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  • 1. Finglas, P M
    et al.
    Wigertz, K
    Vahteristo, L
    Witthöft, Cornelia M.
    Institute of Food Research, Norwich Research Park, UK.
    Southon, S
    de Froidmont-Gortz, I
    Standardisation of HPLC techniques for the determination of naturally-occurring folates in food1999In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 64, no 2, p. 245-255Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to evaluate current in-house HPLC procedures for the determination of naturally-occurring folates in food, and to identify problem areas for further improvement. Five intercomparison studies were completed over the period 1990-1997 in which nine participants from six countries took part. Through careful validations and detailed discussions held at evaluation meetings, possible biases and sources of systematic error have been identified and reduced. The use of ascorbic acid and nitrogen flushing during extraction, sample clean-up using strong anion exchange columns, spectrophometrically calibrated standards and fluorescence detection are all recommended. Both in-house hog kidney and human plasma deconjugase enzymes gave similar results to the circulated common hog kidney enzyme which was prepared from fresh pig's kidneys. The most consistently reported values were for 5-CH3H4-PteGlu, and to a lesser extent, for H(4)PteGlu. Four candidate reference materials (CRM 121, wholemeal flour; CRM 421, milk powder; CRM 485, lyophilised mixed vegetables, and CRM 487, lyophilised pig's liver) have been proposed with both indicative values (mean +/- uncertainty) for 5-CH3H4-PteGlu in CRM 421 (0.25; +/- 0.02 mg/kg) and CRM 485 (2.14; +/- 0.42 mg/kg), and information values (mean; range) for 5-CH3H4-PteGlu in CRh4 121 (0.04; 0.03-0.08 mg/kg) and CRM 487 (2.6; 1.9-3.8 mg/kg), Certified values are also given for total folate by microbiological assay: CRM 121 (0.50; +/- 0.07 mg/kg), CRM 421 (1.42; +/- 0.14 mg/kg), CRM 485 (3.15; 0.28 mg/kg), and CRM 487 (13.4; 1.3 mg/kg). Average recovery of 5-CH3H4-PteGlu, added prior to extraction and deconjugation, was 91% (84-95%) for the four CRMs. The average within- and between-laboratory variations were 6 and 15% for the determination of 5-CH3H4-PteGlu by HPLC, and 9 and 18% for the determination of total folate by microbiological assay. These CRMs will be used for quality control of folate measurements for nutritional labelling, and validation of new techniques. Further methodology work is required for the HPLC analyses of folate forms other than 5-CH3H4-PteGlu. 

  • 2.
    Hefni, Mohammed E.
    et al.
    Swedish Univ Agr Sci ; Mansoura Univ, Egypt.
    Öhrvik, Veronica
    Swedish University of Agricultural Sciences.
    Tabekha, Mohamed
    Mansoura Univ, Egypt.
    Witthöft, Cornelia M.
    Swedish University of Agricultural Sciences.
    Folate content in foods commonly consumed in Egypt2010In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 121, no 2, p. 540-545Article in journal (Refereed)
    Abstract [en]

    The folate content in some Egyptian foods was determined using RP-HPLC-FL. Trienzyme treatment was used for legumes, dienzyme treatment for cereals and starchy vegetables, and monoenzyme treatment for vegetables and fruits. The highest folate content (633 mu g/100 g) was found in dried Jew's mellow due to low water content, followed by legumes (e.g. 150 mu g/100 g for chick peas) and leafy vegetables (100 mu g/100 g). For other foods, folate content ranged from 10-90 mu g/100 g. In all foods, the predominant folate form was 5-CH(3)-H(4)folate, except for dried Jew's mellow, which contained more than 80% 10-HCO-PteGlu. Using folate data from our own analyses and food tables and food consumption data, the dietary folate intake per capita in Egypt was estimated. However, representative and validated food composition data for folate in Egyptian foods are needed for estimating and evaluating the adequacy of the population's folate intake. (C) 2009 Elsevier Ltd. All rights reserved.

