〓CCTV《每周质量报告》说过调味料的苏丹红，并教了用食用油自己检测调味料有无苏丹红的方法，是怎么说的

That harmful substance is organic, attributing to its miscibility with other organic solvents, such as oil.

Therefore, the Sudan-1 does not dissolve in water, but in oil. As for how to identify it, I think you must have known according to the above notion--It may be Sudan-1 when you see the colour dissolve in the oil!

However, I am afraid that some other colorful additives also dissolves in oil. So you may sometimes mistake some non-harmful additives as Sudan-1.

That's all.