枝叶精油微胶囊工艺优化及缓释性能研究

目的研究桉叶精油微胶囊的最佳包埋工艺。方法以β-环糊精为壁材制备桉叶精油微胶囊,通过单因素和正交试验研究微胶囊包埋工艺,确定最优包埋工艺条件。结果最佳包埋工艺中包埋温度为40℃,包埋时间为1.5 h,β-环糊精质量浓度为8 g/mL。在该条件下制得的微胶囊包埋率为70.33%,微胶囊收率为86.27%。缓释试验结果表明,微胶囊化可以明显降低桉叶精油的挥发速率,Avrami's方程也可以对桉叶精油微胶囊释放过程进行较好拟合。结论试验达到了预期目的,微胶囊化提高了精油利用率,延长了桉叶精油的使用寿命。     

牛至精油β环糊精微胶囊的制备及其抑菌效果研究

目的制备牛至精油β环糊精(β-CD)微胶囊,并研究其抑菌效果。方法首先,选用β-CD包埋牛至精油,通过扫描电镜观察该包埋物的外部形貌特征。其次,通过薄层色谱、红外光谱等2种方法考察是否已成功制备牛至精油β环糊精的微胶囊。然后,通过紫外分光光度计测定该包埋物的吸光度,按照一定的方法计算其包埋率。最后,选用大肠杆菌、米曲霉菌作为供试菌株,研究该包埋物的抑菌效果。结果牛至精油β环糊精微胶囊得到成功制备,其包埋率为73%,并且该包埋物具有较好的抑菌效果。结论实验达到了预期目的,即在保留牛至精油抑菌性能的同时,也使得液体的牛至精油固体粉末化。     

气相分子吸收光谱法和紫外分光光度法测定水中总氮的方法比较

用气相分子吸收光谱法和碱性过硫酸钾消解紫外分光光度法分别对水中总氮行了测定,并对两种方法的测定值进行了比较,结果显示气相分子吸收光谱法的准确度、精密度较紫外分光光度法好,且紫外分光光度法分析时消解时间长,使用气相分子吸收光谱法大大缩减了分析时间。     

茶叶中氟化物的测试方法研究

为比较氟离子选择电极法、分光光度法、离子色谱法3种方法测定茶叶中氟化物含量的异同,选取低氟、中氟、高氟3种浓度水平的4类茶样共计12份,分别用上述3种方法分析并进行其检出限、测定结果、回收率、精密度的比较。结果显示:3种方法在各自检测区间内均有较好的准确度和精密度,但氟离子选择电极法检出限较其余两种方法高,不适合分析低氟的茶叶样品;分光法操作繁琐,试剂毒性大;采用离子色谱法分析茶叶中的氟化物,可以涵盖各种浓度水平的茶样,并且操作简单,可以同时测定多种阴离子。     

紫外光分光光度法测定食品包装纸用黄柏黄酮含量的研究

研究了紫外光分光光度法测定食品包装纸用色素黄柏黄酮含量的方法,以芦丁为参照品,测量波长为359 nm,平均回收率为99.90%,精密度为1.27%,说明紫外分光光度法是一种较理想的测定方法.     

紫外光分光光度法测定食品包装纸用天然色素虎杖黄酮含量的研究

研究了紫外光分光光度法测定食品包装纸用色素虎杖黄酮含量的方法,以芦丁为参照品,测量波长为359nm,平均回收率为99.96%,精密度为1.34%,说明紫外分光光度法是一种较理想的测定方法.     

食品包装用功能性添加剂灯心草黄酮含量测定的研究

研究了紫外光分光光度法测定食品包装用功能性添加剂--灯心草黄酮苷含量的方法,以芦丁为参照品,测量波长为359 nm,平均回收率为100.01%,精密度为1.72%,说明紫外分光光度法是一种较理想的测定方法.     

用紫外分光光度法测定光亮镀镍液中的硝酸根

利用活性炭作为吸附剂，采用紫外分光光度法不经分离直接测量光亮镀镍液中的硝酸根含量，结果表明，该方法具有简便快速、精密度高、准确度好等特点。     

碘量法测定制革下脚料中三氧化二铬

本文介绍了用碘量法测定制革下脚料的铬含量。研究了方法的准确度和精密度 ,比较了原子吸收分光光度法测定的数据与本法的差别 ,并排除了制革下脚料中微量铁对测定的干扰。     

分光光度法快速测定嘉陵江水体中硝酸盐氮

采用美国HACH公司最新推出的DR/5000紫外可见分光光度计,及其专用试剂测定水中硝酸盐氮含量。该法测定精密度好、灵敏度较高、准确度好,加标回收率近100%,操作简便、快速、试剂用量少。     

精油微胶囊在食品保鲜中的应用研究进展

目的 综述精油微胶囊在食品保鲜领域的研究进展,为进一步开发精油微胶囊在食品保鲜中的应用提供科学的研究基础.方法 归纳近几年制备精油微胶囊的方法及其特点,简要介绍微流控法、反向分散凝胶法、层层自组装法及电喷雾法.总结精油微胶囊在食品保鲜中的应用方式以及在果蔬、冷鲜肉制品、加工制品、粮食作物等方面的应用研究.结果 微胶囊技术可以扩大精油在食品工业中的应用,精油微胶囊作为新型的天然保鲜剂用于食品贮藏中能抑制微生物生长,延长食品的货架期.结论 精油微胶囊在食品保鲜领域有较大发展潜力.     

