Quantitation of N2-[1-(1-carboxy)ethyl]folic acid, a nonenzymatic glycation product of folic acid, in fortified foods and model cookies by a stable isotope dilution assay

Michael Rychlik, Anja Mayr

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

A stable isotope dilution assay (SIDA) for the quantitation of N 2-[1-(carboxy)ethyl]folic acid (CEF) has been developed by using [2H4]CEF as the internal standard. After sample cleanup by anion exchange chromatography, the three-dimensional specifity of liquid chromatography-tandem mass spectrometry enabled unequivocal determination of the nonenzymatic glycation product of folic acid (FA). When CEF was added to cornstarch, the detection limit for CEF was found to be 0.4 μg/100 g, and a recovery of 98.5% was determined. In analyses of cookies, the intra-assay coefficient of variation was 8.0% (n = 5). Application of the SIDA to commercial cookies produced from wheat flour fortified with FA revealed CEF contents of up to 7.1 μg/100 g, which accounted for ∼10-20% of the cookies' FA content. In baby foods, multivitamin juices, and multivitamin sweets, however, CEF was not detectable. Further studies on CEF formation during baking of cookies made from fortified flour and different carbohydrates revealed that fructose was most effective in generating CEF followed by glucose, lactose, and sucrose with 12.5, 3.9,2.5, and 2.5 μg/100 g of dry mass, respectively. During baking, ∼50% of FA was retained for both monosaccharides fructose and glucose, and 77% as well as 85% of its initial content was retained for the disaccharides lactose and sucrose, respectively. Of the degraded amount of FA, CEF comprised 28% for fructose as well as 18, 12, and 8% for sucrose, lactose, and glucose, respectively. Therefore, CEF can be considered an important degradation product of FA in baked foods made from fructose. To retain a maximum amount of FA, products should rather be baked with sucrose than with reducing carbohydrates.

Original languageEnglish
Pages (from-to)5116-5124
Number of pages9
JournalJournal of agricultural and food chemistry
Volume53
Issue number13
DOIs
StatePublished - 29 Jun 2005

Keywords

  • Carboxyethyl folic acid
  • Folic acid
  • Fortified foods
  • Maillard reaction
  • Nonenzymatic glycation
  • Stable isotope dilution assay

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