Most folate was released for absorption in jejunum between 60–120 min after trial start. Bioaccessibility of natural folate in orange juice was almost 100%. During one week simulated household consumption 5-CH 3-H 4folate content decreased by up to 7% (n.s).
Shelf life losses of folic acid fortificant were 1–4%. Resultsĥ-CH 3-H 4folate was the dominant natural folate form in the juices with contents ranging from 16–30 µg/100 g. For an in vitro folate bioaccessibility experiment in orange juice the TNO TIM Model 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. To determine folic acid content and confirm RP-HPLC-FL values LCMS was used. Natural folate content in juices was determined using RP-HPLC-FL. 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). 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. Because a good folate status reduces the risk of neural tube defects, mandatory folic acid fortification is discussed in some European countries. National Food Administration, Uppsala, pp 34, 44, 121, 2002). 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 näringsintag i Sverige.