Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS

Abstract

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 μg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).

Keywords: 10-Formylfolic acid (PubChem CID: 135405023); 5,10-Methenyltetrahydrofolate (PubChem CID: 135398657); 5-Formyltetrahydrofolate (PubChem CID: 135402009); 5-Methyltetrahydrofolate (PubChem CID: 135415868); Deconjugase; Folic acid (PubChem CID: 135398658); Homogenization; Inter-laboratory study; Plant enzyme; Tetrahydrofolate (PubChem CID: 135444742); Tetrahydrofolates.