纳米金应用于蛋白质纤维染色的研究

概述了纳米金粒径的大小不同表现出不同的颜色的特性．以及金及纳米金的安全可靠性,采用柠檬酸钠还原氯金酸制备了纳米金,利用紫外可见分光光度计和透射电子显微镜对纳米金进行了表征。制备的纳米金溶胶应用于对羊绒、羊毛纤维及羊毛织物进行染色。探讨了纳米金与蛋白质的作用原理,并对其作用条件：颗粒大小、pH、表面活性剂、修饰剂、有机溶...     

胶体金制备技术的改进与优化

采用柠檬酸三钠法、抗坏血酸还原法、柠檬酸三钠-鞣酸法3种方法制备胶体金,探索最优的制备方法。考察不同制备方法对胶体金外观颜色、颗粒大小以及均一性的影响。结果表明:采用0.22μm滤膜过滤的胶体金均一性较好,以100 m L 0.01%的四氯金酸溶液中2 m L 1%柠檬酸钠最佳的添加量的柠檬酸三钠法为制备胶体金最合适的方法。     

纳米硒-壳聚糖复合物缓释作用研究

以盐酸羟胺、亚硒酸为反应物,食品级海藻酸钠为软模板,制备了分散性良好的红色无定形纳米硒。辅以壳聚糖、玉米淀粉,合成出了纳米硒-壳聚糖复合颗粒,在模拟消化液中研究了复合物的硒缓释行为,考察了模拟消化液pOH、缓释温度、缓释时间对硒释放率的影响。结果表明,含硒复合物适合于缓释,最佳缓释条件为:模拟消化液pOH=12.80,缓释温度38℃,缓释2.8h,纳米硒-壳聚糖复合物的硒释放率达到68.43%,实测结果与模型预测值的相对误差仅为0.48%。     

柠檬醛微胶囊的制备及吸水性对微胶囊结构性能的影响

以壳聚糖、海藻酸钠、氯化钙为复合壁材,采用复凝聚法制备了柠檬醛微胶囊,研究了壳聚糖、氯化钙、海藻酸钠用量对微胶囊含油量、粒径以及孔径和比表面积的影响,确定了柠檬醛微胶囊的最佳制备条件,并测试了其缓释性能。柠檬醛微胶囊的最佳制备工艺条件为:在壳聚糖1.2011 g/50 mL H_2O、海藻酸钠3 g/100 mL H_2O、氯化钙1.5 g/50 mL H_2O、精油1 mL时,柠檬醛含量为2.18%。以CoCl_2为指示剂,在相同条件下制备了CoCl_2指示剂微胶囊,研究了指示剂微胶囊的吸水性能对颜色、微胶囊的粒径、表观形貌的影响,建立了微胶囊的吸水量与颜色间的定量关系。研究结果为宏观简便观测分析柠檬醛微胶囊品质奠定了初步理论依据。     

胶体金免疫层析技术在食品检测中的运用

正胶体金是由氯金酸在还原剂如柠檬酸三钠、抗坏血酸、柠檬酸钠、鞣酸等作用下聚合成一定大小的金颗粒,并在静电作用下形成稳定的胶体状态。因为胶体金具有肉眼可见的红色,当抗原与抗体结合部位的金颗粒达到一定数量时,便可观察到红色条带,通过红色条带即可判断检测结果。本文将对胶体金免疫层析技术在食品检测中的运用展开研究,以期能够为关注这一领域的人们提供相关有价值的参考。胶体金免疫层析技术分析     

金纳米棒比色探针法测定维生素C的初步研究

目的采用金纳米棒作为探针,构建一套灵敏简单的用于检测维生素C的比色方法。方法采用壳聚糖-三聚磷酸钠复合物作为还原剂和稳定剂制备金纳米棒;采用紫外-可见光分光光度计和透射电子显微镜对其进行表征;根据金汞齐的形成原理,通过金纳米棒的长短径比值下降所造成的溶液颜色的明显变化,快速检测体系中不同浓度的维生素C。结果当检测体系中出现维生素C时,颜色由蓝色变为橙色;在维生素C浓度为1~100μmol/L和250—2000μmol/L范围内时,其浓度与体系吸光度比值(A_(530)/A_(640))呈现明显的线性关系,相关系数分别为0.9894和0.9843,检出限为0.067μmol/L。结论该体系下制备的金纳米比色探针可以实时快速检测维生素C的含量。     

金纳米粒子在液／液界面自组装

以甲苯作溶剂,硼氢化钠作还原剂,在液/液两相界面处,通过还原氯金酸的方法制备了金纳米粒子.分别研究了4-辛基溴化铵作为相转移剂和稳定剂制备的金溶胶体系,并用紫外可见分光光度计、红外光谱、原子力显微镜分别对金纳米体系及其自组装行为进行了表征.结果表明:配体修饰后,金溶胶在有机相的原溶液中是相当稳定的,但继续补加甲苯或其他物质后,金溶胶体系变得不太稳定,并很快趋于沉降状态.     

