辽东湾产蛤蜊中脂肪酸组成的GC/MS分析

以无水乙醚为溶剂提取蛤蜊油,经皂化和甲酯化后利用气相色谱-质谱联用技术对其脂肪酸组成进行了分析和鉴定,共分离鉴定出15种脂肪酸,占总脂肪酸含量的89.76%。其中饱和脂肪酸的相对含量为50.77%,主要为十六烷酸(软脂酸)和十八烷酸(硬脂酸);不饱和脂肪酸的相对含量为38.99%,主要为二十碳五稀酸(EPA)、9-十六碳烯酸和11-二十碳烯酸。     

广西玉林地区八角茴香中脂肪酸的气相色谱-质谱联用分析及其对超氧阴离子自由基的抑制作用

对广西玉林地区八角茴香中的脂肪油进行提取,同时分离和鉴定其组分和含量。用索氏提取法对脂肪油进行提取,采用不同甲酯化法处理后,采用气相色谱-质谱联用技术分离和鉴定其组成和含量。研究八角茴香中脂肪酸对超氧阴离子自由基的抑制作用。主要组分为十六碳烷酸、9,12-十八碳二烯酸、9-十八碳烯酸、十八烷酸等。采用不同酯化法得到的脂肪酸主要成分基本相同,仅有较小差异,含量有一定的差异。同时测得八角茴香中脂肪酸对超氧阴离子自由基有很好的抑制作用。     

红树林植物露兜中挥发油和脂肪酸的测定

本文采用气相色谱-质谱联用分析法,测定红树林植物露兜中挥发油、脂肪酸组分及含量.结果表明:从露兜挥发油提取液中分离出76个峰,共鉴定出60种化合物,其中2,6-二叔丁基-4-甲基苯酚含量最高,达19.25%,还含有苯乙酸苯乙脂、十六酸、四十一醇、2-异丙基-5-甲基己醇、十烷醚、二十二醇、二十六醇,此外还检测出8种同分异构体;从露兜提取液中分离出22个峰,鉴定出6种脂肪酸,提取的脂肪酸以十六酸(棕榈酸)含量最高,达35.39%,十八酸含量为18.88%,9-十八碳烯酸(油酸)含量为10.03%,其中十四酸有两个同分异构体.从分析结果知,露兜叶中含有多种在食品发面有很大的应用空间的组分,值得进一步开发研究.     

野生云南肉豆蔻种子形态变异与脂肪酸组成分析

以云南省景洪市基诺乡天然林中的云南肉豆蔻种子为材料,进行种子表型性状、含油率和脂肪酸组成分析。结果表明：这一居群内22株树的种长为34.73~45.89 mm,种宽为20.36~26.54 mm,单粒重为7.67~16.86 g,种仁含油率为6.37%~15.83%;通过GC及GC-MS分析,种仁油中共检测到14种常见脂肪酸,即十二烷酸（C12∶?0）、十三烷酸（C13∶?0）、十四烷酸（C14∶?0）、十五烷酸（C15∶?0）、十六碳烯酸（C16∶?1）、十六烷酸（C16∶?0）、十七烷酸（C17∶?0）、十八碳二烯酸（C18∶?2）、十八碳烯酸（C18∶?1）、十八烷酸（C18∶?0）、二十碳烯酸（C20∶?1）、二十烷酸（C20∶?0）、二十二烷酸（C22∶?0）、二十四烷酸（C24∶?0）,其中十八碳烯酸发现位置异构现象,即C18∶?1（9）和C18∶?1（11）。十四烷酸相对含量为53.58%~62.52%,均值为58.73%,是含量最高的脂肪酸。     

红蘑、猴头菇、香菇三种食用菌中脂肪酸的气相色谱-质谱分析

采用气相色谱-质谱联用方法分别对野生红蘑、猴头菇、香菇三种食用菌中脂肪酸含量与组成进行测定、比较与分析。结果表明:野生红蘑鉴定出3种脂肪酸,其比例为十六酸13.47%,9,12-十八碳二烯酸28.30%,油酸58.23%;猴头菇签定出4种脂肪酸,其比例为十六酸24.03%,9,12-十八碳二烯酸21.85%,油酸42.40%,硬脂酸11.73%;香菇中鉴定出2种脂肪酸,其比例为十六酸11.86%,9,12-十八碳二烯酸88.14%。     

