I thought that it was something to help out if someone gets trapped in the pantry, but based on the scene, it seems like that's not the case.
What is this object?
It's a commercial walk-in refrigerator door handle, known as a 'push-strike'
Basically it just pushes through the door onto the regular latch on the outside so you can get out... unless in this case someone has locked it from the outside. You can bump it with your butt if your hands are full.
Late edit: I found a shot of both sides of the door from the movie...