氧化锌纳米颗粒-海藻酸钠/壳聚糖双层复合膜的制备及特性

本研究基于层层组装流延法制备了载有氧化锌纳米颗粒的海藻酸钠/壳聚糖双层复合膜。通过评价机械、阻水及光学性质研究了氧化锌纳米颗粒对双层复合膜特性的影响,进而借助原子力显微镜、扫描电子显微镜、傅里叶变换红外光谱和热重分析对双层复合膜结构进行表征。结果表明,海藻酸钠/壳聚糖双层膜在添加氧化锌纳米颗粒后,抗拉强度提高,断裂伸长率、水溶性、水蒸气透过性和透光性降低,而外观色泽没有明显变化。从双层膜的微观结构看,随着氧化锌纳米颗粒添加浓度由0.25%（w/w）增加至1.00%（w/w）,海藻酸钠/壳聚糖双层复合膜表面出现颗粒团聚,粗糙度Ra从3.12 nm增加至3.53 nm。红外和热重分析表明,氧化锌纳米颗粒与海藻酸钠和壳聚糖之间存在较强的氢键相互作用,使得双层复合膜的热稳定性增强。综上,氧化锌纳米颗粒-海藻酸钠/壳聚糖双层复合膜具有优良的包装特性和适用性。     

金、银纳米颗粒溶胶对三种瘦肉精分子拉曼表面信号增强效果及性质比较研究

采用柠檬酸钠还原法制备了银溶胶以及三种不同粒径大小的金溶胶作为拉曼表面增强剂,通过紫外-可见吸收光谱及透射电镜(TEM)比较其尺寸、粒度、分散性及稳定性,后选取盐酸氯丙那林、硫酸特布他林和盐酸班布特罗三种β受体激动剂类药物作为检测对象,观察拉曼信号增强效果。结果表明,金、银溶胶对β受体分子的表面增强拉曼信号增强信号基本上没有干扰。金溶胶的纳米粒子大小对于吸附能力有一定程度的影响,其颗粒大小更易于通过加入柠檬酸钠的方式进行调节,而银纳米溶胶颗粒粒径较不易控制。金溶胶能较长时间保持稳定,而银溶胶较易发生沉淀,但银纳米颗粒与目标分子结合后能产生更为强烈的共振现象,与金溶胶相比具有更强的表面增强活性,在拉曼信号增强目标分子时效果更好。     

李斯特菌免疫检测用胶体金的制备及抗体标记

单增李斯特菌是重要的食源性致病菌,可危害人体健康,造成经济损失。加强食品中单增李斯特菌的检测,是降低食品安全风险的有效手段。胶体金免疫层析技术以胶体金作为示踪物,结合抗原抗体反应应用于食品安全快速检测领域。通过柠檬酸三钠还原氯金酸的方法制备胶体金溶液。胶体金最佳制备条件为:25 m L 0.01%氯金酸水溶液中加入1 m L 1%柠檬酸三钠水溶液,反应时间5 min。利用李斯特菌菌体蛋白抗体标记胶体金来制备探针,最佳标记p H值为8.4,最佳标记蛋白抗体量为12μg/m L。制备的胶体金探针具有生物活性,可用于食品中单增李斯特菌快速检测方法的开发。     

Effect of stabilizer on drying characteristics and quality of mango soy fortified yoghurt

Mango soy fortified yoghurt (MSFY) samples were prepared in the laboratory using the optimized blend formulation. Stabilizers were added during preparation of MSFY, which was then dried in a recirculatory convective dryer in 4-mm-thick forms using hot air at 50 °C and an air velocity of 2.5 m/s with 80% air recirculation. The starter counts, acetaldehyde retention, colour change and dispersibility of the dried control (MSFY) as well as MSFY containing stabilizers were determined. The effects of the amount (0.2, 0.4 and 0.6 g/100 g MSFY blend) and type (gelatin, pectin and sodium alginate) of stabilizers on drying characteristics of MSFY were studied. An increase in the level of the stabilizer in MSFY increased the drying rate. The effective moisture diffusivity increased with the increase in the amount of stabilizer added. The addition of gelatin and pectin to MSFY improved starter culture counts after drying, while the addition of sodium alginate had a negative effect. The addition of stabilizers improved acetaldehyde retention in the samples in all cases. An increase in stabilizer addition rate, increased the change in colour. Most of the MSFY samples with stabilizer had better dispersibility than those without stabilizer.     

