高效液相色谱法同时检测黄油及无水奶油中苯甲酸、山梨酸、安赛蜜、糖精钠

目的建立黄油及无水奶油中2种甜味剂(安赛蜜、糖精钠)及2种防腐剂(苯甲酸、山梨酸)含量的高效液相色谱分析方法。方法样品去除脂肪后,用甲醇-水(1:1,V:V)提取,提取液使用C8色谱柱(250mm×4.6 mm, 5μm)、在波长为230 nm、流动相为1.0 mL/min的条件下进行检测。结果苯甲酸、山梨酸、安赛蜜、糖精钠在0～100μg/mL范围内,浓度与峰面积有良好的线性关系,相关系数大于0.99,检出限分别为0.87、0.91、2.75、2.91 mg/kg;样品的加标平均回收率分别为93.12%～102.34%、93.02%～103.23%、91.53%～108.16%、93.48%～105.46%,相对标准偏差均小于10%。结论本方法可适用于黄油及无水奶油中苯甲酸、山梨酸、安赛蜜、糖精钠含量同时测定。     

反相高效液相色谱法同时测定黄豆酱中的苯甲酸、山梨酸、安赛蜜

建立一种用反相高效液相色谱法同时测定黄豆酱中苯甲酸,山梨酸和安赛蜜的新方法。样品经酸化后,用无水乙醚萃取,并浓缩吹干,再加入碳酸氢钠溶液溶解,样品调p H后,采用C18柱(250mm×4.6mm,5μm)分离,以甲醇(5%)+0.02mo L/L乙酸铵溶液(95%)为流动相,流速1.0m L/min,检测波长214nm(安赛蜜)及230nm(苯甲酸和山梨酸),出峰时间定性,外标法定量。结果表明:该方法的检出限为1mg/kg,线性范围为1~50μg/m L,相关系数分别为:安赛蜜R=0.99995;苯甲酸R=1.00000;山梨酸R=0.99993。回收率分别为:安赛蜜89.4%~94.1%;苯甲酸97.6%~101%;山梨酸89.6%~93.2%。相关标准偏差(RSD)分别为:安赛蜜0.38%~2.32%;苯甲酸0.26%~1.04%;山梨酸0.44%~1.82%。该方法准确方便,灵敏度高,可实现黄豆酱中苯甲酸、山梨酸、安赛蜜的测定。     

超高效液相色谱法同时测定饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜

目的建立用超高效液相色谱法(ultra performance liquid chromatography,UPLC)同时测定饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜的分析方法。方法样品中山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜用水提取,经BEH C_(18)柱(2.1 mm×100 mm,1.7μm)分离,在波长225 nm处检测。结果此方法的线性范围是5~100μg/mL,回收率为95.5%~100.2%,相对标准偏差(relative standard deviation,RSD)为1.0%~3.1%。结论此方法简便快速,准确可靠,灵敏度高,可用于同时检测饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜。     

HPLC法检测馒头中苯甲酸、山梨酸、糖精钠及安赛蜜

本试验用高效液相色谱法同时检测馒头中苯甲酸、山梨酸、糖精钠和安赛蜜。选用C18色谱柱,流动相为甲醇和20 mmol/L乙酸铵,体积比为5∶95,流速为1.0 m L/min,二级管阵列检测器检测波长为230 nm,进样量为5μL。结果表明,本方法在10.0-200 mg/L的浓度范围内线性关系良好,相关系数0.999,回收率介于88-135%之间,苯甲酸、山梨酸、糖精钠和安赛蜜的最低检出限分别为0.000 065 g/kg、0.000 015 g/kg、0.000 037 g/kg、0.000 015 g/kg。苯甲酸、山梨酸、糖精钠和安赛蜜四种物质分离较好,操作简便,有效提高了工作效率。     

