化学结构和结晶结构的变化,并对交联后纤维膜的耐水性和力学性能进行表征。结果表明:壳聚糖基纳米纤维膜经戊二醛交联处理后,在缓冲液中浸泡24 h纤维形态的稳定性得到明显改善,且随着交联时间的增加,纤维膜在缓冲液中的吸水率逐渐增加,溶失率逐渐降低;交联改性改变了壳聚糖大分子固有的结晶结构,使纤维膜的初始模量提高,力学强度随交联时间的增加先增加后降低。     

抗菌肽改性蚕丝蛋白膜的细胞相容性研究

通过化学改性的方法制备一种抗菌肽接枝蚕丝蛋白(丝素)膜,利用红外光谱、抗菌性能测试等手段对其结构和抗菌活性进行了分析,进一步研究了该改性蚕丝蛋白膜对小鼠成纤细胞L929的细胞相容性。结果表明,改性蚕丝蛋白膜具有水不溶性的β-折叠片层结构和良好的抗菌性能;小鼠成纤细胞在膜表面能正常黏附和生长,说明该改性蚕丝蛋白膜无显著细胞毒性。     

柠檬酸改性聚乙烯醇淀粉复合膜的结构及性能研究

为了改善聚乙烯醇淀粉膜的抗菌性能,采用流延法制备了不同质量分数的柠檬酸改性聚乙烯醇淀粉复合膜,通过XRD、FTIR、SEM等方法分析测试了复合膜的微观组织结构及性能。结果表明,添加柠檬酸并未改变复合膜的晶型结构,当柠檬酸含量在4%以上时膜层晶态衍射峰的强度显著增强。改性后的复合膜具有更加均匀平整的表面状态,同时膜层的断面结构也更加致密规则。随着柠檬酸含量的增加,复合膜含水率和水蒸汽透过率减小;复合膜拉伸强度减小而断裂伸长率增加。柠檬酸改性对复合膜透光率的影响较小,但复合膜雾度增加。改性后的复合膜对大肠杆菌具有良好的抑菌性能。添加量为6%柠檬酸改性复合膜具有最佳的综合性能。     

低温等离子体对PTFE微孔膜结构和性能的影响

聚四氟乙烯PTFE微孔膜的表面能较低,粘结性和润湿性较弱,为了改善这种状况,使PTFE微孔膜能与其它材料更好地复合。本文采用低温等离子体对PTFE微孔膜进行改性,重点研究了低温等离子体的改性处理工艺参数,包括辐射距离、射频功率、处理时间和气体流通量对膜性能(接触角和失重率)的影响。并用傅里叶变换红外光谱(ATR-FTIR)、x射线光电子能谱(XPS)、扫描电镜(SEM)和拉力测试进行表征,结果表明,低温等离子体不同的工艺参数处理对PTFE微孔膜的结构和性能影响很大。改性后的PTFE微孔膜,拉伸强度得到了进一步的提升,亲水性也增强,并且表现出良好的力学性能,改性后的膜材料应用更加广泛。     

Influence of konjac glucomannan on thermal and microscopic properties of frozen wheat gluten,glutenin and gliadin

The effects of different konjac glucomannan (KGM) concentrations (0.5%, 1.5%, 2.5%, 3.5%, 4.5%, w/w) on the thermal and microscopic properties of the frozen wheat gluten, glutenin and gliadin were investigated in this study. KGM exerted a positive effect on the denaturation temperature and denaturation enthalpy of frozen gluten and gliadin, while KGM decreased those of frozen glutenin. Such effects induced by KGM were resulted from the interaction between KGM and frozen wheat gluten, glutenin and gliadin. The underlying mechanism was discussed from the perspective of protein structure. Specifically, the addition of KGM increased the α-helix structure of frozen gluten and gliadin, while decreased the α-helix of frozen glutenin. Furthermore, β-turn of frozen gluten and gliadin presented a decreasing trend with increasing amount of KGM. Scanning electron microscopy confirmed that there was stronger interaction between wheat protein and KGM. These results provide fundamental knowledge for better application of KGM in frozen protein-based foods.     

