Kika de la Garza Subtropical Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Weslaco, Texas 78596, USA.
J Agric Food Chem. 2010 Apr 28;58(8):4901-6. doi: 10.1021/jf100146m.
Ionizing radiation of fruits and vegetables, in the form of gamma rays or electron beams, is effective in overcoming quarantine barriers in trade and prolonging shelf life, but a void of information persists on ionizing radiation effects of vitamin profiles in individual foods. Baby-leaf spinach from commercial cultivars, flat-leafed 'Lazio' and crinkled-leaf 'Samish', was grown, harvested, and surface sanitized according to industry practices. Baby-leaf spinach of each cultivar was packaged under air or N(2) atmosphere, representing industry practices, then exposed to cesium-137 gamma-radiation at 0.0, 0.5, 1.0, 1.5, or 2.0 kGy. Following irradiation, leaf tissues were assayed for vitamin (C, E, K, B(9)) and carotenoid (lutein/zeaxanthin, neoxanthin, violoxanthin, and beta-carotene) concentrations. Atmospheres by irradiation had little consistent effect, but N(2) versus air was associated with elevated dihydroascorbic acid levels. Four phytonutrients (vitamins B(9), E, and K and neoxanthin) exhibited little or no change in concentration with increasing doses of irradiation. However, total ascorbic acid (vitamin C), free ascorbic acid, lutein/zeaxanthin, violaxanthin, and beta-carotene all were significantly reduced at 2.0 kGy and, depending on cultivar, were affected at lesser doses of 0.5 and 1.5 kGy. Dihydroascorbic acid, the most affected compound and an indicator of stress, likely due to irradiation-generated oxidative radicals, increased with increasing irradiation doses >0.5 kGy.
果蔬辐照以γ射线或电子束形式进行，可有效克服贸易中的检疫障碍并延长货架期，但关于辐照对个体食物中维生素谱的影响，信息仍然匮乏。按照行业惯例，种植、收获和表面消毒商业品种婴儿菠菜（平叶 'Lazio' 和皱叶 'Samish'）。将每个品种的婴儿菠菜分别用空气或 N(2) 包装，代表行业惯例，然后用铯-137 γ射线照射 0.0、0.5、1.0、1.5 或 2.0 kGy。辐照后，测定叶片组织中的维生素（C、E、K、B(9)) 和类胡萝卜素（叶黄素/玉米黄质、新黄质、紫黄质和β-胡萝卜素）浓度。辐照对气氛的影响不大，但 N(2) 与空气相比与二氢抗坏血酸水平升高有关。四种植物营养素（维生素 B(9)、E 和 K 以及新黄质）的浓度随辐照剂量的增加而变化很小或没有变化。然而，总抗坏血酸（维生素 C）、游离抗坏血酸、叶黄素/玉米黄质、紫黄质和β-胡萝卜素在 2.0 kGy 时均显著降低，且取决于品种，在 0.5 和 1.5 kGy 时受影响较小。二氢抗坏血酸是受影响最大的化合物，也是应激的指示剂，可能是由于辐照产生的氧化自由基所致，随着辐照剂量>0.5 kGy 而增加。