双波长测定奶酪中的苯甲酸、山梨酸、糖精钠

用高效液相色谱法(HPLC)对奶酪中的苯甲酸、山梨酸、糖精钠含量进行检测分析,得到该方法中三种添加剂的检出限分别为1.0mg/kg、0.5 mg/kg、3.0 mg/kg。用空白样品进行回收率试验,苯甲酸、山梨酸、糖精钠的平均回收率分别为97.78%、98.65%、96.48%。采用氢氧化钠溶液浸泡该样品,方法操作简单、回收率高、检测快速、准确。     

高效液相色谱法同时测定蜜饯中的5种食品添加剂

采用高效液相色谱法同时测定蜜饯中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸含量的方法。试验结果表明,制备的样品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸分离良好,安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸在0.0μg~3.2μg范围内呈良好的线性关系,平均加样回收率均超过94.0%。该方法稳定性和重复性好,可作为测定蜜饯中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸的方法。     

高效液相色谱法测定黄酒中苯甲酸、山梨酸和糖精钠含量

目的建立高效液相色谱法测定黄酒中苯甲酸、山梨酸和糖精钠的分析方法。方法样品经称取、加热、定容,利用高效液相色谱法检测,甲醇水混合溶液作为流动相,PDA检测器检测,苯甲酸、山梨酸和糖精钠的检测波长为230nm。结果苯甲酸和山梨酸在0.05~0.30 mg/mL、糖精钠在0.0025~0.0125mg/mL时,都具有良好的线性关系,相关系数(r)均0.999。苯甲酸、山梨酸和糖精钠的LOD分别为1.8、1.2、0.1g/kg,LOQ分别为5.4、3.6、0.3mg/kg。平均加标回收率为95.1%~96.4%,RSD为2.6%~3.8%。50份黄酒样品中,苯甲酸检出有19份,检出率为38.0%,检测结果范围为0.0025~1.48g/kg;山梨酸检出有6份,检出率为12.0%,检测结果范围为0.028~0.44g/kg;糖精钠检出有24份,检出率为48.0%,检测结果范围为0.005~0.73g/kg。结论该方法灵敏度高,回收率高,检测限低,符合分析要求,适合黄酒中苯甲酸、山梨酸和糖精钠的检测要求。     

HPLC法同时快速测定酱油中的苯甲酸、山梨酸、糖精钠、安赛蜜

建立了一种同时快速测定酱油中苯甲酸、山梨酸、糖精钠、安赛蜜的高效液相色谱法。样品经水提取,取离心后的上清液,过0.22μm滤膜,高效色谱仪(C18柱)分析。色谱条件:色谱柱为C_(18)柱,柱温35℃,流动相为甲醇-0.02mol/L乙酸铵(体积比为5∶95),流速1.0mL/min,二极管阵列检测器检测,以保留时间定性,外标法峰面积定量。结果表明,样品在10～100mg/kg添加水平范围内,苯甲酸、山梨酸、糖精钠、安赛蜜的回收率在90%～104%,相对标准偏差小于3%。该方法简便、准确,适用于酱油中苯甲酸、山梨酸、糖精钠、安赛蜜的快速检测。     

高效液相色谱法同时检测液体食品中苯甲酸、山梨酸、安赛蜜、糖精钠含量的研究

采用高效液相色谱法同时测定液体食品中的山梨酸、苯甲酸、糖精钠、糖精钠。样品经盐酸酸化,乙醚提取,甲醇和水溶解后过HLB固相萃取小柱净化,以TC-C18(4.6×250mm,5μm)色谱柱分离。结果显示苯甲酸、山梨酸、糖精钠、安赛蜜在1.0μg/mL¹00.0μg/mL范围内呈线性关系,回收率在84.24%100.0μg/mL范围内呈线性关系,回收率在84.24%⁹6.34%之间,相对标准偏差在2.03%96.34%之间,相对标准偏差在2.03%⁴.78%之间,最低检限0.5 mg/kg,适用于同时检测液体食品中的苯甲酸、山梨酸、糖精钠、安赛蜜的含量。     