速冻紫薯丁制备工艺研究

以新鲜紫薯为原料,将紫薯切丁后经护色、速冻后冻藏制备速冻紫薯丁。以护色工艺作为研究重点,分别采用热烫护色,海藻酸钠和壳聚糖涂膜护色,并以不护色直接真空包装作为空白对照组进行实验。以冻藏过程中PPO活性、褐变强度、色泽、糖类物质(淀粉,还原糖,总糖)的变化作为衡量指标,优选制备工艺。结果表明:1.6%的海藻酸钠涂膜护色后再经速冻后冻藏是最佳的速冻紫薯丁制备工艺,保质期可达90d。     

DIY印染用多色胶囊的制备及性能研究

借鉴微胶囊制作原理及制备工艺,以海藻酸钠与壳聚糖为壁材,染料或涂料为芯材,制作多色胶囊应用于DIY染色。讨论了海藻酸钠用量、壳聚糖用量、黏合剂用量、染料与氯化钠复配比、温度等对产品性能的影响。通过单因素实验得出优化制备工艺为:海藻酸钠1.0%,壳聚糖0.5%,染料与氯化钠质量比1.0∶2.7,不添加黏合剂,温度30℃。采用一步法制备的多色胶囊成型性好、出色率高,DIY产品各项色牢度均优良。     

白果饮料的稳定性分析

本试验研究了不同稳定剂对白果饮料稳定性的影响。以白果为主要原料,加入柠檬酸、白砂糖、羧甲基纤维素钠、卡拉胶和海藻酸钠等辅料,经过预处理、打浆、过滤、磨浆、调配、均质、脱气、灭菌和罐装等工艺制成白果植物饮料。通过单因素试验和正交实验研究3种复配稳定剂的最佳配比,以果汁沉降率和感官评分为评价指标,得到了白果饮料复配稳定剂的最佳配比为羧甲基纤维素钠0.05%、卡拉胶0.08%和海藻酸钠0.06%,沉降率为2.45%。同时,白果饮料色泽鲜亮,质地均匀,无沉淀和分层,具有白果特有香气,口感细腻润滑,黏稠适中,酸甜可口,是一款老少皆宜的植物饮料,进而为白果的食品加工相关研究提供参考。     

Effect of emulsifying salts on the physicochemical properties of processed cheese made from Mozzarella

The aim of this study was to investigate the effect of different types and concentrations of emulsifying salts (trisodium citrate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and disodium orthophosphate) on the physicochemical properties of processed cheese. The physicochemical composition, texture profile, degree of casein dissociation, fat particle size, color, and nuclear magnetic resonance profile (NMR) of processed cheese were determined. Hardness, degree of casein dissociation, and pH increased as the concentration of emulsifying salts increased. The fat particle size of processed cheese was significantly influenced by the type of emulsifying salts, with processed cheese made with sodium hexametaphosphate having larger particles (4.68 μm) than cheeses made with the other salts (from 2.71 to 3.30 μm). The processed cheese prepared with trisodium citrate was whiter than those prepared with the other emulsifying salts. The NMR analysis showed that the relaxation time of processed cheese of 10 to 100 ms accounted for a major proportion, indicating that the moisture in processed cheese was mainly bound water combined with the fat globule and hydrated casein.     

Microencapsulation of β-galactosidase with different biopolymers by a spray-drying process