Gas chromatographic simulated distillation-mass spectrometry for the determination of the boiling point distributions of crude oils

The coupling of gas chromatographic simulated distillation with mass spectrometry for the determination of the distillation profiles of crude oils is reported. The method provides the boiling point distributions of both weight and volume percent amounts. The weight percent distribution is obtained from the measured total ion current signal. The total ion current signal is converted to weight percent amount by calibration with a reference crude oil of a known distillation profile. Knowledge of the chemical composition of the crude oil across the boiling range permits the determination of the volume percent distribution. The long-term repeatability is equivalent to or better than the short-term repeatability of the currently available American Society for Testing and Materials (ASTM) gas chromatographic method for simulated distillation. Results obtained by the mass spectrometric method are in very good agreement with results obtained by conventional methods of physical distillation. The compositional information supplied by the method can be used to extensively characterize crude oils.     

Antimicrobial activity of microencapsulated lemongrass essential oil and the effect of experimental parameters on microcapsules size and morphology

Lemongrass (Cymbopogom citratus) essential oil, known due to its broad-spectrum antimicrobial activity, was microencapsulated by simple coacervation. Poly(vinyl alcohol) (PVA, 78,000 Da and 88 mol% degree of hydrolysis) crosslinked with glutaraldehyde was used as wall-forming polymer. The influence of stirring rate and oil volume fraction on the microcapsule size distribution were evaluated. Sodium dodecil sulphate (SDS) and Poly(vinyl pirrolidone) were tested in order to avoid microcapsules agglomeration during the process. Depending on the experimental conditions, microcapsules in the range of 10 μm to 250 μm were obtained. Microcapsules presenting no agglomeration were obtained when SDS at 0.03 wt.% was used. The composition and the antimicrobial properties of the encapsulated oil were determined, demonstrating that the process of microencapsulation did not deteriorate the encapsulated essential oil.     

层层自组装法制备肝素微囊及其性能研究

以海藻酸钙微核为模板,采用带正电荷的聚稀丙基铵盐酸盐(PAH)和带负电荷的肝素钠(HEP),通过层层自组装(Layer-by-layer,LbL)技术构建具有多层膜结构和抗凝血活性的药物微囊.采用荧光倒置显微镜、SEM、动态光散射仪、Zeta电位仪和抗凝血仪等进行表征.结果表明,制备的海藻酸钙微核粒径约为1.5μm,尺寸均匀、分散性佳;以ALG为模板制得的LbL微囊具备典型的核壳式结构;Zeta电位检测表明,随包膜层数的增加,微囊的电位呈正负交替的变化趋势;通过体外凝血时间(PT、APtt、TT)检测微囊抗凝血活性,比较了分别以PAH和HEP作为最外层时的生物活性,其中以HEP为最外层的显著增强了材料的抗凝血性能,同时随着组装层数的增加,也提高了微囊的抗凝血性能.     

饮料酒中甲醇与杂醇油的气相色谱法分析

为了提高酒中甲醇、杂醇油测定的精密度和准确度,节省分析时间和分析成本。本实验探索研究采用丙酸乙酯作为用气相色谱法的内标物,测定饮料酒中的甲醇和杂醇油（异丁醇、异戊醇）含量的方法。采用GDX-102不锈钢填充柱进行分离,氢火焰离子化检测器检测,利用保留时间定性,并以丙酸乙酯作内标定量,并顺带测定了其中的乙酸乙酯、正丙醇和正丁醇的含量。得到了令人满意的结果：方法的准确度高,7种组分的加标回收率在90．1％～108．8％之间;方法的重现性精密度即相对标准偏差在0．00％～5．37％之间,符合国标规定的气相色谱的测定误差不大于10％的要求。     

反应性乙烯基硅油/聚脲甲醛自修复微胶囊的制备

以聚脲甲醛为囊壁、乙烯基硅油(DY-V401-310硅油)为囊芯,采用原位聚合法成功合成了具有自修复功能的新型微胶囊-聚脲甲醛包覆乙烯基硅油微胶囊.研究了搅拌速度和表面活性剂对微胶囊物理性能的影响,并通过扫描电子显微镜(SEM)、金相显微镜(MS)、激光粒度分析仪和红外光谱(FTIR)对微胶囊的表面形貌、粒径尺寸与分布及其化学结构等性能进行了研究.结果表明,十二烷基苯磺酸钠(SDBS)和明胶均对微胶囊的形成有积极作用,SDBS所制备的微胶囊粒径更小.当SDBS的加入量为1%(质量分数)时,在搅拌速度为600r/min的作用下,可得到平均粒径为123μm、较为理想的微胶囊.     

