HPLC法同时检测食品中苯甲酸、山梨酸、糖精钠及安赛蜜

建立高效液相色谱法同时检测食品中苯甲酸、山梨酸、糖精钠与安赛蜜的方法。样品经水提取、亚铁氰化钾与乙酸锌沉淀蛋白、氨水调p H值后离心处理,经Agilent ZORBAX SB-Aq色谱柱分离,甲醇与0.02 mol/L乙酸铵溶液为流动相梯度洗脱,流速为0.7 m L/min,采用二极管阵列检测器检测,波长230 nm,光谱扫描范围为200~400 nm,采用保留时间与光谱进行双重定性。在14 min内苯甲酸、山梨酸、糖精钠与安赛蜜就能够达到较好的分离,在1~100μg/m L呈良好的线性关系,线性相关系数大于0.999 8,检出限0.5~1 mg/kg,不同类别产品加标回收率在88.5%~98.4%之间,精密度5%。结果表明,该方法适用范围广、灵敏度高、准确性好,适用于各种食品中苯甲酸、山梨酸、糖精钠与安赛蜜的检测。     

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。     

超高效液相色谱法同时快速测定陈年道菜中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸

建立了一种同时快速测定陈年道菜中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸的超高效液相色谱法。样品前处理后,经Agilent Ecilpse Plus C18(50mm×2.1mm,1.8μm)色谱柱分离,以甲醇-20mmol/L乙酸铵的乙酸溶液(pH 5.28)为流动相进行梯度洗脱,采用二极管阵列检测器,检测波长为230nm,流速为0.30mL/min,柱温为40℃,以保留时间定性,外标法峰面积定量。结果表明,安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸在5min内可以完全分开,样品在0.02～0.10g/kg添加三水平范围内的回收率在66.43%～102.87%之间,相对标准偏差小于3.2%。该方法快速准确,分离效果好,适用于陈年道菜中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸的快速检测。     

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。     

高效液相色谱法检测果蔬汁中五种添加剂

目的:运用高效液色谱法对果蔬汁中苯甲酸、安赛蜜、脱氢乙酸、糖精钠以及山梨酸添加剂进行检测。方法:色谱柱:Kromasil 100-5 C18(250mm×4.6mm,5μg);流动相:甲醇∶0.02mol/L乙酰胺溶液=5∶95(V∶V);流速:1.0m L/min;进样量:20μL;柱温:30℃;波长:230nm。结果:苯甲酸、安赛蜜、脱氢乙酸、糖精钠以及山梨酸在0.00~0.1mg/m L浓度范围内,均表现为良好的线性关系(r=0.97、r=0.98、r=0.96、r=0.98、r=0.98)。山梨酸、安赛蜜、糖精钠、苯甲酸、脱氢乙酸RSD分别为1.13%、1.01%、1.51%、1.05%、1.18%;平均回收率分别为98%~99%。结论:在液果蔬汁添加剂检测中,高效液相色谱法快速准确,且灵敏度较高,可满足检查需要。     

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。     

高效液相法同时测定饮品中8种食品添加剂

首次建立同时测定饮品中8种食品添加剂(苯甲酸、山梨酸、糖精钠、安赛蜜、脱氢乙酸、咖啡因、阿斯巴甜、纳他霉素)的高效液相色谱法。试验中,样品经水溶后,加入乙酸锌与亚铁氰化钾溶液沉蛋白处理,采用C18色谱柱,以甲醇和乙酸铵溶液(0.02 mol/L)为流动相进行梯度洗脱分离,流速1.0 mL/min,测定波长210 nm和305 nm,进样量10μL。结果表明,在此条件下,8种组分得以完全分离,并呈良好线性关系,加标回收率为91%~102.5%,相对标准偏差为0.4%~2.7%。     

UPLC同时测定风味饮料中安赛蜜、糖精钠、苯甲酸、山梨酸方法研究

建立了超高效液相色谱法(UPLC)同时测定风味饮料中安赛蜜、糖精钠、苯甲酸、山梨酸4种食品添加剂检测技术.实验采用Waters ACQUITY BEH C18色谱柱(100mm ×2.1mm,1.7μm),以0.02mol/L的乙酸铵-甲醇(95:5)为流动相,柱温25℃,二极管阵列检测器在波长230nm进行检测.整个分离过程在3min内完成,HPLC检测方法至少需要12min,大大节约了检测时间.安赛蜜、糖精钠、苯甲酸、山梨酸的回收率分别为98.5%～101.3%,相对标准偏差小于0.90%.方法快速准确.     