HPLC/MS测定食品中的苯甲酸、山梨酸、甜蜜素、糖精钠

建立了测定食品中苯甲酸、山梨酸、甜蜜素、糖精钠的HPLC/MS分析方法。样品中的添加剂用水提取,经HPLC分离后,在ESI负离子模式下检测。4种添加剂测定的线性范围均为10~5 000 ng/mL,检出限均优于0.1 mg/kg;各组分加标回收率分别为:苯甲酸92.1%~96.7%,山梨酸92.3%~94.4%,糖精钠94.0%~97.3%,甜蜜素95.1%~96.9%。     

烤烟中草酸、苹果酸和柠檬酸含量的分析研究

以云南、四川、河南、重庆4个烟区云烟85、K326和红大3个品种的B2L、C2L、X2L等级烟叶为材料,采用GC法测定了169个烤烟烟叶样品中草酸、苹果酸和柠檬酸的含量,并对不同产地、品种、等级和部位烤烟烟叶的多元有机酸含量进行了统计分析,结果表明:①同一地区、K326和云烟85的相同等级烤烟烟叶中草酸、苹果酸和柠檬酸含量均没有显著差异;红大和云烟85的苹果酸含量没有显著差异,而红大的草酸和柠檬酸含量均高于云烟85;②不同地区、相同品种和等级的烤烟叶中,草酸含量均没有显著性差异;苹果酸、柠檬酸含量差异显著,含量的变化趋势为:河南重庆云南和四川;③同一地区和品种、不同部位的烤烟叶中,草酸含量均为上部明显高于中部和下部,而中部和下部相当;苹果酸含量在3个部位均有较大差别,依次为:上部中部下部;柠檬酸含量下部最高,中部与上部无显著差异。     

Naturally occurring benzoic,sorbic, and propionic acid in vegetables

ABSTRACT

Benzoic, sorbic and propionic acid are used as preservatives in foods and can also be naturally present in processed foods. The levels of preservatives in 939 vegetables were determined. Benzoic and sorbic acid were analysed by high-performance liquid chromatography with a diode-array detector and further confirmed by liquid chromatography-tandem mass spectrometry, whereas propionic acid was analysed using a gas chromatography-flame ionization detector and further confirmed by gas chromatography-mass spectrometry. Benzoic and propionic acid were found in 10.9% and 36.2%, respectively, of the samples. In contrast, sorbic acid was not found in any of the samples. The highest amounts of benzoic and propionic acid were found in perilla leaves (0.33?298 mg kg^–1) and ginseng (<LOD?32.8 mg kg^–1), respectively. The background concentration ranges of naturally occurring preservatives in vegetables determined in this study could be used for inspection services of standard criteria to address consumer complaints or trade disputes.     

Anti-obesity effects of conjugated linoleic acid, docosahexaenoic acid, and eicosapentaenoic acid

Obesity has become a prevailing epidemic throughout the globe. Effective therapies for obesity become attracting. Food components with beneficial effects on "weight loss" have caught increasing attentions. Conjugated linoleic acid (CLA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) belong to different families of polyunsaturated fatty acids (PUFA). However, they have similar effects on alleviating obesity and/or preventing from obesity. They influence the balance between energy intake and expenditure; and reduce body weight and/or fat deposition in animal models, but show little effect in healthy human subjects. They inhibit key enzymes responsible for lipid synthesis, such as fatty acid synthase and stearoyl-CoA desaturase-1, enhance lipid oxidation and thermogenesis, and prevent free fatty acids from entering adipocytes for lipogenesis. PUFA also exert suppressive effects on several key factors involved in adipocyte differentiation and fat storage. Despite their similar effects and shared mechanisms, they display differences in the regulation of lipid metabolism. Moreover, DHA and EPA exhibit "anti-obesity" effect as well as improving insulin sensitivity, while CLA induces insulin resistance and fatty liver in most cases. A deeper and more detailed investigation into the complex network of anti-obesity regulatory pathways by different PUFA will improve our understanding of the mechanisms of body weight control and reduce the prevalence of obesity.     