水红木油理化特性及成分分析

测定了水红木油的理化指标;用GC/MS法测定了脂肪酸组成及含量,共检出20种脂肪酸,主要成分9-十八碳烯酸(油酸)占33.34%,8,11-十八碳二烯酸占28.24%,十六烷酸(棕榈酸)占22.55%,3种脂肪酸共占84.13%;用ICP-OES法测定了矿质元素的种类和含量,检出的Ca、P、Mg、Fe、K、Mn 6种矿质元素均为人体必需元素,含量均在人体所需合理范围内.结果表明,作为一种野生植物油料资源,水红木油具有较好的研究价值和开发利用前景.     

贵州乌仁核桃果实特性及主要营养成分分析

乌仁核桃为我国西南地区特有品种,为筛选出优质乌仁核桃品种,对贵州11种乌仁核桃果实性状及主要营养成分进行测定,并分析其主要脂肪酸组成。结果表明:WR03号符合一级核桃要求;脂肪酸气质分析检测出22种脂肪酸,包括乙酸、丙酸、丁酸、辛酸、壬酸、葵酸、月桂酸、肉豆蔻酸、十五烷酸、十六碳二烯酸、十六碳烯酸、棕榈油酸、棕榈酸(软脂酸)、十七烷酸、十八碳二烯酸、亚油酸、油酸、硬脂酸、十九烷酸、二十碳烯酸、二十碳烷酸、山嵛酸,其中油酸、亚油酸、棕榈酸和硬脂酸是乌仁核桃油中的主要成分。通过分析发现本次所采乌仁核桃品质一般,未发现较优质乌仁单株。     

工业硬脂酸、油酸、芥酸、山嵛酸及其衍生物原料、用途、市场状况

<正>前言 脂肪酸天然起始原料有动物脂肪和植物油脂两大类。动物脂肪中牛油和猪油内脂肪酸组分以棕榈酸(十六碳烷酸)和硬脂酸(十八碳烷酸)含量较高(参见表1和表2)。植物油脂中菜籽油含有较多量芥酸而棕榈油含棕榈酸占40％以上(参见表3)。菜籽油中芥酸含量高低与品种有关,如甘兰型油菜,泵高芥酸品种,芥酸含量高达57.2％(参见表4)。上述四种油脂脂肪酸组分中部含有一定量油酸和亚油酸以及少量或微量其他脂肪酸。     

化学修饰GC-MS分析海马脂肪酸

以2-氨基-2-甲基丙醇(AMP)为化学修饰试剂,将不饱和脂肪酸羧基修改为含氮杂环,从而避免了链烯基中碳碳双键在EI源中的移动。以气相色谱-EI质谱分析海马脂肪酸,通过解析不饱和脂肪酸AMP化学修饰产物的EI质谱图,确定了海马脂肪酸中碳碳双键的位置,鉴定出海马中13种脂肪酸,不饱和脂肪酸相对含量为75.15%,多不饱和脂肪酸相对含量为26.17%,多不饱和脂肪酸主要为9,12-十八碳二烯酸,9,12,15-十八碳三烯酸和4,7,10,13,16,19-二十二碳六烯酸。     

中国紫苏属植物种子含油量及其脂肪酸组成研究

采用化学法萃取和GC-MS 法,对从国内5 个省、市、自治区收集的紫苏属植物5 个变种的10 份试材种子的含油率及其脂肪酸组分进行研究。结果表明,紫苏属植物10 份试材间种子的含油率介于33.49%～42.58% 之间;应用SPSS 11.0 软件对其种子含油率进行单因素方差分析,表明紫苏属植物5 个变种10 份试材间种子含油率存在极显著性差异。GC-MS 分析结果表明,紫苏属植物种子油中脂肪酸的组成简单,10 份试材种子油中共检测出6 种脂肪酸组分--棕榈酸、亚油酸、α- 亚麻酸、硬脂酸、10- 十八碳烯酸和油酸,其中前4 种为10 种试材的共有成分,1、2、3、5 号试材含油酸,但不含10- 十八碳烯酸,4、6～10 号试材含有10- 十八碳烯酸,但不含油酸。10 份试材种子油中α- 亚麻酸含量介于71.75%～80.06% 之间,不饱和脂肪酸的含量介于88.80%～92.82% 之间。     