高效液相色谱法同时测定食品中山梨酸、苯甲酸、糖精钠、安赛蜜的方法研究

采用色谱柱Shimadzu VP-ODS,150×4.6,5μm,对缓冲溶液pH,流动相各组份比例进行了研究,实现了山梨酸、苯甲酸、糖精钠、安赛蜜四种常用添加剂8分钟内同时、快速、准确检测.色谱条件为:流动相A:0.02mol/L乙酸铵溶液(pH＝6.5),B:甲醇,15%B;流速,1.2mL/min;检测波长230nm.加样回收率试验山梨酸、苯甲酸、糖精钠、安赛蜜的回收率分别为100.03%、99.75%、98.88%、101.4%,RDS＜5%.试验结果表明,此法不仅定量准确、精密度高而且操作极为方便.     

离子色谱法同时测定蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖含量

目的建立离子色谱法同时检测蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖的分析方法。方法样品用水作为提取剂,用OnGuard Ⅱ RP柱和OnGuard Ⅱ H柱净化,50mmol/LNaOH溶液作为流动相,用Carbopac PA20柱进行离子色谱分析。结果在该条件下5种糖都能得到较好分离,线性良好,葡萄糖、果糖、蔗糖、乳糖和麦芽糖的检出限为0.002、0.004、0.011、0.007、0.018 mg/L,平均回收率为90.59%～97.68%(n=9)。结论该方法操作简便、灵敏度高,可用于作为蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖的检测。     

拟穴青蟹新型过敏原肌质钙结合蛋白的纯化、鉴定及分子克隆

为进一步认识蟹类的过敏原,采用免疫印迹方法,分析发现甲壳类过敏患者血清能与拟穴青蟹肌浆蛋白中分子质量约为21 kD的蛋白质产生特异的IgE结合反应,结果显示该蛋白可能是蟹类新型过敏原。通过硫酸铵盐析、阴离子交换和凝胶过滤柱层析等方法对21 kD-蛋白进行分离纯化,采用Western blotting和基质辅助激光解析电离飞行时间质谱（matrix assisted laser desorption ionization-time of flight-mass spectrometry,MALDI-TOF-MS）确认纯化的21 kD-蛋白为肌质钙结合蛋白（sarcoplasmic calcium binding protein,SCP）。采用SMART-RACE（SwitchingMechanism At RNA Termini-Rapid Amplification of cDNA Ends）的方法获得SCP的cDNA序列,该序列全长986 bp,开放阅读框为579 bp,编码193 个氨基酸,其理论分子质量21.94 kD,等电点4.44。拟穴青蟹SCP与甲壳类动物SCP具有较高的同源性,与昆虫SCP的同源性较差;三级结构模拟分析显示,SCP含有5 个螺旋-转角-螺旋结构区,即EF-手型结构区,并在其中两个手型结构区形成2 个钙离子结合位点;进一步预测得到SCP的4 个线性抗原表位和3 个构象性抗原表位。     

Impact of transglutaminase on the textural, physicochemical, and structural properties of chicken skeletal, smooth, and cardiac muscles

This study examined the effects of microbial transglutaminase (MTG; 3.1 mg/ml) on chicken skeletal, smooth, and cardiac muscles; the meat containing the different muscle types was shaped into sausages and treated at 40 °C and/or 78 °C for 30 min. Although the three muscle types were obtained from the same bird, the effects of MTG addition were not uniform. All the muscle types showed a significant increase in the breaking strength (P < 0.01), but skeletal muscle exhibited the maximum increase. All samples showed a decrease in the fluorescence intensity and a significant reduction in the concentration of proteins that were extracted in a high ionic strength solution (P < 0.05). Scanning electron microscopy images and histological studies revealed that different muscle types had different physical structures and frameworks after MTG treatment, which is a reflection of the differences in the reaction specificity of MTG with different muscle proteins. Histological studies revealed that the reactions of MTG with meat proteins are both exogenous and endogenous. Cooking loss data suggested that MTG did not have any negative effect on water retention during cooking. MTG appears to be a functional and contributive substance since the results suggest that MTG can function on all muscle types that are mechanically processed for different industrial applications. MTG aggregates muscle proteins in different ways that improve their organoleptic properties such as texture, appearance, and water retention.     

Determination of Zn,Cu, Cd,Pb, Ni and Cr in some Slovenian foodstuffs

An acid-assisted microwave digestion procedure was optimised for the determination of trace elements in foodstuffs by the use of flame and electrothermal atomic absorption spectrometric (FAAS, ETAAS) techniques. Zn, Cu, Cd, Pb, Ni and Cr were determined in cabbage, wheat, potato, instant milk, fish, eggs and baby foodstuffs. The repeatability of measurements was tested in the cabbage sample and was found to be ±3.3% for Zn, 4.6% for Cd, ±6.8% for Cu and ±15.5% for Cr. The worse value obtained for Cr was probably due to its inhomogeneous distribution and very low concentration in the cabbage. Concentrations of Ni and Pb in the cabbage sample were below the limit of detection (0.2 mg kg^–1). The accuracy of the analytical procedure was checked by the analysis of the standard reference material CRM 1570 Trace and minor elements in spinach leaves and IAEA 336 Trace and minor elements in lichen. Good agreement between the certified or indicative and determined values was obtained. The results indicate that the concentrations of Zn, Cu, Cd, Pb, Ni and Cr found in cabbage, wheat and potato are comparable to the literature data. Cd, Pb and Ni were not found to be the contaminants in the foodstuffs analysed. Higher concentrations of Ni were found only in baby food "okolenik", arising from the cocoa that "okolenik" contained. It was demonstrated that the Cr content is very low in baby food, yolk and white of egg and in fish (<0.05 mg kg^–1 Cr). Elevated concentrations of trace elements were found only in mussels that accumulate heavy metals from the marine environment.     

