"Food additive" means any synthetic compound or natural substance put into food to improve its quality, colour, fragrance or taste, or for the sake of preservation or processing.
The title compound has a reversible photochromic property. A possible photochromic mechanism was proposed based on the ESR spectra of colour-changed samples.
该化合物均具有可逆的光致变色特性，基于变色后样品的电子自旋共振(esr)谱提出一个可能变色机理。
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Pigment: Any intensely coloured compound used to colour other materials.