Direct encapsulation of proteins into calcium silicate microparticles by water/oil/water interfacial reaction method and their responsive release behaviors

The direct encapsulations of proteins such as lysozyme, bovine serum albumin (BSA) and ovalbumin into calcium silicate microparticles were examined by interfacial reaction method using water/oil/water emulsion (W/O/W emulsion), which was effective for the preparations of silica and calcium carbonate microcapsules encapsulating biomacromolecules. Those proteins added to the sodium silicate solution of the W/O/W emulsion were successfully encapsulated into the microparticles, which were ascertained by diffuse reflectance ultraviolet (UV) and infrared spectra. The encapsulation efficiency of the proteins depended on the molecular weight of proteins, which were also observable in the protein encapsulations into silica and calcium carbonate microcapsules. No discharge of encapsulated proteins by simple washing with deionized water indicated the secure packing of proteins into calcium silicate matrix. Ethylenediamine-N,N,N′,N′-tetraacetic acid, tetrasodium salt (EDTA·4Na) effectively extracted calcium ions from the microparticles to serve as a trigger for the release of proteins, indicating that the elimination of calcium ion initiated the discharge of encapsulated proteins. The ion exchange between calcium and sodium ions also achieved the release of proteins into aqueous solutions. The release rate of proteins such as lysozyme and BSA increased with the concentration of sodium chloride less than 1 M. In diluted solutions, potassium chloride accelerated the protein release more than sodium chloride. These characteristic release behaviors must be applied to drug delivery systems that respond to the concentration of alkaline ions in body fluid.     

微胶囊化植物精油在果蔬保鲜包装中的应用

植物精油的天然抑菌性和抗氧化活性使其在果蔬保鲜领域有着广泛的应用前景。然而,植物精油具有强烈气味、易挥发等缺点,应用效果不佳。微胶囊技术可以掩盖精油的强烈气味,保持其化学稳定性,且具有缓释效果,可以更好地发挥植物精油在果蔬保鲜包装方面的优良性能。介绍了植物精油的抑菌活性、抗氧化活性以及植物精油微胶囊的芯材、壁材和常用的制备方法,对植物精油微胶囊保鲜剂控释包装、复合保鲜薄膜包装和可食性涂膜包装在果蔬保鲜包装方面的研究现状进行综述,以期为微胶囊化植物精油在果蔬保鲜包装方面的进一步研究与应用提供参考。     

疏水改性海藻酸钠衍生物包埋丁香油的释放性

目的通过化学方法将月桂醇与海藻酸钠接枝共聚形成两亲共聚物,对丁香油进行包埋形成微胶囊,使其具有一定的缓释性和良好的抗菌效果。方法利用两亲共聚物包埋丁香油形成包合物,采用单因素实验法,以包埋率为指标,评价月桂醇与海藻酸的接枝率对包埋率的影响,并在此基础上评价接枝率对缓释性以及不同环境下的稳定性和抗菌性能。结果在一定范围内包埋率随着接枝率的增大而升高;丁香油微胶囊的挥发率为14.11%,远低于丁香油的挥发率61.25%;释放试验中,丁香油微胶囊的缓释性明显优于未改性海藻酸纳,丁香油微胶囊能稳定缓慢地释放抗菌成分,控制大肠杆菌的生长。结论月桂醇改性海藻酸钠包埋丁香油形成的微胶囊具有一定的缓释和抗菌性能,突破了丁香油因挥发性强而存在的应用限制。     

肉桂精油微囊化及其在果蔬保鲜中的应用

目的以壳聚糖、海藻酸钠为壁材,以肉桂精油为芯材,采用复凝聚法制备壳聚糖微胶囊,并将其应用于水果保鲜中。方法通过光学显微镜、扫描电子显微镜、傅里叶转化红外光谱等,确定微胶囊的最佳工艺参数、芯壁比及添加质量分数,并以芒果为实验对象,研究添加不同微胶囊质量分数的壳聚糖溶液对芒果保鲜效果的影响。结果当壳聚糖/海藻酸钠质量比为1∶2,氯化钙质量分数为1%,p H值为5,戊二醛质量分数为60%,交联时间为60 min,芯壁比为4∶1时,制备形成的壳聚糖微胶囊成球效果较好;微胶囊在壳聚糖溶液中的添加质量分数为4%时,以其涂膜的芒果保鲜效果最佳。结论肉桂精油经囊化后有效减少了气味、延缓了挥发,在果蔬保鲜中有较重要的现实研究意义。