Determination of ethanol,volatile fatty acids,lactic and succinic acids in fermentation liquids by gas chromatography

A rapid and simple quantitative method was developed to determine, by gas chromatography, the concentrations in fermentation liquids of ethanol, the C₂-C₆ volatile fatty acids, and lactic and succinic acids. Aqueous samples were acidified with 250μlml^?1 metaphosphoric acid (5:1 ratio), centrifuged, and injected directly on to a column containing a porous aromatic polymer (Chromosorb 101) maintained at 200°C in a gas chromatograph fitted with a flame ionisation detector. It was unnecessary to purify samples further before injection, although distillation and ion-exchange methods were examined. Derivatisation of lactic and succinic acids before injection was not necessary, but the lowest level of detection of these two relatively non-volatile acids was about four times greater than that for the volatile fatty acids. The method described was suitable for the analysis of rumen fluid, methane digester fluid, silage extracts and other anaerobic fermentation fluids. The relative retention times are given for 23 organic acids and six other fermentation end-products.     

气相色谱法同时快速测定食品中丙酸、山梨酸、苯甲酸及脱氢乙酸

通过液液萃取净化样品研究,建立了食品中丙酸、山梨酸、苯甲酸、脱氢乙酸及其盐含量气相色谱同时快速测定方法,适用于固体非酯(脂)类食品的检测。结果表明:丙酸的回收率在85.1%~91.3%之间,其余3种防腐剂的回收率均在95.2%~99.4%之间;实验室内变异系数(CV,n=6)最大值≤4.7%,4种防腐剂检出限均在0.002 g/kg以下。4种目标物在有杂质干扰时,可用不同的极性毛细管柱做进一步的确认。本方法具有适用范围广、检测效率高、重现性好、准确度高、检出限低的特点,推广应用对我国食品安全的监督检验具有重要的意义。     

Effects of lauric and myristic acids on ruminal fermentation, production, and milk fatty acid composition in lactating dairy cows

The objectives of this experiment were to investigate the effects of lauric (LA) and myristic (MA) acids on ruminal fermentation, production, and milk fatty acid (FA) profile in lactating dairy cows and to identify the FA responsible for the methanogen-suppressing effect of coconut oil. The experiment was conducted as a replicated 3 × 3 Latin square. Six ruminally cannulated cows (95 ± 26.4 DIM) were subjected to the following treatments: 240 g/cow per day each of stearic acid (SA, control), LA, or MA. Experimental periods were 28 d and cows were refaunated between periods. Lauric acid reduced protozoal counts in the rumen by 96%, as well as acetate, total VFA, and microbial N outflow from the rumen, compared with SA and MA. Ruminal methane production was not affected by treatment. Dry matter intake was reduced 35% by LA compared with SA and MA, which resulted in decreased milk yield. Milk fat content also was depressed by LA compared with SA and MA. Treatment had no effect on milk protein content. All treatments increased milk concentration of the respective treatment FA. Concentration of C12:0 was more than doubled by LA, and C14:0 was increased (45%) by MA compared with SA. Concentration of milk FA < C16 was 20% lower for LA than MA. Concentrations of trans 18:1 FA (except trans 12) and CLA isomers were increased by LA compared with SA and MA. Overall, the concentrations of saturated FA in milk fat were reduced, and that of > C16 FA and MUFA were increased, by LA compared with the other treatments. In this study, LA had profound effects on ruminal fermentation, mediated through inhibited microbial populations, and decreased DMI, milk yield, and milk fat content. Despite the significant decrease in protozoal counts, however, LA had no effect on ruminal methane production. Thus, the antimethanogenic effect of coconut oil, observed in related studies, is likely due to total FA application level, the additive effect of LA and MA, or a combination of both. Both LA and MA modified milk FA profile significantly.     

