Determination of folate in some cereals and commercial cereal-grain products consumed in Poland using trienzyme extraction and high-performance liquid chromatography methods

A trienzyme treatment (rat plasma conjugase, alpha-amylase, protease) followed by affinity chromatography (with folate-binding protein from bovine milk) and reversed-phase high-performance liquid chromatography with UV and fluorescence detections was performed for quantification of different folate derivatives in some commercial cereal-grain products and cereals cultivated in Poland. The method described allowed good separation of the main folate vitamins. Of the commercial cereal-grain products analyzed, buckwheat groats (30 mu g/100 g) had the highest content of total folate, followed by rye flour (29 mu g/100 g), barley groats (21 mu g/100 g) and wheat flours (19-20 mu g/100 g). Two of the ready-to eat breakfast products were found to be fortified with folic acid with the level slightly exceeding the label declaration. The total folate content of whole-grain wheat flours was more than half as much as in white flours (33-40 mu g/100 g), and the highest folate content was found in rye whole grains (123-135 mu g/100 g). 5-Formyltetrahydrofolate was the predominating folate form in the cereal products analyzed, above all in rye flour.