  • 3.
    Hollman, Peter C. H.
    et al.
    RIKILT Inst Food Safety, Netherlands ;Wageningen Univ, Netherlands.
    Witthöft, Cornelia M.
    Swedish University of Agricultural Sciences.
    Busstra, Maria C.
    Wageningen Univ, Netherlands.
    Elburg, Lucy
    Wageningen Univ, Netherlands.
    Hulshof, Paul
    Wageningen Univ, Netherlands.
    Training aspects in the use and production of food composition databases. The EuroFIR experience2009In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 113, no 3, p. 842-845Article in journal (Refereed)
    Abstract [en]

    An increasing number of national food databases have been published on the internet. However, these internet databases can only be searched individually, and the data have been compiled at a national level, resulting in incompatibilities. To resolve these problems, the Network of Excellence EuroFIR develops an internet based platform for online access to various national authoritative sources of food composition data in Europe. Training is essential for its use, and for the development of harmonised procedures of data production, evaluation, compilation, and retrieval. The training program developed within EuroFIR consists of individual training, supported by exchange grants, and a collection of workshops and training courses. Supportive E-learning modules are under construction. Procedures for the evaluation of each training activity have been made to measure its efficacy, and to learn about new training needs. Attention is given to special training needs of compilers in central and eastern European countries. (C) 2008 Elsevier Ltd. All rights reserved.

  • 4.
    Jastrebova, Jelena
    et al.
    Swedish University of Agricultural Sciences.
    Witthöft, Cornelia M.
    Swedish University of Agricultural Sciences.
    Grahn, Anders
    ChromTech.
    Svensson, Ulla
    Procordia Food.
    Jagerstad, Margaretha
    Swedish University of Agricultural Sciences.
    HPLC determination of folates in raw and processed beetroots2003In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 80, no 4, p. 579-588Article in journal (Refereed)
    Abstract [en]

    A sensitive HPLC method with fluorescence detection and gradient elution has been developed for the determination of folates in vegetables. The method involved extraction of folates from food matrix by heat treatment, deconjugation of folate polyglutamates to monoglutamates by incubation with hog kidney conjugase and purification of food extracts by solid-phase extraction with strong-anion exchange cartridges. The chromatographic separation of folates was achieved on Zorbax SB C-8 column, which was found to be superior over conventional C-18 column in terms of selectivity and sensitivity. Validation of the method included linearity tests, the addition of standard folates for the determination of recovery, repeatability and stability tests. The method developed was applied to analysis of raw and processed beetroots; 5-methyltetrahydrofolate was found to be the main folate form in beetroots. Cultivar differences and growing conditions were found to have a pronounced effect on the folate content in beetroots. Processing resulted in considerable losses of folates, whereas losses during storage appeared to be moderate.

  • 5.
    Nicolas, Geneviève
    et al.
    International Agency for Research on Cancer, France.
    Witthöft, Cornelia M.
    Swedish University of Agricultural Sciences, Uppsala.
    Vignat, Jérôme
    International Agency for Research on Cancer, France.
    Knaze, Viktoria
    International Agency for Research on Cancer, France.
    Huybrechts, Inge
    International Agency for Research on Cancer, France.
    Roe, Mark
    Institute of Food Research, Norwich Research Park, UK.
    Finglas, Paul
    Institute of Food Research, Norwich Research Park, UK.
    Slimani, Nadia
    International Agency for Research on Cancer, France.
    Compilation of a standardised international folate database for EPIC.2016In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 193, p. 134-140Article in journal (Refereed)
    Abstract [en]

    This paper describes the methodology applied for compiling an "international end-user" folate database. This work benefits from the unique dataset offered by the European Prospective Investigation into Cancer and Nutrition (EPIC) (N=520,000 subjects in 23 centres). Compilation was done in four steps: (1) identify folate-free foods then find folate values for (2) folate-rich foods common across EPIC countries, (3) the remaining "common" foods, and (4) "country-specific" foods. Compiled folate values were concurrently standardised in terms of unit, mode of expression and chemical analysis, using information in national food composition tables (FCT). 43-70% total folate values were documented as measured by microbiological assay. Foods reported in EPIC were either matched directly to FCT foods, treated as recipes or weighted averages. This work has produced the first standardised folate dataset in Europe, which was used to calculate folate intakes in EPIC; a prerequisite to study the relation between folate intake and diseases.

