Recently my sis.-in law told me that her grandson ( Gerald) has adverse reaction after eating food that contains colouring additives....(Dr told them that the child becomes hyperactive bcos of that. Thus the family avoid giving him such food and it works.
His favourite Asian ondeh ondeh whereby some green colouring is added to make it darker green as pandan juice alone cant give it the desired colour.
Thus one can substitute with natural food colouring.
Eg. omit the green colouring additive & just use more pandan juice instead of more water.
Or buy the orange type of sweet potato and add pandan juice & U get a yellow color for the ondeh ondeh. Thats what I make for my family also for Gerald
As for Tandoori chicken instead of adding red food colouring to make it look appetising , replace it with a pce. of purplish red beetroot (chopped into small pces.)
and mix with the chicken ---- U get the colour.
Your agar agar powder comes in different colours . Orange juice can substitute your orange color , beet root for red or add fruits to make your white agar looks attractive as in Konnyaku jelly.
Visit this site to read more on food colouring effects.