powder soluble in water
Yellow coloring E102 powder soluble in water - 25 g. - Azo Free
In sugar we mainly use food coloring already diluted in water, therefore completely water soluble, their concentration must be strong enough, 20 g of powder of 100 g of boiling water.
The addition in cooking can be done at any temperature, but the one which I believe is the best, is at the beggining when the sugar crystals are not yet dissolved in the water, in this way the absorption is greater. Davide Malizia