Ohrvik Veronica, Witthöft Cornelia
Dept. of Food Science, Swedish University of Agricultural Sciences, Box 7051, 75007 Uppsala, Sweden.
Eur J Nutr. 2008 Mar;47(2):92-8. doi: 10.1007/s00394-008-0701-3. Epub 2008 Mar 4.
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. 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.
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).
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.
5-CH(3)-H(4)folate was the dominant natural folate form in the juices with contents ranging from 16-30 microg/100 g. Shelf life losses of folic acid fortificant were 1-4%. During one week simulated household consumption 5-CH(3)-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.
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.
据估计，瑞典育龄妇女的平均叶酸摄入量低于推荐每日摄入量（RDI）的55%（Becker和Pearson，《瑞典1997 - 1998年食品消费与营养摄入》。国家食品管理局，乌普萨拉，第34、44、121页，2002年）。由于良好的叶酸状态可降低神经管缺陷的风险，一些欧洲国家正在讨论强制添加叶酸强化剂。然而，这可能会导致某些人群无意中摄入大量叶酸，因此有针对性的叶酸强化可能是一种替代方案。
（1）测定瑞典销售的三种流行品牌橙汁中的天然叶酸含量；（2）测定叶酸/铁强化橙汁在保质期内天然叶酸和叶酸强化剂的稳定性；（3）测定四种果汁在模拟家庭消费一周期间的叶酸稳定性；（4）使用TNO胃肠道模型（TIM）测定一个品牌橙汁中天然叶酸的体外生物可及性。
使用反相高效液相色谱 - 荧光法（RP - HPLC - FL）测定果汁中的天然叶酸含量。使用液相色谱 - 质谱联用仪（LCMS）测定叶酸含量并确认RP - HPLC - FL值。在未开封的叶酸/铁强化果汁瓶中测定保质期内的稳定性，并在家庭消费条件下，每天重新开封的情况下，对四种流行果汁进行一周的稳定性测定。在橙汁中进行体外叶酸生物可及性实验时，使用TNO TIM模型。
5 - 甲基 - 四氢叶酸（5 - CH(3)-H(4)folate）是果汁中主要的天然叶酸形式，含量范围为16 - 30微克/100克。叶酸强化剂在保质期内的损失为1 - 4%。在模拟家庭消费一周期间，5 - CH(3)-H(4)folate含量下降高达7%（无统计学意义）。橙汁中天然叶酸的生物可及性几乎为100%。试验开始后60 - 120分钟内，大部分叶酸在空肠中释放以供吸收。
就储存和模拟消化过程中的含量和稳定性而言，橙汁可被视为天然叶酸的良好来源。此外，叶酸/铁强化橙汁中添加的叶酸强化剂在保质期内是稳定的。
