Stability and release properties of curcumin encapsulated in Saccharomyces cerevisiae, β-cyclodextrin and modified starch

Curcumin, a polyphenol with pharmacological function and colouring power, was encapsulated in baker’s yeast (Saccharomyces cerevisiae) cells, β-cyclodextrin (β-CD) and modified starch (MS) by various methods. The encapsulation forms were evaluated for their efficiency in overcoming curcumin’s heat, light and oxygen sensitivity (storage stability). The release (dissolution) profile of curcumin in simulated gastric (SGF) and pancreatic fluid (SPF) was, also, obtained. All the encapsulation forms drastically increased curcumin’s solubility in SGF. A rapid dissolution of curcumin was observed for β-CD and MS microcapsules in SGF while, in yeast microcapsules, a slow and prolonged release occurred, along with low degradation rate in SPF. All the microcapsules tested protected curcumin against oxidation in environments of elevated relative humidity (%RH) and yeast microcapsules stabilized curcumin at RH above 75.5%, where oxidation was significantly increased. Yeast cells offered better protection to curcumin than did β-CD or MS against deleterious photochemical reactions and against heat degradation following isothermal (inert or oxidative) heating at 200 °C. Heating at lower temperatures (isothermal and non-isothermal) revealed that β-CD and MS can also enhance curcumin’s heat resistance.     

An investigation into the supramolecular structure,solubility, stability and antioxidant activity of rutin/cyclodextrin inclusion complex

The formation of supramolecular inclusion complexes between rutin and four cyclodextrins, namely β-cyclodextrin (β-CD), (2-hydroxypropyl)-α-cyclodextrin (HP-α-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) and (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD), and the effects of the complexation on the stability and antioxidant activity of rutin were investigated. Results from phase-solubility studies showed that rutin formed 1:1 stoichiometric inclusion complexes with HP-α-CD, β-CD, HP-β-CD and HP-γ-CD; the complexes formed with HP-γ-CD and HP-β-CD had the greatest stability constants, followed by β-CD and HP-α-CD. Thermodynamic studies demonstrate that the inclusion of rutin into HP-β-CD was an exothermic process which occurred spontaneously. Two-dimensional rotating-frame nuclear Overhauser effect spectroscopy (2D ROESY) ¹H NMR analyses show that the A ring of rutin was the part of the molecule that most likely inserted into the cavity of HP-β-CD, thus forming a supramolecular inclusion complex. Formation of such an inclusion complex conferred moderate degrees of protection to rutin from degradation by heat and UV radiation during storage, and significantly enhanced its antioxidant capacity as determined by three different procedures.     

Relationship between chlorophyll a and β-carotene in a lipid-containing model system during illumination

The relationship between chlorophyll a (Chl a) and β-carotene during illumination in the presence of fatty acid esters, methyl stearate methyl oleate and methyl linoleate was studied. Mixtures of Chl a, β-carotene and fatty acid esters were exposed to a 40 w light for 3 h. Isomerization and degradation reations of Chl a and β-carotene were monitored using HPLC with diode array detection Three isomers of Chl a and four cis isomers of β-carotene were separated and detected. Both the degradations of total amount of Chl a and β-carotene fit the first-order model. The degradation rate of total amount of β-carotene was highest in methyl stearate, followed by in methyl oleate and in methyl linoleate, while a reverse order was observed for the degradation rate of total amount of Chl a. In the presence of three fatty acid esters, Chl a is more susceptible to isomerization and degradation than β-carotene, and the degradation rates for both Chl a and β-carotene are significantly different (p < 0.05).     

Preparation,characterisation and activity of the inclusion complex of paeonol with β-cyclodextrin

The inclusion complex of β-cyclodextrin (β-CD) and paeonol (2′-hydroxy-4′-methoxyacetophenone, PAE) was synthesised and characterised by thermal gravimetric analysis (TGA) and two-dimensional rotating frame spectroscopy (2D ROESY). The antioxidant activity and tyrosinase inhibition activity were also studied. The TGA results indicated that the thermal stability of PAE was improved when it was included with β-CD. Based on the 2D ROESY analysis, an inclusion structure of the PAE–β-CD complex was proposed, in which PAE penetrated β-CD in a tilted manner due to the interaction of intermolecular hydrogen bonds between PAE and β-CD. The complex of PAE with β-CD increased the antioxidant activity and tyrosinase-inhibiting activity of PAE.     

