lipo·chrin

lipo that's easy-- a root word for a fat.
chrin.. makes me think of chrome. a root word for color (specifically: yellows, reds and greens.. the metal chrome gets it name from the various oxides of chrome (chrome yellow, chrome red, and chrome green)
(fat(that is) colored (yellow).. works for me..

maybe is was used to dye bacteria or other organic matter to make it easier to see under a microscope? ether is poisonous.. it can't be to make a food dye. it doesn't seem like it would ever be easy enough to collect enough to use it as a textile dye. Yellow is a pretty easy color to extract from many plant materials.

is there any more info in the dictionary you are reading?

i don't see it the single volume Oxford universal (but the OUD does confirm lipo is from the greek for fat. )