添加魔芋葡甘聚糖对鸡蛋干品质的影响

以全蛋液和魔芋葡甘聚糖(konjac glucomannan,KGM)为原料制作鸡蛋干,研究了KGM添加量对鸡蛋干的硬度、弹性、出品率、保水性、色泽、消化特性及感官品质的影响。结果表明:随着KGM添加量的增大,鸡蛋干的硬度先增大后降低,当KGM添加量为0.16%时,鸡蛋干的硬度最大。样品的出品率和保水性随着KGM添加量的增加先增大后降低,当KGM的添加量为0.12%时,样品出品率和保水性最大。KGM的添加使样品的色泽由深变浅但不显著,同时降低了蛋白质的消化率;添加了KGM的样品发酵液中挥发性成分与蛋白组(发酵液+1%胰蛋白胨)有一定差别且同类的含量相差较大。综合各个感官指标及整体接受性得出,当KGM添加量为0.12%时,样品感官食用品质最好。     

Physicochemical properties of konjac glucomannan extracted from konjac flour by a simple centrifugation process

Konjac flour (KF) contains main polysaccharide, konjac glucomannan (KGM) that is applied in various applications; however, extraction of KGM is complicated. A simple centrifugation process was used to extract KGM from KF and the influence of extraction temperatures on its physicochemical properties was determined. The centrifugation process was effective for the extraction of KGM and the results revealed two effective temperatures (35 °C and 75 °C). The extracted KGM was easy to grind. Ash and protein contents of the extracted KGM were clearly reduced, however the ash and protein contents of the KGM extracted at the high temperature (75 °C) were significantly lower than that extracted at the low temperature (35 °C), and thus proofs the extraction at the high temperature to be more effective. Furthermore, improved purities in both extracted glucomannan samples were attained in comparison to commercial KGM. While the yield percentages of the samples differed, no significant disparity in morphology and particle size was determined. Particles of both extracted KGM were comparable in shape and size. Moreover, the transparency of both extracted KGM solutions was higher than commercial KGM solution. These results suggested that the extraction temperature at 75 °C is effective in extraction KGM from KF.     

影响魔芋葡甘聚糖吸附香兰素的因素研究

为探讨魔芋葡甘聚糖吸附香兰素的基本特征,以魔芋葡甘聚糖溶液浓度、pH值、温度和时间为试验因素,进行单因素试验,对结果进行方差分析。结果表明,随着魔芋葡甘聚糖浓度增大,香兰素吸附量呈增大趋势;随pH值升高,吸附量增加;温度越高,吸附量越低;随时间的延长,吸附量逐渐减少;魔芋葡甘聚糖吸附香兰素的工艺条件为：合适的魔芋葡甘聚糖与香兰素配比,魔芋葡甘聚糖溶液pH=9．0-11．0,常温下吸附,吸附时间10min。     

魔芋葡甘聚糖可食性膜材料研究(Ⅱ)

将魔芋葡甘聚糖与黄原胶共混后成膜,与未改性膜相比,共混后的膜显示了较好的强度和抗水性。用Ｘ－射线衍射和扫描电镜分析了膜的结构,阐明了结构和功能的关系。     

Preparation and characterization of konjac glucomannan microcrystals through acid hydrolysis

Konjac glucomannan (KGM) was treated by a facile acid hydrolysis to fabricate KGM microcrystals. At the first day of hydrolysis, KGM microcrystals were formed. With the extension of hydrolysis time, the particle size of KGM microcrystals decreased from 45 μm to 15 μm. In addition, compared with native KGM, the morphological, physicochemical, crystalline, and thermal properties of KGM microcrystals changed significantly. SEM images showed the irregular shapes and rough surfaces of KGM microcrystals as well as the smooth surface of native KGM. FTIR measurements revealed the cleavage of carbonyl groups in KGM microcrystals. XRD curves clearly presented the crystalline structure of KGM microcrystals, and the relative crystallinity increased to approximately 50%. DSC analysis showed that microcrystals had a better thermal stability than native KGM, which could be preferably used as reinforcement in the biocompatible material at high temperature.     