Novel genomic tools for specific and real-time detection of biothreat and frequently encountered foodborne pathogens

The bacterial genera Escherichia, Salmonella, Shigella, Vibrio, Yersinia, and Francisella include important food safety and biothreat agents. By extensive mining of the whole genome and protein databases of diverse, closely and distantly related bacterial species and strains, we have identified novel genome regions, which we utilized to develop a rapid detection platform for these pathogens. The specific genomic targets we have identified to design the primers in Francisella tularensis subsp. tularensis, F. tularensis subsp. novicida, Shigella dysenteriae, Salmonella enterica serovar Typhimurium, Vibrio cholerae, Yersinia pestis, and Yersinia pseudotuberculosis contained either known genes or putative proteins. Primer sets were designed from the target regions for use in real-time PCR assays to detect specific biothreat pathogens at species or strain levels. The primer sets were first tested by in silico PCR against whole-genome sequences of different species, subspecies, or strains and then by in vitro PCR against genomic DNA preparations from 23 strains representing six biothreat agents (Escherichia coli O157:H7 strain EDL 933, Shigella dysenteriae, S. enterica serovar Typhi, F. tularensis subsp. tularensis, V. cholerae, and Y. pestis) and six foodborne pathogens (Salmonella Typhimurium, Salmonella Saintpaul, Shigella sonnei, F. tularensis subsp. novicida, Vibrio parahaemolyticus, and Y. pseudotuberculosis). Each pathogen was specifically identifiable at the genus and species levels. Sensitivity assays performed with purified DNA showed the lowest detection limit of 128 fg of DNA/μl for F. tularensis subsp. tularensis. A preliminary test to detect Shigella organisms in a milk matrix also enabled the detection of 6 to 60 CFU/ml. These new tools could ultimately be used to develop platforms to simultaneously detect these pathogens.     

槟榔油的分离及GC-MS 分析

采用硅胶柱层析、气相色谱- 质谱(GC-MS)联用方法对槟榔油进行分离纯化和成分分析,确定以正已烷-丙酮(8:2,V/V)体系作为槟榔油分离的洗脱液。分离纯化后的槟榔油经GC-MS 测定共有18 种脂肪酸,其中含量较高的有十四烷酸(肉豆蔻酸)26.08%、十八碳烯酸(油酸)24.20%、十八碳二烯酸(亚油酸)22.70%、十六烷酸(棕榈酸)14.09% 和十二烷酸(月桂酸)7.87%。可见,槟榔油可开发为具有调节血脂、延缓衰老的保健食品。     

农产品中食源性致病菌的污染状况分析

目的了解农产品中食源性致病菌的污染状况,为政府监管提供依据。方法共抽取430份农产品样品,监测项目为沙门氏菌、单核细胞增生李斯特氏菌、金黄色葡萄球菌、大肠埃希氏菌O157:H7、霍乱弧菌、志贺氏菌、副溶血性弧菌和诺如病毒。采用全自动基因指纹分析仪对分离到的部分沙门氏菌和金黄色葡萄球菌株进行核糖体基因指纹鉴定。结果农产品中存在食源性致病菌的污染,畜禽产品中检出单核细胞增生李斯特氏菌22株、沙门氏菌17株、金黄色葡萄球菌7株;水产品中检出霍乱弧菌7株;鲜食蔬菜中检出金黄色葡萄球菌11株,72%的金黄色葡萄球菌产肠毒素。全自动基因指纹分析仪的鉴定结果和国标方法完全一致。结论应重视农产品的源头污染,加强监控。全自动基因指纹分析仪可用于食源性致病菌的快速鉴定和溯源。     

