Release Behavior of Flavor Encapsulated CD in Slurry Solution Under Boiling Conditions

Cyclodextrin (CD) can control flavor release rate and protect the flavor from volatilization by the formation of inclusion complex with flavor compounds. However, the flavor release rate during cooking, particularly in boiling water has hardly been understood. In this study, flavor release rate of flavor encapsulated CD in slurry or turbid solution under boiling condition was investigated. The release rate constants of methyl caproate and d-limonene depended on the CD concentration, whereas, those of phenyl ethanol hardly did. The plot of a reciprocal number of apparent release rate constant to CD concentration for d-limonene stability constant under boiling condition was obtained. Stability constants for d-limonene in α-CD and β-CD were 185 and 38 M⁻¹, respectively. These stability constants were smaller than the order of 1000 M⁻¹ at room temperature. These results suggested that the addition of CD for protection of flavors in boiling water might have small effect in comparison to that at room temperature. The behavior of flavor release in the boiling water correlated well with the first-order release rate equation, which can be described by the film theory of the interfacial mass transfer.     

Trace elements in HPLC silica gel

Trace elements in different silica gels are determined by neutron activation analysis. The presence of 20 elements in the ppm range and of 15 elements in the ppb range is established in all silica gels; even in spherical material probably obtained via an organosilicium starting material. Removal of these elements by acid treatment before and after derivatization to a reversed-phase is studied. This is only partially effective. The resulting HPLC phases are, however, much better in cases where trace elements are detrimental. Even octadecyl derivatized silicagel can withstand boiling in 12 N hydrochloric acid without loosing significant amounts of bonded organic material.     

脂肪醛和脂肪酮的沸点与分子结构关系的拓扑化学研究

根据分子拓扑学原理,通过采用信息量丰富的染色分子图代替隐氢图,借助于距离矩阵表征分子图中顶点的连接性和标识分子图中顶点性质的差异,发展了一种适用于含杂原子分子体系结构性能研究的新方法,据此探讨了脂肪醛和脂肪酮的沸点与分子结构之间的关系,提出一个既能合理表征结构性能关系、又能预测沸点的定量关系式。结果表明,沸点预测值与实验值的一致性令人满意,平均误差0.21%。     

Simulated distillation of wax samples using supercritical fluid and high temperature gas chromatography

Simulated distillation boiling range distributions have been compared for high boiling petroleum wax samples using high temperature gas chromatography and supercritical fluid chromatography. Midpoint (50 % off) temperature differences were small, and average differences between the two types of analyses were less than 6° Details of optimization of the HTGC and SFC systems and injection techniques used are reported.     

药厂废液中有机酸的分离分析

利用减压蒸溜法分离废液中的低沸点有机酸,结合红外光谱、气相色谱、质谱,确定了废液中以乙酸、丙酸为主的10种有机酸的结构,其含量占分析废液的2.64%。其中丙酸含量最高,其次为乙酸。同时被检测到的还有乙醇,乙醛等。另外通过柱层析分离高级脂肪酸,并进行衍生化处理,经GC、GC-MS检测,确定了四种高沸点有机酸的结构,含量为1.71%。9,12-十八二烯酸含量相对较高。因此有机酸占废液总量的质量分数为4.35%。     

Optimization and application of the large volume on-column introduction (LOCI) technique for capillary GC with preliminary on-line capillary solvent distillation/concentration

This report describes an on-line capillary GC injection system which enables on-column injection of a hundred or more microliters, and yields separations comparable with those obtained from on-column injection of 1–2 microliters of solutions a hundred times more concentrated. Precision, carry-over, linearity, and discrimination are comparable with those of classical sample-introduction techniques. A selection of polar and high boiling compounds has been examined, and excellent peak shapes obtained for hundreds of injections. Initial results indicate that maintenance and long-term reproducibility will also be comparable with those of classical techniques. The instrument utilizes a version of the large volume on-column injector with solvent diversion described in an earlier communication, with the addition of a method for independent heating of the retention gap. This modification reduces the effects of activity in the retention gap and improves the capability of the technology to handle complex mixtures. It also increases reliability and system lifetime, fits readily into most GC ovens, is easily automated, and should be compatible with all capillary GC detectors.     

分子极化效应指数与脂肪族醛酮的沸点

建立物质的定量结构—活性相关性(QSAR)和定量结构—性质相关性(QSPR)的研究一直受到化学工作者的关注。用拓扑指数研究饱和烃的各种物理化学性质已经有大量报道1 4。本文讨论了分子极化效应指数[5]与脂肪族醛酮沸点的关系,力求寻找到一个适用范围广,并且具有分子结构特征的计算脂肪族醛酮沸点的计算公式。1　分子结构参数的确定脂肪族醛酮分子中羰基的存在,使相同碳原子数的醛酮沸点比烷烃升高很多。我们以醛酮分子中的烷基极化效应指数(PEI)的差值(ΔPEI)[6]来表示羰基位置对醛酮沸点的影响:ΔPEI=PEIB,N-PEInrm,N(1)式中,…     

应用拓扑方法计算烷烃的沸点

根据分子结构的特点 ,用距离矩阵表征分子中原子的连接性 ,用染色因子标识原子性质的差异 ,探讨了烷烃的沸点与分子结构之间的定量关系 ,据此发展了一种直接根据分子结构信息计算烷烃沸点的方法。对75 2种烷烃 (C1到C10 0 )的计算结果表明 ,沸点的预测值十分接近实验值 ,平均绝对误差 1.36K ,平均相对误差 0 .2 9% ,计算精度优于文献方法。     

有效碳链长度与脂肪醇的沸点

脂肪醇沸点(b.p.)变化规律可用下述关系式表示:ln(800.386-T~b)=6.64919-2.94828×10^-^2N~E~C~C+0.150955ΔPEI。式中N~E~C~C为醇中烷基的有效碳链长度, ΔPEI是具有相同碳原子数目的支链烷基与直链烷基的极化效应指数的差值, 它表示羟基对醇的沸点的影响。     

Specific features of explosive boiling of liquids on a film microheater

Explosive boiling of liquids on film heaters under the action of pulsed heat fluxes q = 10⁸–10⁹ W/m ² is considered. A technique of stroboscopic visualization of boiling stages with a time resolution of 100 nsec is used. Numerous scenarios of evolution of explosive boiling are demonstrated. Conditions of the thermal effect (magnitude of the heat flux, duration and repetition frequency of heat pulses) are found, which ensure single and repeated boiling, intermittent boiling, and boiling with formation of complicated multi-bubble structures. It is noted that homogeneous nucleation is a dominating mechanism of incipience of examined liquids for q > 10⁸ W/m ². __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 81–89, March–April, 2007.