The objective of the research study was to assess the content of folates in commercial milk and fresh kefirs and yoghurts as well as in kefirs and yoghurts that were stored at a refrigeration temperature for max 34 days. Kefirs and yoghurts were produced using a thermostatic method. In the samples tested, only a methyl form of folate (5CH3FH4) was identified. In the raw bulk milk, the content of 5CH3FH4 was ca. 4.0 µg/100 g. The process of milk pasteurization do not cause decreasing of the folate content. In the kefir samples, no changes were reported in the amount of 5CH3FH4 compared to the raw bulk milk; however, a significant decrease (p ≤ 0.05) was found in the content of folate in the yoghurts. The storage time had a different effect on the content of 5CH3FH4 in the kefirs. In one series of the kefirs, no significant decrease occurred in the content of 5CH3FH4; however, in the second series, a significant increase was found in the content of folates after a 19 day storage, then, it was followed by a significant decrease after a storage period of 21 days. In the two series of yoghurts, a content of folates was found to decrease during refrigeration storage.
folates, kefir, yoghurt, HPLC, storage