槐花精油的化学成分及其抑菌活性的研究

采用同时蒸馏萃取法提取槐花精油,用气相-质普联用技术(GC-MS)分析其化学成分;鉴定出43种化合物,占出峰总面积的98.49 %;主要成分为十六酸(38.69%)、亚油酸甲酯(10.13%)、2-甲氧基-4-(2-丙烯基)-苯酚(6.71%)、亚麻酸(6.35%)、2-羟基-3-甲基-4H-吡喃-4-酮(3.49%)、8-十七碳烯(2.44%)、二苯砜(2.44%)、6,10,14-三甲基-2-十五酮(1.85%)、4-乙烯基-2-甲氧基苯酚(1.82%)等.体外抑菌实验显示该精油对金黄色葡萄球菌ATCC 6538、伤寒沙门氏菌CMCC50013、志贺氏痢疾杆菌CMCC51334、埃希氏大肠杆菌ATCC 8099均有抑制作用.     

广式腊肉风味物质成分分析的研究

采用固相微萃取-气相色谱-质谱(SPME-GC-MS)联用技术分析了广式腊肉的挥发性风味物质,并对风味提取物质进行了鉴定.结果表明,从广式腊肉检测出的10种挥发性风味物质中酯类物质占75.45%;优质广式腊肉中不饱和脂肪酸含量(56.60%)高于饱和脂肪酸含量(43.40%),主要脂肪酸是十八碳烯酸、十六烷酸及硬脂酸;变质腊肉不饱和脂肪酸含量为54.75%.饱和脂肪酸为45.25%,相对于优质广式腊肉,不饱和脂肪酸舍量减少,而饱和脂肪酸增加;广式腊肉的劣变原因之一是由不饱和脂肪酸氧化生成饱和脂肪酸,以致产生异味而造成的.     

聚合酶链式反应-变性高效液相色谱法检测5种食源性致病菌

目的建立聚合酶链式反应与变性高效液相色谱(polymerase chain reaction-denaturing high-performanceliquid chromatography,PCR-DHPLC)相结合的方法,快速检测5种食源性致病菌(沙门菌、副溶血性弧菌、福氏志贺菌、大肠埃希菌O157∶H7和单核细胞增生李斯特菌)。方法针对16S rRNA基因保守区设计引物,PCR扩增产物用变性高效液相色谱仪检测,并进行敏感性、特异性、检出率等指标测定。结果柱温61.4℃时,5种致病菌PCR产物分别呈现特异DHPLC色谱图,保留时间均为7min左右。对沙门菌、副溶血性弧菌和单核细胞增生李斯特菌检出限均为5～10CFU/ml,福氏志贺菌和大肠埃希菌O157∶H7均为1～5CFU/ml。对83株目的分离株的检出符合率为100%,38株非目的分离株检测均为阴性;对人工污染食品中的5种致病菌均可正确检出。结论该PCR-DHPLC方法具有较高的敏感性和特异性,可用于食品中5种食源性致病菌的高通量快速检测。     

Advanced gas chromatographic-mass spectrometric studies for identification of the cellular octadecenoate isomers and changes of fatty acid composition induced by ethanol stress in Escherichia coli and Escherichia coli O157: H7

Ethanol can be introduced to foods of various origins and is commonly used for surface disinfection. Low concentrations of residual ethanol may provide an opportunity for pathogens to adapt and grow. Change of cellular fatty acid composition is one of adaptation mechanisms enabling bacteria to grow under varied stresses. Since instrumental analyses of bacterial octadecenoate isomers are sophisticated, gas chromatographic analyses of the isomers, namely trans-9-octadecenoate, trans-11-octadecenoate, cis-9-octadecenoate, and cis-11-octadecenoate, and ethanol-induced formation of trans-9-octadecenoate in Escherichia coli and E. coli O157:H7 were intensively investigated. When an HP-1, a nonpolar capillary column, was used for gas chromatographic analyses of 28 authentic bacterial acid methyl esters, resolution was satisfied for all fatty acid components except trans-9-octadecenoate and cis-11-octadecenoate, being overlapped. When the column was replaced by an RTx-2330, a polar capillary column, all of the above-mentioned octadecenoate isomers were resolved. When cells of E. coli and E. coli O157:H7 were harvested after submerged cultivation (30 degrees C, 150 rpm) in tryptic soy broth and tryptic soy broth supplemented with 5% ethanol at early stationary phase and subjected to cellular fatty acid analyses by using an HP-1 and RTx-2330 coupled with a mass detector, 12 fatty acids, i.e., trans-9-octadecenoate, 5 saturated fatty acids, 2 cyclopropane fatty acids and 4 cis-unsaturated fatty acids, were identified. Individual fatty acid contents varied depending on nature of fatty acid, strain of E. coli, and supplement of ethanol. As affected by ethanol stress for both E. coli strains, contents of trans-9-octadecenoate increased, whereas contents of cyc-9,10-methylene octadecanoate (cyc-9,10-19:0) decreased significantly (P < 0.05). Apparently, both E. coli strains have rendered necessary fatty acid adaptation to survive and grow under ethanol stress.     

