Wiktionary
fast yellow ab
alt. (context chemistry English) a yellow azo dye formerly used as a food colouring n. (context chemistry English) a yellow azo dye formerly used as a food colouring
Wikipedia
Fast Yellow AB
Fast Yellow AB is an azo dye. It used to be used as a food dye, designated in Europe by the E number E105. It is now delisted in both Europe and USA and is forbidden if used in foods and drinks, as toxicological data has shown it is harmful. E105 has been implicated in non-atopic asthma.