Absolutely. I used to pack milk powder in plastic bags (less bulky without the container) when I was traveling with my young children. I had been made to open my luggage on many occasions when clearing custom. They must have a way to inform the officer at the exit. Subsequently, I decided to hand carry the milk powder to avoid these unnecessary checks.What some people don't realise is that luggage are scanned before being put on conveyor belt.
A friend packed some bottles of unique beer bottles as keepsakes but was pulled "at random" by customs just prior to exit.