魔芋葡甘露聚糖没食子酸酯化改性的研究

用乙酰化的没食子酸对魔芋葡甘露聚糖进行酯化改性,并对改性产物性能进行了表征。结果表明,当反应底物魔芋葡甘露聚糖与三乙酰没食子酰氯的质量比为1:3.6时,改性产物的酯化度高达0.6281。与未改性的魔芋葡甘露聚糖相比,改性魔芋葡甘露聚糖的粘度、稳定性、冻融稳定性均发生不同程度的改变。醋酸钠法对改性产物的乙酰保护基具有一定的脱除效果,其得率约71.5%。研究结果可为魔芋葡甘露聚糖的改性和精细化利用提供参考数据。     

Modification of the microstructural and physical properties of konjac glucomannan-based films by alkali and sodium carboxymethylcellulose

Edible films were cast from konjac glucomannan (KGM) solutions, with or without added alkali (KOH) and/or sodium carboxymethylcellulose (CMC). Four types of KGM-based films (KGM, KGM–KOH, KGM–CMC and KGM–CMC–KOH) were produced and characterized by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), moisture sorption, water vapour permeability (WVP), and tensile tests. Tensile properties were studied as a function of water activity (a_w) over the range from 0.22 to 0.84. SEM revealed that films, with and without KOH, exhibited cross-sectional lamellar structures running perpendicular and parallel, respectively, to the film surface. Alkali treatment produced films with enhanced crystallinity, lower water-sorptive capacity (WSC) and WVP, and higher tensile properties. These effects were attributed to alkaline deacetylation of KGM molecules which permitted greater intermolecular interactions. The presence of CMC appeared to suppress crystallinity of native KGM films, but enhanced that of deacetylated KGM films. Films incorporating CMC exhibited higher WSC and WVP, but variable tensile properties depending on alkali treatment and a_w. The tensile properties of all KGM-based films were profoundly affected by a_w. Tensile modulus (TM) of all films were antiplasticized as a_w was increased from 0.22 to 0.43, but tensile strength (TS) was generally plasticized by water. Tensile elongation of KGM, KGM–KOH, and KGM–CMC–KOH films was generally much less sensitive to water. However, KGM–CMC films exhibited minimum elongation, attributed to antiplasticization by water, over the intermediate a_w range from 0.43 to 0.69. KGM–CMC–KOH films exhibited the highest TM and TS at any particular a_w.     

魔芋葡甘聚糖与可得然胶的相互作用

通过分子动力学模拟魔芋葡甘聚糖（konjac glucomannan,KGM）和可得然胶分子的作用方式;采用旋转流变仪测定25 ℃条件下KGM/可得然胶溶胶黏度、剪切力随剪切速率变化的规律;采用透射电子显微镜和原子力显微镜观察KGM/可得然胶共混溶胶在90 ℃条件下的分子形貌。分子模拟表明KGM和可得然胶分子间存在氢键相互作用;KGM/可得然胶流变性结果表明二者分子间存在相互作用,且共混溶胶剪切力协同指数由1.43提高到1.97,两种多糖分子共混具有协同-增黏作用,可能是两种多糖分子相互作用的结果;显微镜观察结果表明分子间可形成互穿网状结构（可能由氢键相互作用驱动）,进一步从分子水平上验证KGM和可得然胶存在相互作用以及两者的作用方式。     

An investigation into the application of konjac glucomannan as a flavor encapsulant

The application of konjac glucomannan (KGM) in flavor encapsulation in the spray-dry method was investigated in this paper using sweet orange oil as the model. KGM provided the highest encapsulation yield when the apparent viscosity of the KGM solution was reduced to 200 mPa S by cellulase hydrolysis. In the presence of emulsifier Tween 80, the hydrolyzed KGM offered comparable encapsulation yield with Arabic gum and starch sodium octenyl succinate (SSOS), but provided significantly higher encapsulation yield than maltodextrin. Besides, the combination of KGM with Arabic gum, SSOS, and maltodextrin, were also studied. The combination could significantly (P < 0.05) increase the encapsulation yield in the KGM content up to 80% compared with pure KGM; when the KGM content was reduced to 20%, the combination with maltodextrin resulted in a significant (P < 0.05) decrease in encapsulation yield, possibly due to the poor emulsifying capability of both KGM and maltodextrin. The effect of encapsulation on flavor composition was investigated by using the fingerprint technique and the vectorial angle method was adopted to assess the similarity between the chromatographs. The comparison showed that KGM had similar flavor retention with SSOS and Arabic gum, but provided a significant (P < 0.05) higher retention than maltodextrin. The encapsulated flavors exhibited few pores and smooth surface under TEM with the size ranging from 5 to 15 μm. It was concluded that KGM provided comparable flavor retention capability as the most widely used Arabic gum and SSOS and had great potential as a flavor encapsulant.