微波-β-环糊精协同提取茶叶中茶多酚及抗氧化性的研究

以β-环糊精及其衍生物为提取介质,用微波辅助提取茶叶中的茶多酚,并用DPPH法和水杨酸法检测了茶多酚提取液的抗氧化性。实验结果表明:以60%乙醇为溶剂,β-环糊精与茶叶质量比为1:0.8,微波作用时间1min,作用功率260W,液料比40:1为最佳提取条件。在β-环糊精介质中茶多酚的提取率和对自由基的清除率均提高,提取液对DPPH.的清除作用小于对羟基自由基(.OH)的清除作用。     

Kinetic Characterization of Chimeric Cyclomaltodextrin Glucanotransferase from Genes of Two Alkalophilic Bacillus

The chimeric CGTase, which was constructed genetically with two β-CD forming type enzyme genes of different species of alkalophilic Bacillus, was characterized by comparing with the actions of parent enzymes. The final composition of CDs in the reaction digest from starch by the chimeric enzyme, especially in the yield of α-CD, was different from those by parent enzymes, and total yields of CDs by these enzymes were almost the same. The chimeric enzyme catalyzed the formation of β-CD as a major action from starch, the rapid synthesis of α-CD from other CDs and maltooligosaccharides and the slow degradation and interconversion of α-CD to others. From these results, the role of second and third segments in the enzyme molecules was discussed.     

蛋清蛋白-β-环状糊精复合物对小龙虾虾仁冻融稳定性的影响

以蛋清蛋白（EWP）和β-环状糊精（β-CD）为原料制备新型抗冻剂,通过单因素实验和响应面试验,得到最佳抗冻活性的EWP-β-CD复合物的制备条件,然后将不同浓度（2%、4%和6%）的EWP-β-CD复合物应用于小龙虾虾仁的四次冻融循环体系,研究EWP-β-CD复合物对虾仁的抗冻保护作用。结果表明,制备EWP-β-CD复合物的最佳条件为pH7.0,β-CD与EWP的复合比1:10,热处理温度75℃,在最优条件下EWP-β-CD复合物的抗冻活性为84.09%±1.06%。将此条件下的EWP-β-CD复合物应用于小龙虾虾仁的冻融循环,虾仁添加EWP-β-CD复合物经过4次冻融循环后,保水性得到改善,硬度和咀嚼性明显提高,并且不会影响虾仁色度。当EWP-β-CD复合物的添加量为4%和6%时,抑制虾仁蛋白质的降解和脂肪氧化的效果明显优于商业抗冻剂。响应面法对EWP-β-CD复合物的制备条件优化合理,并初步证实其对虾仁品质有一定的保护作用,为后续研发低甜度、低热量的抗冻剂提供一定的理论基础。     

Preparation,physicochemical characterization and release behavior of the inclusion complex of trans-anethole and β-cyclodextrin

Trans-anethole (AT) has a variety of antimicrobial properties and is widely used as food functional ingredient. However, the applications of AT are limited due to its low water solubility, strong odor and low physicochemical stability. Therefore, the aim of this work was to encapsulate AT with β-cyclodextrin (β-CD) for obtaining inclusion complex by co-precipitation method. The measurements effectively confirmed the formation of inclusion complex between AT and β-CD. The results showed that the inclusion complex presented new solid crystalline phases and was more thermally stable than the physical mixture and β-CD. The phase solubility study showed that the aqueous solubility of AT was increased by being included in β-CD. The calculated stability constant of inclusion complex was 1195 M^− 1, indicating the strong interaction between AT and β-CD. Furthermore, the release study suggested that β-CD provided the protection for AT against evaporation. The release behavior of AT from the inclusion complex was controlled.     

沙枣花精油微胶囊制备工艺优化及缓释性能

本文以沙枣花精油为芯材,β-环糊精(β-CD)为壁材包埋制备沙枣花精油微胶囊,综合考察壁芯比、乙醇与精油体积比、β-CD与加水量比、包埋温度、包埋时间5个因素对微胶囊包埋得率的影响,并通过响应面法优化工艺条件。结果表明,确定沙枣花精油最佳包埋条件为:壁芯比5:1 (g/mL)、乙醇与精油比30:1(mL/mL)、加水量与β-CD比8:1 (mL/g)、包埋时间2 h、包埋温度46 ℃,此工艺条件下的微胶囊包埋得率为75.15%±0.24%,与预测值接近。红外光谱和扫描电子显微镜结果显示沙枣花精油在β-CD中的存在。缓释性能研究表明,沙枣花精油微胶囊的精油挥发率(7.22%)与过氧化值(19.7%)都有明显下降,因此可延长沙枣花精油的使用寿命,提高精油的利用率,从而为沙枣花精油在食品领域中广泛使用提供一定的方法支持。     

Cholesteryl Linoleate Oxidation in Freeze-Dried Model and Beef Systems

An attempt was made to determine lipid oxidation by measuring the oxidative loss of cholesteryl linoleate in a freeze-dried model system and in a meat system. In the model system containing cholesteryl linoleate (lg), cobalt chloride (10 ppm) and cellulose (24g), there was a direct relationship between the loss of Cholesteryl linoleate and pentane production, an index of lipid oxidation during storage. As the pentane production increased rapidly, the cholesteryl linoleate concentration decreased accordingly. However, in the meat system, the loss of cholesteryl linoleate extracted by isopropanol was not evident throughout the storage period while a significant amount of pentane was produced. Therefore, this method was suitable for following the oxidative rancidity for the model system but not for the meat system under the experimental conditions of the present study.     

