Vu Chau Hai Thai, Won Keehoon
Department of Chemical and Biochemical Engineering, Dongguk University-Seoul , 30 Pildong-ro 1-gil, Jung-gu, Seoul 100-715, Republic of Korea.
J Agric Food Chem. 2014 Jul 23;62(29):7263-7. doi: 10.1021/jf5014764. Epub 2014 Jul 10.
Visual oxygen indicators can give information on the quality and safety of packaged food in an economic and simple manner by changing color based on the amount of oxygen in the packaging, which is related to food spoilage. In particular, ultraviolet (UV)-activated oxygen indicators have the advantages of in-pack activation and irreversibility; however, these dye-based oxygen indicator films suffer from dye leaching upon contact with water. In this work, we introduce carrageenans, which are natural sulfated polysaccharides, to develop UV-activated colorimetric oxygen indicator films that are resistant to dye leakage. Carrageenan-based indicator films were fabricated using redox dyes [methylene blue (MB), azure A, and thionine], a sacrificial electron donor (glycerol), an UV-absorbing photocatalyst (TiO2), and an encapsulation polymer (carrageenan). They showed even lower dye leakage in water than conventional oxygen indicator films, owing to the electrostatic interaction of anionic carrageenan with cationic dyes. The MB/TiO2/glycerol/carrageenan oxygen indicator film was successfully bleached upon UV irradiation, and it regained color very rapidly in the presence of oxygen compared to the other waterproof oxygen indicator films.
视觉氧气指示剂可以通过根据包装中的氧气量改变颜色，以经济简便的方式提供有关包装食品质量和安全性的信息，而包装中的氧气量与食品变质有关。特别是，紫外线（UV）激活的氧气指示剂具有包装内激活和不可逆的优点；然而，这些基于染料的氧气指示膜在与水接触时会出现染料渗漏问题。在这项工作中，我们引入了角叉菜胶，一种天然的硫酸化多糖，来开发抗染料渗漏的紫外线激活比色氧气指示膜。基于角叉菜胶的指示膜是使用氧化还原染料[亚甲基蓝（MB）、天青A和硫堇]、牺牲电子供体（甘油）、紫外线吸收光催化剂（TiO2）和封装聚合物（角叉菜胶）制成的。由于阴离子角叉菜胶与阳离子染料的静电相互作用，它们在水中的染料渗漏甚至比传统氧气指示膜更低。MB/TiO2/甘油/角叉菜胶氧气指示膜在紫外线照射下成功褪色，并且与其他防水氧气指示膜相比，在有氧气存在的情况下能非常迅速地恢复颜色。