Pilot survey of commercial pasteurized milk consumed in the metropolitan area of Rio de Janeiro,Brazil, for tetracyclines residues,including the 4-epimers of oxytetracycline,tetracycline and chlortetracycline

This pilot survey aimed to assess the occurrence of tetracyclines and the 4-epimers of oxytetracycline, tetracycline and chlortetracycline in commercial pasteurized milks sold in the metropolitan area of Rio de Janeiro, Brazil, between October 2009 and March 2010. A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method, developed and validated in our laboratory, was used. All 100 analyzed samples were compliant, but 14 contained oxytetracycline in concentrations ranging from the method limit of detection (3.7?µg?l^–1) to the method limit of quantification (12.2?µg?l^–1). One sample contained oxytetracycline and tetracycline simultaneously (at a concentration slightly higher than method limit of quantification, 7.0?µg?l^–1). The presence of 4-epioxytetracycline and 4-epitetracycline in contaminated samples with the parent drugs could not be confirmed as traces were detected only in the quantification MRM transition. No other tetracyclines were detected.     

超声波对低嘌呤脱脂豆浆溶解性、保水性及粘度的影响

为了研究超声波处理对低嘌呤脱脂豆浆溶解性、保水性及黏度的影响,以脱脂豆粕为原料,采用超声波法,通过单因素及正交试验,研究最佳超声波处理条件.研究结果表明,最佳超声波处理条件为超声功率315 W、超声时间40 min、超声温度60℃,此条件下的黏度为1.4 mPa·s、保水性为81.83％、溶解性为58.15％.超声波处理的溶解性比未经超声波处理提高了22.35％.因此,超声波处理能显著提高低嘌呤脱脂豆浆的溶解性及低嘌呤脱脂豆腐的保水性,降低低嘌呤脱脂豆浆的黏度.     

Bioactive compound content,antioxidant activity,deoxynivalenol and heavy metal contamination of pearled wheat fractions

Wheat kernels are rich in antioxidant compounds, that are mainly present in the outer bran layers and which are removed during milling. Unfortunately, several contaminants, e.g., mycotoxins and heavy metals, are also concentrated in the external layers. Pearling of 3 wheat varieties gave five fractions (each 5% of the original grain weight), starting from the outer layer until the inner kernel, designated as 0–5%, 5–10%, 10–15%, 15–20%, 20–25%, respectively. The remaining 75% of the inner kernel was also collected. Dietary fibre, free phenolic acids and total antioxidant activity decreased progressively from the external to the internal layers. However, the 5–10% fraction was richer in β-glucan content than the external one (0–5%). Heavy metals were only found in the most external fraction. Deoxynivalenol contamination decreased from the external to the internal layers: 64% of total contamination of kernel was found in the 0–5% and 5–10% fractions. The 10–15% kernel fraction offered the best compromise between high nutritional value and low contamination risk.     

红发夫酵母中3R,3’R-虾青素的分离纯化和结构鉴定

研究红发夫酵母中3R,3’R-虾青素的分离纯化工艺条件,并利用高效液相色谱串联大气压化学电离源质谱(high performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry,HPLCAPCI-MS)、核磁共振(nuclear magnetic resonance,NMR)和高效液相色谱-紫外光谱(high performance liquid chromatography-ultra violet,HPLC-UV)对纯化得到的虾青素结构进行鉴定。结果表明:利用细胞玻璃研磨器进行研磨提取、硅胶柱层析分离和结晶提纯相结合的方法,能够有效减少反式虾青素的异构化,得到的虾青素纯度高于95%。采用高效液相色谱-质谱仪(high performance liquid chromatography-mass spectrometry,HPLC-MS)、超导核磁共振谱仪(1H和13C NMR)以及Chiralpak IC手性固定化纤维柱分析,显示制备的反式虾青素几乎都以3R,3’R结构组成。     

Amino acids,fatty acids,and dietary fibre in edible seaweed products

The nutritional compositions of 34 edible seaweed products of the Laminaria sp., Undaria pinnatifida, Hizikia fusiforme and Porphyra sp. varieties were analyzed.