麦芽糊精摩尔质量分布对β-环糊精合成的影响

环糊精是一类广泛应用于食品、医药、化工、农业等领域的环状低聚糖。文中研究了以麦芽糊精为底物,其摩尔质量分布对β-环糊精(-βCD)合成的影响。通过GPC分析,运用Sephacryl 200-HR和Sephacryl 400-HR2种凝胶分析麦芽糊精的摩尔质量分布,通过高效液相色谱法(HPLC)分析其小分子糖组成。结果表明:不同葡萄糖值(DE值)的麦芽糊精具有明显不同的分子组成,随着DE值升高,麦芽糊精分子的分支化程度逐步升高,分子链长减小,小分子糖含量呈上升趋势;生产工艺不同可引起DE值相近的麦芽糊精出现摩尔质量分布的较大差异;麦芽糊精分子组成可影响β-CD的合成,应用适当链长的底物在一定程度上可促进环化反应,链长过长易引起歧化反应,而链长过短则会导致β-CD因耦合反应而降解;β-CD的转化率随麦芽糊精分子分支化程度的升高而降低,重均摩尔质量约在(MW)43 053~18 793 g/mol左右且分支较少的线性麦芽糊精分子可认为是环化反应的最适底物。     

Effects of conjugated linoleic acid on the degradation and oxidation stability of model lipids during heating and illumination

The effects of methyl conjugated linoleate (MCLA) on the degradation and oxidative stability of model lipids, methyl linoleate (ML), methyl oleate (MO) and methyl stearate (MS), during heating at 100, 150 or 200°C for 3 h or illumination at 4000 lux for 14 days were studied. Results showed that under either temperature treatment or illumination, MCLA was the most susceptible to degradation, followed by ML, MO and MS. At 100°C, peroxide formation was the main reaction in each model lipid. However, at 150°C, peroxide formation was the main reaction in the initial period of heating, followed by degradation. At 200°C, the degradation was the major reaction. In contrast, peroxide formation was the main reaction for each model lipid during illumination. The addition of MCLA may slow degradation of each model lipid during heating. However, the oxidation stability of the whole system (model lipid plus MCLA) may also be decreased. Under light storage, the effect of MCLA was insignificant.     

微波-β-CD协同提取山楂中熊果酸

以β-CD的乙醇溶液为介质,用微波辅助提取山楂中的熊果酸,并用紫外分光光度法测定山楂中熊果酸的得率。在单因素实验的基础上,采用正交试验。研究表明适宜的提取工艺条件为:乙醇体积分数为80%,微波功率50%,微波提取时间90 s,料液比(g∶mL)1∶25,β-CD的用量m(山楂)∶m(β-CD)为1∶1。正交试验优化结果为:乙醇体积分数80%,微波时间为100 s,微波功率为60%,m(β-CD):m(山楂)为1∶1。在优化提取条件下,山楂中的熊果酸得率为:3.374mg/g。β-CD的加入有效的提高了熊果酸的得率。     

改性β-环糊精对茴香醛、柠檬醛的包结研究

采用羟丙基化改性的β-环糊精(β-CD)对茴香醛和柠檬醛进行了包结研究,考察了包合反应的影响因素。结果表明,在水用量为15mL/g改性β-CD的水溶液中,改性β-CD与茴香醛或柠檬醛的摩尔比为1:1、包合反应时间为90min时,茴香醛和柠檬醛的包合率均大于98%。所得产品经紫外光谱、薄层色谱和红外光谱法鉴定为改性β-CD与茴香醛或柠檬醛的包合物。与β-CD比较,改性β-CD对柠檬醛、茴香醛的包合能力明显增强。     

Complexes between linoleate and native or aggregated β-lactoglobulin: Interaction parameters and in vitro cytotoxic effect