The aim of this work was to investigate the possibility of producing microparticles containing β-galactosidase, using different biopolymers (arabic gum, chitosan, modified chitosan, calcium alginate and sodium alginate) as encapsulating agents by a spray-drying process. This study focused on the enzyme β-galactosidase, due to its importance in health and in food processing. Encapsulation of β-galactosidase can increase the applicability of this enzyme in different processes and applications. A series of β-galactosidase microparticles were prepared, and their physicochemical structures were analyzed by laser granulometry analysis, zeta potential analysis, and by scanning electron microscopy (SEM). Microparticles with a mean diameter around 3 μm have been observed, for all the biopolymers tested. The microparticles formed with chitosan or arabic gum presented a very rough surface; on the other hand, the particles formed with calcium or sodium alginate or modified chitosan presented a very smooth surface. The activity of the enzyme was studied by spectrophotometric methods using the substrate ONPG (O-nitrophenyl-β,d-galactopyranoside). The microencapsulated β-galactosidase activity decreases with all the biopolymers. The relative enzyme activity is 37, 20, 20 and 13%, for arabic gum, modified chitosan, calcium alginate and sodium alginate, respectively, when compared with the free enzyme activity. The enzyme microparticles formed with arabic gum shows the smallest decrease of Vmax, followed by the calcium alginate, sodium alginate, and modified chitosan.     

不同影响因素对三元食品胶溶液粘度的影响

利用德国HAAKE公司生产RS75应力控制流变仪,考察了改变pH、添加蔗糖、氯化钠和柠檬酸钠、进行冻融处理、添加大豆多肽等因素,对三元混合胶(卡拉胶∶魔芋胶∶刺槐豆胶为2∶2∶1)溶液粘度的影响。结果表明,在强酸、强碱条件下,溶液粘度均有所下降,但是碱性条件下胶体溶液的粘度相对稳定;在一定范围内蔗糖、氯化钠和柠檬酸钠均能降低胶体溶液的粘度,而两种钠盐降低胶液粘度的幅度较大;无论是冷冻处理还是冷藏处理都可降低胶体溶液的粘度;大豆多肽的加入也会在一定程度上降低混合胶溶液的粘度,改变加料方式可以减小这种影响。     

陶瓷覆聚乙烯醇——海藻酸钠膜固定化糖化酶的研究

用陶瓷颗粒吸附糖化酶后,再以不同配比的聚乙烯醇-海藻酸钠复合溶胶覆膜,分别对固定化条件、米氏常数、酶活残留率进行了研究,结果表明:陶瓷颗粒聚乙烯醇复合溶胶固定化糖化酶的条件是:聚乙烯醇:海藻酸钠配比为6∶4,溶胶浓度为7%,固化时间为120min。米氏常数为60.17mg/mL,酶活残留率为78%;陶瓷颗粒覆海藻酸钠复合溶胶固定化糖化酶的条件是:海藻酸钠∶聚乙烯醇配比是8∶2,溶胶浓度为1.5%,固化时间为90min。米氏常数为35.5mg/mL,酶活残留率为38%。     

Microencapsulation of enzymes for potential application in acceleration of cheese ripening

An encapsulation efficiency of 70% was achieved when flavourzyme was encapsulated in selected polymers and gelled in 0.1 m CaCl₂ containing 0.1% (w/v) chitosan. Enzyme retention in capsules did not increase with alginate concentration or with coating of capsules with 0.15% (w/v) alginate or 0.05% (w/v) poly l-lysine. Gelling duration of 10 min was found to be optimum, while 2.0% trisodium citrate was necessary for efficient release of encapsulated flavourzyme. During 10-week storage after freeze-drying and freezing, about 80% retention of enzyme activity was noted in flavourzyme capsules with or without poly l-lysine coating, while air-dried capsules retained about 53% activity and 32% on coating with poly l-lysine over 10 weeks. Flavourzyme leakage from capsules increased with an increase in the duration of the simulated cheese press from 4 to 16 h. Capsule addition before rennetting resulted in an even distribution compared with capsule addition before salting.     

两种海藻酸钠基凝胶的溶胀和质构性能

壳聚糖、果胶和海藻酸钠是天然多糖,具有良好的生物相容性和生物可降解性等优点。以CaCl_2为交联剂制备壳聚糖-海藻酸钠水凝胶和果胶-海藻酸钠水凝胶,研究Ca Cl2浓度、多糖质量比(壳聚糖与海藻酸钠、果胶与海藻酸钠)和交联温度对水凝胶在模拟人体胃肠道环境(pH 1.2胃、pH 6.8小肠、pH 7.4结肠缓冲溶液)中溶胀性能的影响。当壳聚糖或果胶和海藻酸钠质量比为1.25∶1、CaCl_2浓度为0.09 mol/L、温度为60℃时,制备的水凝胶在pH 1.2溶液中溶胀率最小,在pH 6.8和pH 7.4溶液中溶胀率较大;结果表明所制备水凝胶具有pH值敏感性。此外,在优化条件下水凝胶具有较好的质构性能。