Ultraviolet-Induced Oxidation of Ascorbic Acid in a Model Juice System: Identification of Degradation Products
Ultraviolet-Induced Oxidation of Ascorbic Acid in a Model Juice System: Identification of Degradation Products
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DOI：
10.1021/jf201000x
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发表时间：
2011-08-10
影响因子：
6.1
通讯作者：
LaBorde, Luke F.
中科院分区：
文献类型：
--
作者：
Tikekar, Rohan V.;Anantheswaran, Ramaswamy C.;LaBorde, Luke F.
本文报道了抗坏血酸（AA）经紫外线（UV-C，254 nm）处理后的降解产物。在0.5%苹果酸模型果汁系统（pH 3.3）中进行的高效液相色谱-质谱（HPLC-MS）分析表明，AA的降解比未处理的对照组增加，同时脱氢抗坏血酸（DHA）和2，3-二酮古洛糖酸（DKGA）水平增加。在磷酸盐缓冲液（pH 7.0）中进行的电子自旋共振（ESR）光谱研究，以增加检测灵敏度，表明抗坏血酸自由基（AA（中心点））的形成与AA降解同时发生。与先前的研究一致，其中UV处理显示出加速暗储存降解，AA（中心点）自由基在初始UV处理后持续形成长达200分钟。从这项研究的结果表明，紫外光诱导降解的机制是相同的金属催化氧化果汁中的AA的一般机制。
Degradation products of ultraviolet (UV-C, 254 nm) treated ascorbic acid (AA) are reported. Analysis by high-performance liquid chromatography mass spectroscopy (HPLC-MS) conducted in a 0.5% malic acid model juice system (pH 3.3) demonstrated increased degradation of AA above untreated controls with concomitant increases in dehydroascorbic acid (DHA) and 2,3-diketogulonic acid (DKGA) levels. Electron spin resonance (ESR) spectroscopy studies, conducted in phosphate buffer (pH 7.0) to increase detection sensitivity, demonstrated that ascorbyl radical (AA(center dot)) formation occurs simultaneously with AA degradation. Consistent with a previous study in which UV treatments were shown to accelerate dark storage degradation, AA(center dot) radicals continued to form for up to 200 min after an initial UV treatment. Results from this study suggest that the mechanism for UV-induced degradation is the same as the general mechanism for metal-catalyzed oxidation of AA in juice.