  • 6.
    Pavlovic, Mirjana
    et al.
    Univ Belgrade, Serbia.
    Witthöft, Cornelia M.
    Swedish Univ Agr Sci.
    Hollman, Peter
    Wageningen Univ, Netherlands.
    Hulshof, Paul J. M.
    Wageningen Univ, Netherlands.
    Glibetic, Maria
    Univ Belgrade, Serbia.
    Porubska, Janka
    VUP Food Res Inst, Slovakia.
    Pepping, Fre
    Wageningen Univ, Netherlands.
    Oshaug, Arne
    Akershus Univ Coll, Norway.
    Training and capacity building in central and eastern Europe through the EuroFIR and CEE networks2009In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 113, no 3, p. 846-850Article in journal (Refereed)
    Abstract [en]

    Capacity building in food and nutrition aims to enhance knowledge and support infrastructural development in this field. International Network of Food Data Systems (INFOODS) was established on the basis of the recommendations of an international group convened under the auspices of the United Nations University (UNU). The European Food Information Resource Network (EuroFIR, Network of Excellence) aims to develop and integrate food composition data through Europe including CEE countries. EuroFIR, joined forces with the United Nations University/UN System Standing Committee on Nutrition, in capacity building. Inventories have been initiated by EuroFIR on food composition data base status and on capacity development needs. The inventories showed that many activities are already ongoing, providing a good potential for developments needed. Substantial differences exist between the countries, including lack of understanding about the concepts and what quality implies. Assessing the quality, frequency of the capacity development activities and the number of staff trained is needed. Several countries lacked adequate information: 6 of 8 had established Food Composition Databases, but none had electronic versions of the Food Composition Databases. Most had national databases, but needs for additional equipment seems considerable. Education, training, workshops, networking and sharing of experiences were cross-cutting themes for most countries. It is concluded that capacity development is a long-term, continuing process, with policies, plans, and activities and should have national priority. Special attention should be given to the capacity development dimensions generated by global and European strategies. Capacity development networks would be important tools in addressing present and future needs in various Countries. The EuroFIR training and exchange program is a valuable tool in achieving this. (C) 2008 Elsevier Ltd. All rights reserved.

  • 7.
    Strålsjö, Lena
    et al.
    Swedish University of Agricultural Sciences.
    Arkbåge, Karin
    Swedish University of Agricultural Sciences.
    Witthöft, Cornelia M.
    Swedish University of Agricultural Sciences.
    Jägerstad, Margaretha
    Swedish University of Agricultural Sciences.
    Evaluation of a radioprotein-binding assay (RPBA) for folate analysis in berries and milk2002In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 79, no 4, p. 525-534Article in journal (Refereed)
    Abstract [en]

    This study aimed to optimise a commercial radioprotein-binding assay (RPBA), routinely used for clinical samples, for folate quantification in foods containing mainly 5-CH3-H(4)folate. The assay was modified using external calibration with 5-CH3-H(4)folate in a lower concentration range diluted in food extraction buffer, rather than the buffer with human serum albumin (HSA) provided by the kit. We evaluated the modified RBPA on some selected food products; milk, whey powder, rose hips, strawberries and European certified reference materials (CRM 421, 485) and the adjustments did not affect the assay negatively. Performance parameters included control of selectivity, absence of matrix effects, recoveries of 94-113%, precision of 1-6 CV% (intra-assay) and 5-9 CV% (inter-assay). Folate concentrations in berries and milk, obtained by the modified RPBA were also compared with other quantification methods such as HPLC and MA. The optimised RPBA was found to be a quick and inexpensive complement to HPLC methods, reliable for folate quantification in foods such as milk and berries that contain mainly 5-CH3-H(4)folate. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 8. Vahteristo, L
    et al.
    Finglas, P M
    Witthöft, Cornelia M.
    Justus Liebig-Universität, Germany.
    Wigertz, K
    Seale, R
    deFroidmontGortz, I
    Third EU MAT intercomparison study on food folate analysis using HPLC procedures1996In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 57, no 1, p. 109-111Article in journal (Refereed)
    Abstract [en]

    Three samples (milk powder, lyophilized pig's liver and wholemeal flour), a 5-methyltetrahydrofolic acid (5-MTHF) calibrant and two deconjugase enzymes (purified hog kidney and human plasma) were circulated to three laboratories taking part in the study. The objectives were to optimize the deconjugation step in these foods and to improve the between-laboratory agreement in HPLC results for folates. The predominant natural folate form in milk powder was 5-MTHF, together with appreciable amounts of folic acid. In pig's liver 5-MTHF was found to represent about one-third of the total folate content found. For these two foods, results from one laboratory of the sum of the folate vitamers agreed favourably with the microbiological data. 5-MTHF was most successfully determined by all three laboratories. There was little or no agreement found for the other folate vitamers detected. Copyright (C) 1996 Elsevier Science Ltd

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