Identification of cocoa butter equivalents added to cocoa butter I. An approach by fatty acid composition of the triacylglycerol sub-fractions separated by Ag+-HPLC

 Separation of the six sub-fractions of triacylglycerols (TAG) from cocoa butter, three cocoa butter equivalents (CBEs: calvetta, choclin and coberine) and their mixtures was carried out by silver ion high-performance liquid chromatography. The percentage fatty acid composition of all these sub-fractions was then measured by high-resolution gas chromatographic analysis of the methyl esters of the constitutive fatty acids. In particular, the percentage quantities of all acids in the fully saturated sub-fraction of pure fats and some of their mixtures were evaluated as a function of the percentage CBEs added to cocoa butter in order to devise multiple regression models. The aim was to obtain statistical tools for the identification and/or quantification of added CBEs. The results obtained show the effectiveness of TAG sub-fraction percentage fatty acid composition data for the purposes of research, as well as the potential use of stereospecific analysis of the same sub-fractions. In fact, the stereospecific analysis of TAG fractions from cocoa butter and CBEs already carried out has enabled observation of the different distributions of various fatty acids in the glycerol backbone of TAG from cocoa butter and the CBEs under study, and this will certainly result in the development of more powerful and discriminating statistical models. Received: 12 August 1997 / Revised version: 19 December 1997     

碱性红6GDN的荧光检测—高效液相色谱研究

建立了适用于分离检测碱性红６ＧＤＮ及色基的高效液相色谱荧光检测的方法。采用Ｃ１８色谱柱，甲醇－水为流动相，溴代十六烷基三甲胺为离子对试剂。碱性红６ＧＤＮ和色基荧光检测的激发波长和发射波长分别是３１０ｎｍ和５５４ｎｍ。碱性红６ＧＤＮ和色基的检出限分别是４３．５ｐｇ和５２．５ｐｇ。本方法操作简便、灵敏度高、结果可靠，是值得开拓的分析方法     

高效液相色谱分析法测定几种煲汤药材金属元素含量

采用四-(对氨基苯基)-卟啉(T4-APP)柱前衍生,以固相萃取富集,利用高效液相色谱法测定四种广东常用煲汤药材(五指毛桃、鸡骨草、海底椰和土茯苓)及其汤底中六种重金属元素:镍、铜、锡、铅、镉、汞的含量。结果表明四种药材均含有一定量的重金属元素,其中以铜含量最高,浓度范围为12.96～37.28μg/g,而汞含量最低为0.07～0.73μg/g;经过长时间煲煮后,汤底中的重金属元素残留比例有所差异,其中镉(Cd)的残留量最高,达到63.97%～76.32%,而铜(Cu)的残留量最低,仅为26.56%～36.67%。土茯苓具有最高含量的铜元素为37.28%,但其锡、铅和汞元素的含量最低,分别为0.69、0.37和0.07μg/g,并且在汤底中的残留比例最高,分别为75.36%、91.89%和85.71%;其它三种药材及其汤底中残留重金属含量相近,没有明显差异。     

高效液相色谱法测定浓缩苹果汁中棒曲霉毒素

利用全自动凝胶渗透色谱净化系统净化、在线浓缩样品,采用高效液相色谱分离,紫外检测器检测建立了浓缩苹果汁中棒曲霉毒素的检测方法。样品经乙酸乙酯:环己烷(1:1)提取,凝胶渗透色谱(GPC)净化,在线浓缩并定容,采用C18柱分离,以乙腈:水(体积比为10:90)为流动相,流速1.0ml/min;检测波长276nm。浓度0.01～10.0mg/L时线性关系良好,加标回收率为83%～107%,相对标准偏差为7.8%～11.4%,检出限0.005mg/kg。该方法操作简单、灵敏度高、重复性好。     

HPLC-ELSD法测定苦杏仁中苦杏仁苷的含量

建立了苦杏仁中苦杏仁苷的高效液相色谱-蒸发光散射检测器检测方法。采用ZORBAX Eclipse XDB-C18色谱柱(4.6mm×150mm,5μm),流动相为V(甲醇)∶V(水)=40∶60,流速1.0mL/min,柱温40℃;蒸发光散射检测器漂移管温度60℃,载气(空气)压力0.2MPa。在上述条件下测得苦杏仁苷在0.28～5.5μg范围内的线性关系良好(r=0.9975),检出底限达58ng/L,平均加标回收率为96.2%。该方法简便快捷,重现性和准确度良好,可用于实际工作中样品的测定。     

