Capillary Electrophoresis and High-Performance Liquid Chromatography Determination of Polyglutamyl 5-Methyltetrahydrofolate Forms in Citrus Products

Abstract

The 5-methyltetrahydrofolate (5mTHF) polyglutamates in citrus products were analyzed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Folate species were purified from citrus products and concentrated from 2- to 100-fold using combined folate-affinity chromatography and C18 extraction. Seven polyglutamyl 5mTHFs were found in most not-from-concentrate (NFC) orange juices (OJ) in total amounts of approximately 1 nmol/mL, with varying distributions of individual polyglutamates. Folate amounts and distributions were also measured in orange fractions, single-strength OJ from concentrate, NFC grapefruit juice, and citrus peel molasses. Models containing ascorbic acid had folate thermal degradation rates one-seventh that of models without ascorbic acid. Pasteurization studies demonstrated that folate loss was <2% for commercial OJ pasteurization conditions (i.e., 93 degrees C for 5 s, 88 degrees C for 15 s, and 82 degrees C for 30 s). Both methods were precise, reproducible, and potentially faster than traditional analytical procedures requiring enzymatic deconjugation and microbial assays.

Recent developments in capillary electrophoresis and capillary electrochromatography of peptides

“…The other applications of CE techniques to peptide analysis in complex matrices include determination of polyglutamyl 5-methyltetrahydrofolate forms in citrus products [259], analysis of para-k-casein and related peptides as indicators of milk proteolysis [260], and analysis of polypeptide and protein allergens in water and waterbuffer extracts from tree (Betula verrucosa) and grass (Dactylis glomerata) pollens and airborne dust samples [261,262].…”

In silico prediction of gene expression patterns in Citrus flavedo

“…Several genes have been sequenced, their copy number and expression have been studied and their products analyzed regarding function in various tissues. Particular interest has been paid to fruit genes and gene products involved in the flavonoids, vitamins, and organic acid biosynthesis, among others (Moriguchi et al, 1999;Matella et al, 2005;Shimada et al, 2006). However, to our knowledge, the only genomewide study involving citrus ESTs that contains flavedo sequences already published included 5,604 ESTs from Citrus clementina fruits (Forment et al, 2005).…”

Recent advances in the application of capillary electromigration methods for food analysis

“…Orange juice is a good source of folate, which is mainly in the form of polyglutamyl 5-methyl tetrahydrofolates. A CZE-DAD method was developed for the analysis of 5-methyl tetrahydrofolates forms in orange juice [77].…”