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.
They are also getting strict about having large bottles of liquids because of the fear of liquid bombs.