This is an interesting idea for a submission but there are a couple of things that let it down. First of all there's a clear lack of detail, especially in the rings of the onion. I'm not sure if this is your camera or your post processing. The second thing is that although your lighting is good there are strong green shadows. This gives me the impression that either your white balancing is off or your post processing has been too harsh.
This is a shot I think would be worth re-shooting at some point.
the shadows have a really green cast. You can get rid of the line in the beckground (caused by angle between table and wall) by puting your subject on a curved white piece of posterboard or somthing similar.