The dairy protein β-lactoglobulin (βlg) is known to form a complex with fatty acids (FA). Due to industrial processing, βlg is often in its non-native form in food products, which can modify the FA/βlg complex properties. We investigated the interaction of bovine βlg, in selected structural forms (native βlg, a covalent dimer and as nanoparticles), with linoleate (C18:2). Using fluorescence and Isothermal Titration Calorimetry, linoleate was found to bind βlg at two different binding sites. Regardless of the structural state of βlg, association constants remained in the same order of magnitude. However, the stoichiometry increased up to 6-fold for nanoparticles, compared to that of native βlg. The impact of these structural changes on linoleate uptake in vitro was measured by cytotoxicity assays on Caco-2 cells. The order of cytotoxicity of linoleate was as follows: free > complexed to dimers > complexed to nanoparticles > complexed to native βlg. Therefore, the in vitro cytotoxicity of linoleate could be modulated by altering the state of βlg aggregation, which in turn affects its binding capacity to the FA.     

β-环糊精/二烃基五硫化物包合物的制备及其摩擦磨损性能实验研究

采用共沉淀法制备了β-环糊精（β-CD）/二烃基五硫化物（RC2540）包合物,使用红外光谱（FrIR）和热重分析（TG）对其进行表征.用四球摩擦副考察了包合物作为聚乙二醇600基础液添加剂时的摩擦磨损性能.结果表明β-CD/RC2540包合物减摩抗磨性能优于β-CD,其抗磨性能随包合物添加量增加而增强,高载荷（≥392 N）时,磨斑直径比添加β-CD的小25％～30％.摩擦作用导致β-CD/RC2540包合物外壳β-CD分子发生分解,释放腔内的RC2540,RC2540分解产生的活性S元素在摩擦表面形成摩擦化学反应膜起到较好的润滑效果.     

负载纳米TiO2和β-环糊精的多功能织物的研究

以钛酸丁酯为原料,合成了纳米二氧化钛溶胶.在溶胶中加入β-环糊精(β-CD),采用轧烘焙的方法将此溶胶整理到棉织物上.对织物的抗紫外性、光催化性、抗茵性、吸香增重率等的测试结果表明,加入β-CD后能提高织物的吸香性能和抗茵性以及对甲醛的光催化降解性,而对织物的强力和白度影响不大,整理织物具有优良的抗紫外性.     

Structure of Inclusion Complexes of Cyclodextrins with Triglyceride at Vegetable Oil/Water Interface

The interfacial tension of vegetable oil (soybean oil or coconut oil)/ water interface decreased with the increase of cyclodextrin (CD) concentration. The interfacial excess and interfacial area were calculated from the Gibbs’ adsorption equation. The average number of CD molecules including a fatty acid residue of soybean oil at the interface was estimated at 2.4 for each of α-CD and β-CD. The average number of CD molecules complexed with a fatty acid residue of coconut oil was 1.8 for α-CD and 1.7 for β-CD. These results suggested that the CD molecules formed the inclusion complex with the triglyceride according to the chain length of fatty acid residue at the interface.     

3种生物柴油氧化降解特性研究

利用Rancimat试验法氧化降解菜籽油生物柴油、大豆油生物柴油、小桐子油生物柴油,采用GC-MS测定不同氧化时间下的生物柴油中主要脂肪酸甲酯含量变化,进而通过半衰期法计算动力学参数(反应级数、速率常数),同时研究生物柴油氧化深度与热值的关系,并对氧化前后生物柴油样品进行FTIR分析。研究表明:除大豆油生物柴油中的硬脂酸甲酯外,3种生物柴油中主要脂肪酸甲酯氧化降解反应级数都为1;氧化降解反应速率从小到大依次为棕榈酸甲酯、硬脂酸甲酯、油酸甲酯、亚油酸甲酯、亚麻酸甲酯;氧化降解时间与热值为一元三次函数关系;另外,FTIR分析表明在1 740 cm~(-1)处的吸光度随着氧化降解时间延长不断增加,说明氧化程度不断加深。     

超高压促进β-环糊精向大米颗粒内部的有效渗入

文中探究了超高压对β-环糊精在大米颗粒中的渗入情况。在粳米浸泡液中添加2%β-环糊精在60℃温水中浸泡30 min,随后在超高压(100～500 MPa)下浸泡20 min,最后将浸泡后的大米蒸汽催熟并焖饭制成米饭。采用高效液相法定量检测浸泡米液残留的β-环糊精含量,研究发现随着压强的增大,浸泡液中β-环糊精的含量显著降低,表示渗入米粒的β-环糊精更多。通过β-环糊精包埋1,8-二羟基蒽醌荧光剂来示踪β-环糊精在超高压浸泡过程中向米粒内部的渗入,用激光共聚焦显微镜观察常压处理和超高压处理米饭切片的荧光分布。实验发现超高压能有效地促进β-环糊精渗透到米粒内部。