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Population estimates of folate intake from food analyses

AMERICAN JOURNAL OF CLINICAL NUTRITION 2002年第3期76卷 689-690页

作者： Kariluoto, S Vahteristo, LT Finglas, PM de Meer, K Nau, H Kehlenbach, U Univ Helsinki Dept Appl Chem & Microbiol FIN-00014 Helsinki Finland Food Res Inst Norwich Norfolk England Vrije Univ Amsterdam Ctr Med Dept Clin Chem Amsterdam Netherlands Sch Vet Med Dept Food Toxicol Hannover Germany

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Liquid chromatographic determination of residual nitrite/nitrate in foods:: NMKL collaborative study

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JOURNAL OF AOAC INTERNATIONAL 2000年第2期83卷 365-375页

作者： Merino, L Edberg, U Fuchs, G Åman, P Natl Food Adm Chem Div 2 S-75126 Uppsala Sweden Swedish Univ Agr Sci S-75007 Uppsala Sweden

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%, Repeatability and reproducibility were satisfactory.

关键词：阴离子色谱法离子交换/方法色谱法液相/方法乳制品/分析欧洲食品添加剂/分析食品分析/方法氢离子浓度肉/分析硝酸盐类/分析亚硝酸盐类/分析质量控制结果可重复性敏感性与特异性分光光度法/方法蔬菜/化学

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Immunoaffinity column cleanup with liquid chromatography using post-column bromination for determination of aflatoxins in peanut butter, pistachio paste, fig paste, and paprika powder:: Collaborative study

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JOURNAL OF AOAC INTERNATIONAL 2000年第2期83卷 320-340页

作者： Stroka, J Anklam, E Jörissen, U Gilbert, J Commiss European Communities Joint Res Ctr Inst Hlth & Consumer Protect Food Anal Unit I-21020 Ispra VA Italy Dr Wierz Dr Jorissen GmbH D-21107 Hamburg Germany Minist Agr Fisheries & Food Cent Sci Lab York YO41 1LZ N Yorkshire England

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B-1 and total aflatoxins at European regulatory limits. The test portion is extracted with methanol-water (8 + 2) for dried figs and paprika, and with methanol-water (8 + 2) plus hexane (or cyclohexane) for peanut butter and pistachios. The sample extract is filtered, diluted with phosphate buffer saline, and applied to an immunoaffinity column. The column is washed with water and the aflatoxins are eluted with methanol. Aflatoxins are quantitated by reversed-phase LC with post-column derivatization (PCD) involving bromination. PCD is achieved with either an electrochemical cell (Kobra cell) and addition of bromide to the mobile phase or pyridinium hydrobromide perbromide. Determination is by fluorescence. Peanut butter, pistachio paste, dried fig paste, and paprika powder samples, both naturally contaminated with aflatoxins and containing added aflatoxins, were sent to 16 collaborators in 16 European countries. Test portions of samples were spiked at levels of 2.4 and 9.6 ng/g for total aflatoxins which included 1.0 and 4.0 ng/g aflatoxin B-1, respectively. Recoveries for total aflatoxins ranged from 71 to 92% with corresponding recoveries for aflatoxin B-1 of 82 to 109%. Based on results for spiked samples (blind duplicates at 2 levels) as well as naturally contaminated samples (blind duplicates at 4 levels, including blank), the relative standard deviation for repeatability ranged from 4.6 to 23.3% for total aflatoxins and from 3.1 to 20.0% for aflatoxin B-1. The relative standard deviation for reproducibility ranged from 14.1 to 34.2% for total aflatoxins, and from 9.1 to 32.2% for aflatoxin B-1. The method showed acceptable within-laboratory and between-laboratory precision for all 4 matrixes, as evidenced by HORRAT values <1, at the low levels of determination for both total aflatoxins and af

关键词：黄曲霉毒素B1/分析黄曲霉毒素类/分析溴辣椒属/化学色谱法亲和色谱法高压液相/方法食品分析/方法食品污染水果/化学免疫测定指示剂和试剂坚果/化学植物药用结果可重复性敏感性与特异性

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Relationship of (known) control values to (unknown) test values in proficiency studies of pesticide residues

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JOURNAL OF AOAC INTERNATIONAL 2000年第2期83卷 399-406页

作者： Horwitz, W Wood, R US FDA Washington DC 20204 USA MAFF Norwich NR4 7UQ Norfolk England

Proficiency studies have been suggested as an alternative source of information for evaluating method performance characteristics when results from interlaboratory method performance studies conforming to internationally recognized protocols are not available. To explore this possibility, results were examined from ongoing proficiency studies of pesticide residue analyses in celery, carrot, and grape purees, and in wine. Statistical performance parameters were calculated from 18 data sets analyzed as unknowns by about 60 analysts for 12 analytes in the 25-1000 mu g/kg range, and from presumably parallel control (spike) analyses conducted by about half of the participants. A surprising finding was that recovery of known, independent control additions by the participant did not correlate with the recoveries determined as unknowns in the exercise. The data suggest that censoring or truncating of control data has occurred. The question of substitution of proficiency data for method performance data cannot be answered until the problem of unbiased reporting of control data is resolved.