耐盐酵母添加对高盐稀态酱醪风味成分的影响

采用蒸馏萃取法提取高盐稀态发酵法发酵结束后的酱醪中的挥发性成分,采用气相色谱进行分析。结果表明,不同时期分别添加3种耐盐酵母的高盐稀态酱醪所产生的风味成分均要多于未添加酵母的酱醪,尤其在第15天添加T酵母产生的风味物质要明显高于其他。在酱醪发酵的第15天添加T酵母使得异丁醛,乙酸乙酯,乙醇,异丁醇,正丁醇及异戊醇,乙酸含量明显提高,45天添加S酵母使HEMF的含量显著提高。表明,在酱油发酵过程中添加耐盐酵母的时间很重要,这可直接影响酱油中某些风味物质的产生及其相互的协调作用。     

Effect of ionic strength and temperature on interaction between fish myoglobin and myofibrillar proteins

ABSTRACT:  The effects of ionic strength (0, 0.3, and 0.6 M KCl) and temperature (4 and 25 °C) on the interaction between fish myoglobin and myofibrillar proteins were investigated in a model system. Increases in the relative content of bound myoglobin and metmyoglobin formation in myoglobin-natural actomyosin (NAM) mixtures with concurrent decreases in whiteness and Ca²⁺-ATPase activity were observed with increasing ionic strength ( P < 0.05). The relative content of bound myoglobin and the oxidation of oxymyoglobin were generally greater at 25 °C than at 4 °C ( P < 0.05). Binding of myoglobin to NAM resulted in decreased whiteness ( P < 0.05). Ca²⁺-ATPase was not affected by temperature ( P > 0.05). SDS-PAGE patterns of protein samples suggested that myoglobin-NAM interactions did not involve disulfide bonds. The formation of high-molecular-weight aggregates (>206 kDa) was observed and was more pronounced at higher ionic strength and higher temperature.     

TLCP/PPS 原位成纤共混纤维的非等温结晶动力学

 通过熔融纺丝法制备热致性液晶（TLCP）/聚苯硫醚（PPS）原位成纤共混纤维,TLCP微纤的形成将有效增强PPS基体的力学性能,并能优化纺丝工艺。考虑到实际纺丝过程是一个非等温结晶过程,因而首先研究了共混纤维的非等温结晶动力学行为。采用差示扫描量热仪（DSC）,通过非等温结晶方法研究了TLCP微纤对PPS基体结晶行为的影响,并用Jeziorny模型描述了非等温动力学。研究表明,TLCP/PPS原位成纤共混纤维的非等温结晶动力学过程能够使用Jeziorny模型来描述。在共混过程中,TLCP微纤结构起到异向成核的作用,提高结晶速率和结晶温度,降低半结晶时间。此外,采用扫描电镜（SEM）观察了挤出共混物表面形貌及共混纤维的TLCP微纤结构。     

反相高效液相色谱法测定雪莲果叶中的绿原酸

采用反相高效液相色谱法对雪莲果叶中的有效成分绿原酸进行分离,并对其含量进行测定,建立反相高效液相色谱法测定雪莲果叶中绿原酸含量的方法。色谱柱为Hypersil ODS-2 C18 柱(4.6mm × 300mm,5μm),流动相为乙腈- 体积分数0.5% 磷酸溶液(8:92,V/V),流速为1.0mL/min,检测波长为325nm,柱温为25℃。绿原酸在10～100μg/mL 范围内呈良好线性关系,相关系数为0.9999,加标回收率为97.0%,RSD 为1.10%。本法快速、简单、准确、分离度好,可用于实际样品的检测。     

槟榔嫩果中儿茶素的液相色谱质谱联用测定

采用甲醇超声提取槟榔嫩果中的儿茶素,先用石油醚除去杂质,再用乙酸乙酯萃取,提取物经抽真空浓缩,高效液相色谱- 质谱联用法测定。结果表明：槟榔嫩果中儿茶素类组分为(+)- 儿茶素和表没食子儿茶素没食子酸酯。