Selectivity and specificity of a chromogenic medium for detecting Vibrio parahaemolyticust

The thiosulfate-citrate-bile salts-sucrose agar (TCBS) used in the most-probable-number method for detecting Vibrio parahaemolyticus cannot differentiate growth of V. parahaemolyticus from Vibrio vulnificus or Vibrio mimicus. This study examined the selectivity and specificity of Bio-Chrome Vibrio medium (BCVM), a chromogenic medium that detects V. parahaemolyticus on the basis of the formation of distinct purple colonies on the medium. A panel consisting of 221 strains of bacteria, including 179 Vibrio spp. and 42 non-Vibrio spp., were examined for their ability to grow and produce colored colonies on BCVM. Growth of Salmonella, Shigella, Escherichia coli, Enterobacter cloacae, Yersinia enterocolitica, and Aeromonas was inhibited by both BCVM and TCBS. All 148 strains of V. parahaemolyticus grew on BCVM, and 145 of them produced purple colonies. The remaining 31 Vibrio spp., except one strain of Vibrio fluvialis, were either unable to grow or produced blue-green or white colonies on BCVM. Bio-Chrome Vibrio medium was capable of differentiating V. parahaemolyticus from other species, including V. vulnificus and V. mimicus. Further studies are needed to evaluate the sensitivity and specificity of BCVM for detecting V. parahaemolyticus in foods.     

Antibacterial activity directed isolation of compounds from Punica granatum

ABSTRACT:  Chemical investigation of the methanolic extract of pomegranate fruit following antibacterial activity directed isolation led to the isolation of pelargonidin-3-galactose, cyanidin-3-glucose, gallic acid, quercetin, and myricetin. All these compounds exhibited substantial activity against species of corynebacteria, staphylococci, streptococci, Bacillus subtilis , Shigella , Salmonella , Vibrio cholera , and Escherichia coli . However, all these compounds were more active against Gram-positive species. On comparing the activity of all the isolated pure compounds, it was found that gallic acid showed the highest antibacterial activity against all the tested sensitive strains and the activity of the remaining pure compounds was almost same due to the structural similarities of the compounds. The reason for antibacterial activity of all pure compounds was attributed to their phenolic structure.     

Lactobacillus fermentum isolated from human colonic mucosal biopsy inhibits the growth and adhesion of enteric and foodborne pathogens

A number of Lactobacillus species are used as probiotic strains in order to benefit health. We have isolated L. fermentum from human colonic mucosal biopsy samples that possess antimicrobial activities against entroinvasive and foodborne pathogens such as Escherichia coli, Salmonella paratyphi A, Shigella sonnei, Staphylococcus aureus, Enterococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa, and Vibrio sp. In addition to lactic acid, L. fermentum secretes antimicrobial proteinacious compound(s) that was found to be active even at neutral pH (pH 7.0). The compound was sensitive to heat treatment and trypsin digestion. Lactobacillus fermentum inhibited the adhesion of enteropathogens to intestinal epithelial cells in vitro. Isolated cell surface associated proteins (SAPs) from L. fermentum were sufficient for the adhesion exclusions of enteropathogenic E. coli. Our results indicate that L. fermentum produces antimicrobial compounds and SAPs to inhibit the growth and adhesion of enteropathogens, respectively.