关键词：伞形科/化学色谱法气相色谱法高压液相胡萝卜/化学食品分析/方法食品分析/标准食品分析/统计学和数值数据食品污染水果/化学农药残留量/分析质量控制噻苯哒唑/分析葡萄酒/分析

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Determination of inulin in foods

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JOURNAL OF AOAC INTERNATIONAL 2000年第3期83卷 675-678页

作者： Simonovska, B Natl Inst Chem Food Chem Lab SI-1000 Ljubljana Slovenia

A method was developed for determining fructan inulin in various foods (yogurts, honey cakes, chocolates). Warm water was applied for extraction of samples, and mono- and dissacharides were determined by a thin-layer chromatographic densitometric method. A portion of the test solution was hydrolyzed 30 min with 1% oxalic acid in a boiling water bath. Fructose was determined in the hydrolysate. The amount of inulin in a sample was calculated as the difference between the amount of fructose in the sample before and after hydrolysis. The fructose from sucrose formed during the hydrolysis was also considered. The mean recovery from yogurt fortified with 4% inulin was 95.5 +/- 4.5% (mean +/- standard deviation);from honey cakes extract fortified with 10% inulin, 97.3 +/- 5.5%;and from chocolate extract fortified with 30% inulin, 98.6 +/- 6.6% (6 replicates in all cases). Determination of glucose is not necessary for analyzing fructans with the composition expressed shortened to GF(n-1) (G, glucose;F, fructosyl) with the average degree of polymerization 8 less than or equal to n less than or equal to 15.

关键词：可可树/化学色谱法薄层食品分析/方法果糖/分析蜂蜜热温度水解作用菊糖/分析乳/化学酸乳/分析动物

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Measurement of total fructan in foods by enzymatic/spectrophotometric method: Collaborative study

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JOURNAL OF AOAC INTERNATIONAL 2000年第2期83卷 356-364页

作者： McCleary, BV Murphy, A Mugford, DC Megazyme Int Ireland Ltd Bray Wicklow Ireland BRI Australia Ltd N Ryde NSW 2113 Australia

An AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measuring oligofructans and fructan polysaccharide (inulins) in mixed materials and food products. The sample is extracted with hot water, and an aliquot is treated with a mixture of sucrase (a specific sucrose-degrading enzyme), alpha-amylase, pullulanase, and maltase to hydrolyze sucrose to glucose and fructose, and starch to glucose. These reducing sugars are then reduced to sugar alcohols by treatment with alkaline borohydride solution. The solution is neutralized, and excess borohydride is removed with dilute acetic acid. The fructan is hydrolyzed to fructose and glucose using a mixture of purified exo- and endo-inulinanases (fructanase mixture). The reducing sugars produced (fructose and glucose) are measured with a spectrophotometer after reaction with para-hydroxybenzoic acid hydrazide. The samples analyzed included pure fructan, chocolate, low-fat spread, milk powder, vitamin tablets, onion powder, Jerusalem artichoke flour, wheat stalks, and a sucrose/cellulose control flour. Repeatability relative standard deviations ranged from 2.3 to 7.3%;reproducibility relative standard deviations ranged from 5.0 to 10.8%.

关键词：氢硼化物酶类食品分析/方法果聚糖类/分析糖苷水解酶类/代谢水解作用指示剂和试剂菊糖/分析质量控制溶液分光光度法/方法蔗糖酶/代谢 α淀粉酶类/代谢 α葡糖苷酶类/代谢

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New method for determining total dietary fiber by liquid chromatography

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JOURNAL OF AOAC INTERNATIONAL 2000年第4期83卷 1013-1019页

作者： Ohkuma, K Matsuda, I Katta, Y Tsuji, K Matsutani Chem Ind Co Ltd Itami Hyogo 6648508 Japan Himeji Inst Technol Sch Human Environm Policy & Technol Lab Environm Life & Living Himeji Hyogo 6700092 Japan

The molecular weight limit of water-soluble dietary fiber (SDF) determined by the Prosky method was studied by liquid chromatography (LC), It was confirmed that only SDF with an average degree of polymerization of 12 or higher can be determined by the Prosky method. Total dietary fiber (TDF) was determined by 2 additional methods using LC, In the first method, the total quantity of insoluble dietary fiber (IDF) and high molecular weight SDF (HMSDF) was determined according to the modified Prosky method (MES-TRIS buffer-based). The quantitatively collected final filtrate was analyzed by LC for the quantity of low molecular weight SDF (LMSDF), and the 2 quantities were totaled to obtain TDF, TDF values thus determined for rice, polished or unpolished, soybean flour, and pressed barley were higher than those determined by the Prosky method by approximately 6, 3.5, and 3.5%, respectively. In the second method, direct determination by LC analysis was done on samples after enzymatic treatment according to the Prosky method. Results showed that the determination of LMSDF, in particular, was highly accurate and more effective. In both of these methods, the quantity of LMSDF was determined from its chromatographic peak area ratio to glucose as an internal standard, which was produced by hydrolysis.

