Orange juice is a good folate source in respect to folate content and stability during storage and simulated digestion

Background Estimated average folate intake in Sweden is less than 55% of the recommended daily intake (RDI) for women of childbearing age (Becker and Pearson in Riksmaten 1997-1998 Kostvanor och naringsintag i Sverige. National Food Administration, Uppsala, pp 34, 44, 121, 2002). Because a good folate status reduces the risk of neural tube defects, mandatory folic acid fortification is discussed in some European countries. This however, could lead to exposure to unintentionally high amounts of folic acid for some population groups, therefore targeted folic acid fortification could be an alternative. Aims To (1) determine natural folate content in three popular brands of orange juice sold in Sweden, (2) determine stability of natural folate and folic acid fortificant during shelf life in a folic acid/iron fortified orange juice, (3) determine folate stability in four juices during simulated household consumption for one week and (4) determine the in vitro bioaccessibility of natural folate in one brand of orange juice using the TNO gastroIntestinal Model (TIM). Methods Natural folate content in juices was determined using RP-HPLC-FL. To determine folic acid content and confirm RP-HPLC-FL values LCMS was used. Stability during shelf life was determined in unopened bottles of a folic acid/iron fortified juice and for one week in four popular juices under household consumption conditions with reopening of bottles daily. For an in vitro folate bioaccessibility experiment in orange juice the TNO TIM Model was used. Results 5-CH3-H(4)folate was the dominant natural folate form in the juices with contents ranging from 16-30 mu g/100 g. Shelf life losses of folic acid fortificant were 1-4%. During one week simulated household consumption 5-CH3-H(4)folate content decreased by up to 7% (n.s). Bioaccessibility of natural folate in orange juice was almost 100%. Most folate was released for absorption in jejunum between 60-120 min after trial start. Conclusion Orange juice may be considered a good source of natural folate in respect to content and stability during storage and simulated digestion. Moreover, added folic acid fortificant in a folic acid/iron fortified orange juice was stable during shelf life.