Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products
- PDF / 514,968 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 35 Downloads / 148 Views
Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products Paul W. Johns 1 & Jeffrey H. Baxter 1 & Megan C. Terp 1
Received: 18 January 2017 / Accepted: 5 April 2017 # Springer Science+Business Media New York 2017
Abstract A simple method for the verification of supplemental (6R,S)-5-methyl-5,6,7,8-tetrahydrofolic acid, B5-MTHF,^ in nutritional products is described. Nutritional product samples are prepared for the liquid chromatographic/fluorescence detection (LC/FLD) determination of 5-MTHF by buffer dilution, 10-min centrifugation, and syringe filtration. Method performance has been defined by assessments of 5-MTHF linearity (r2 averaged 0.9999 ± 0.0001, and all relative calibration errors averaged ≤0.6%, for ten consecutive six-point standard curves), intermediate precision (rsd = 1.1%, n = 9, for three products fortified at ∼1.73 μmol/kg = ∼795 μg/kg, tested on each of 3 days), accuracy (spike recovery average = 92.8 ± 1.0%, n = 9, for nutritional products spiked with 5-MTHF at ∼1.73 μmol/kg, or ∼795 μg/kg), and selectivity (absence of interference from reagent blanks, and from four compounds structurally related to 5-MTHF). The 5-MTHF recovery, as % of unheated controls, from a simulated heat treatment (20 min at 120 °C) averaged 99.1 ± 0.6%, n = 4. The limits of 5-MTHF detection (S/N = 3) and quantification (S/N = 10) were experimentally determined to be 10 μg/kg (∼0.020 μmol/kg) and 30 μg/kg (∼0.060 μmol/kg), respectively (1 mg per day) of the synthetic folate vitamer folic acid, the recent commercial availability of the predominant natural folate vitamer 5-MTHF (synthesized and marketed as the calcium salt Metafolin®) has prompted researchers to evaluate its suitability as a biologically favorable alternative to folic acid for the folate
Food Anal. Methods
fortification of various foods (Venn et al. 2002; Pentieva et al. 2004; Indrawati et al. 2004a, 2005; Wang et al. 2011). The selection of 5-MTHF supplemented food matrices evaluated to date includes UHT and pasteurized milk products, wherein bioaccessibilities >70% were found (Verwei et al. 2003), whole meal bread and white bread baked, without and with skim milk powder (without and with added sodium ascorbate) as an encapsulation agent, where recoveries as high as 97% were found (Tomiuk et al. 2012; Chandra-Hioe et al. 2013; Liu et al. 2013), skim milk and soy milk, where ∼75 and ∼60%, respectively, were recovered after 10 h at 50 °C (Liu et al. 2012), and wheat rolls, where stability to baking and storage was achieved (recovery >90%) via 5-MTHF encapsulation with a sodium ascorbate/modified starch combination (Green et al. 2013). These studies were carried out with full recognition of the well-documented vulnerability of 5-MTHF to oxidation, a primary reason for the widespread use of the much more oxidatively stable folic acid (Fig. 1) as the folate fortificant of choice (Nguyen et al. 2003; Strandler et al. 2015). Accordingly, an important advancement associated with the fortified food evaluation studies was the identification of food m
Data Loading...