关键词：碳水化合物/分析化学分馏法色谱法液相/方法膳食纤维/分析内肽酶类/代谢乙醇食品分析/方法葡聚糖1 4-α-葡糖苷酶/代谢大麦属/化学热温度水解作用分子量溶解度黄豆/化学水 α淀粉酶类/代谢

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Validation of an immunoassay for detection and quantitation of a genetically modified soybean in food and food fractions using reference materials: Interlaboratory study

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JOURNAL OF AOAC INTERNATIONAL 2000年第4期83卷 919-927页

作者： Lipp, M Anklam, E Stave, JW Commiss European Communities Joint Res Ctr Inst Hlth & Consumer Protect Food Prod & Consumer Goods Unit I-21020 Ispra Italy Strateg Diagnost Inc Newark DE 19702 USA

An immunoassay for detection of a specific genetically modified soybean (Roundup-Ready(R)) was validated on dried soybean powder in an interlaboratory study. Different percentages of genetically modified soybeans in nonmodified soybean matrix were evaluated in a blind study. Thirty-eight laboratories from 13 countries participated, The immunoassay was evaluated for 2 end-points: (1) To give a semiquantitative result, i.e., determination of a given sample above or below a given threshold, or (2) to compute a quantitative result, i.e., percentage of genetically modified soybeans in the sample. Semiquantitative results showed that a given sample which contained <2% genetically modified soybeans was identified as below 2% with a 99% confidence level. Quantitative use of the assay resulted in a repeatability (r) and reproducibility (R) that were computed to be RSDr = 7% and RSDR = 10%, respectively, for a sample containing 2% genetically modified soybeans. Application of this method depends on availability of appropriate reference materials for a specific food matrix. Only matrix-matched reference materials can be used for analysis of food or food fractions.

关键词：抗体单克隆校准食品分析/方法遗传工程免疫测定国际合作实验室 Logistic模型质量控制试剂盒诊断参考标准敏感性与特异性黄豆/化学黄豆/遗传学

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Determination of egg proteins in food products by enzyme immunoassay

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JOURNAL OF AOAC INTERNATIONAL 2000年第1期83卷 139-143页

作者： Yeung, JM Newsome, WH Abbott, MA Natl Food Proc Assoc Washington DC 20005 USA Hlth Canada Hlth Protect Branch Food Directorate Bur Chem SafetyFood Res DivPL Ottawa ON K1A 0L2 Canada

An enzyme-linked immunosorbent assay (ELISA) was developed to determine the presence of egg proteins in foods. The polyclonal antibodies developed were specific to whole egg proteins and did not cross-react with any of the 38 nuts, legumes, or other common food ingredients tested, The concentrations of egg proteins that will inhibit 50% of antibody-antigen binding, IC50, were 3-7 ng/mL, and the linear range was 0.5-62.5 ng/mL. The detection limit was 0.2 ppm for various foods. Recoveries ranged from 67 to 96%, The intra- and inter-assay coefficients of variation in this procedure were 10-13% for ice cream spiked at 0.8 and 1.6 ppm, The ELISA has been applied to ice creams, noodles, pasta, and breads, Egg proteins were identified in all declared egg products, and no false positives were found.

关键词：抗体特异性面包/分析卵蛋白质类/分析酶联免疫吸附测定/方法食品分析/方法热温度冰淇淋/分析蛋白质变性质量控制结果可重复性敏感性与特异性

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Determination of low levels of mite and insect contaminants in food and feedstuffs by a modified flotation method

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JOURNAL OF AOAC INTERNATIONAL 2000年第1期83卷 113-119页

作者： Thind, BB Minist Agr Fisheries & Food Cent Sci Lab York N Yorkshire England

Extraneous material was separated from feed and food products by a modified technique in which kerosene is used in a specially designed flotation flask. This technique, although effective for analyzing feed and foods, presented limitations in the analysis of finely powdered materials. Some procedural modifications and an increased in the capacity of the flotation flask from 500 to 750 mt allowed a larger sample weight (20 g) to be analyzed for mites, insect fragments, and rodent hairs, with considerably reduced residue interference. In trials with a variety of products seeded with known numbers of mites, average recovery was 83%. Recoveries of 89% were obtained from flour samples seeded with insect fragments and rodent hairs, A new process of suspending extracted mites in a mixture of industrial methylated spirit (46%) and glycerol (54%) by volume was used to allow rapid and more precise estimates of mite populations in heavily infested samples.

关键词：动物饲料食品分析/仪器和设备食品分析/方法食品污染毛发指示剂和试剂煤油螨啮齿目动物

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