A method for determination of fruit-derived ascorbic, tartaric, oxalic and malic acids, and its application to the study of ascorbic acid catabolism in grapevines

Background and Aims:  The majority of the acidity of a grapevine ( Vitis vinifera L.) berry is a result of the accumulation of l -tartaric (TA) and l -malic acids (MA). TA is synthesised from l -ascorbic acid (Asc, vitamin C), the metabolism of which is poorly characterised in grapevines. In a distinct pathway, oxalic acid (OA) is also formed from Asc degradation. The aim of this study was to develop a single method whereby the distribution of Asc and its catabolites from fruit and vegetative sources could be determined.
Methods and Results:  Effective recoveries of total Asc, TA, OA and MA were achieved with this extraction method, while chromatographic separation was accomplished with reversed-phase high-performance liquid chromatography (RP-HPLC). These results demonstrate that Asc and its catabolites TA and OA rapidly accumulate in immature berries, and that the Asc to dehydroascorbate ratio increases with berry maturity.
Conclusions:  A method for the simultaneous analysis of Asc, TA, OA and MA in fruits is provided; moreover, we have demonstrated its use to study their distribution in fruits, rachis, leaves and roots.
Significance of the Study:  This method enables accurate monitoring of the accumulation of Asc, permitting further research towards understanding acid metabolism during berry ripening.     

饮料及果品中糖精、苯甲酸、山梨酸和咖啡因的反相HPLC同时快速测定

用SUPELCOSIL LC－8－DB柱为分离柱（柱温30℃）、以30：70（体积比）的甲醇：草酸铵溶液（1.25g/L)作流动相,在230nm紫外检测,反相HPLC同时快速测定了饮料和果品中的糖精、苯甲酸、山梨酸和咖啡因四种食品添加剂。在试验浓度范围2－200mg/L内均呈良好线性,它们的检出限分别为20、8、2、26ng。样品的加标回收率为104％－112％,变异系数为2．5％－4．6％（n=5）。     

气相色谱法测定鱼油中的二十碳五烯酸、 二十二碳六烯酸和二十二碳五烯酸

目的通过优化鱼油中二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的测定条件,建立鱼油中EPA、DHA和DPA气相色谱定量检测分析方法。方法采用正己烷处理样品,经色谱柱(Agilent,Elite-WAX,30 m×0.25 mm,0.25μm)分离鱼油中的EPA、DHA、DPA甲酯标准品,并进行定量检测。结果 EPA浓度在0.36~3.6 mg/m L、DHA浓度在0.37~3.7 mg/m L、DPA浓度在0.16~1.62 mg/m L的范围内与峰面积的线性良好,相关系数r0.999。在80%、100%、120%添加水平下,EPA、DHA和DPA的检出限分别为0.01%、0.03%、0.009%,EPA、DHA和DPA的回收率分别为96.2%、96.4%、95.7%。结论气相色谱法灵敏度高、准确、重现性好,适用于鱼油中EPA、DHA和DPA的含量测定。     

花生四烯酸、二十二碳六烯酸和二十碳五烯酸 在炎症中的作用概述

心脑血管疾病、肿瘤、糖尿病、神经系统疾病、自身免疫等疾病严重危害着人类的生命和健康,并消耗着大量医疗资源。事实上,很多疾病发生和发展的背后都伴随着炎症反应,炎症是众多疾病的病理基础,甚至是导致这些疾病的诱因。炎症本身是机体的防御性反应,但过度的炎症反应和长期慢性炎症会损害机体的稳态。炎症的调节和控制由炎症介质介导,花生四烯酸(arachidonic acid,AA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosapentaenoic acid,EPA)等长链多不饱和脂肪酸(10ng-chain polyunsaturated fatty acids,LC-PUFAs)的衍生物是一类重要的调控炎症的介质。炎性细胞间的交流和细胞内信号传递与LC-PUFAs有关。AA经环氧酶和脂氧合酶合成的类二十烷酸主要起促炎作用,但有的也有抗炎作用。DHA和EPA在体内起抗炎作用,由它们合成的消退素(resolvins,Rvs)和保护素(protectin,PD)是重要的抗炎活性物质。DHA和EPA还可以干扰炎性细胞内信号传导途径来抑制炎症反应。本文从炎症与疾病的关系、LC-PUFAs的衍生物及其促炎和抗炎机制等方面综述了AA、DHA和EPA在炎症中的作用。