Matella Norman J, Braddock Robert J, Gregory Jesse F, Goodrich Renée M
Food Science and Human Nutrition Department, University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA.
J Agric Food Chem. 2005 Mar 23;53(6):2268-74. doi: 10.1021/jf048285c.
The 5-methyltetrahydrofolate (5mTHF) polyglutamates in citrus products were analyzed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Folate species were purified from citrus products and concentrated from 2- to 100-fold using combined folate-affinity chromatography and C18 extraction. Seven polyglutamyl 5mTHFs were found in most not-from-concentrate (NFC) orange juices (OJ) in total amounts of approximately 1 nmol/mL, with varying distributions of individual polyglutamates. Folate amounts and distributions were also measured in orange fractions, single-strength OJ from concentrate, NFC grapefruit juice, and citrus peel molasses. Models containing ascorbic acid had folate thermal degradation rates one-seventh that of models without ascorbic acid. Pasteurization studies demonstrated that folate loss was <2% for commercial OJ pasteurization conditions (i.e., 93 degrees C for 5 s, 88 degrees C for 15 s, and 82 degrees C for 30 s). Both methods were precise, reproducible, and potentially faster than traditional analytical procedures requiring enzymatic deconjugation and microbial assays.
采用毛细管电泳（CE）和高效液相色谱（HPLC）对柑橘类产品中的5-甲基四氢叶酸（5mTHF）多聚谷氨酸进行了分析。从柑橘类产品中纯化叶酸种类，并使用叶酸亲和色谱和C18萃取法将其浓缩2至100倍。在大多数非浓缩还原（NFC）橙汁（OJ）中发现了7种多聚谷氨酰基5mTHF，总量约为1 nmol/mL，各多聚谷氨酸的分布有所不同。还对橙子各部分、浓缩汁单倍强度OJ、NFC葡萄柚汁和柑橘皮糖浆中的叶酸含量和分布进行了测定。含抗坏血酸的模型中叶酸的热降解率是不含抗坏血酸模型的七分之一。巴氏杀菌研究表明，在商业OJ巴氏杀菌条件下（即93℃ 5秒、88℃ 15秒和82℃ 30秒），叶酸损失<2%。这两种方法都精确、可重复，并且可能比需要酶解偶联和微生物检测的传统分析方法更快。
