I understand your message here, I myself have used flour to create a perception of drugs, but the colours are taking away the realism here, which may be intentional but I would change the colour balance to reduce the yellows and make the "powder" more white. you'll get a better effect that way.

Thank you for your comment. Yes, it was intentional because I didn't want it to look very realistic. After all the kind of flour that I used is a little yellow. And, yes - you are right, changing the colour balance would certainly make it more white.

I think the glare is what is throwing it off the most.