Is this food?

Whenever I see my human go into the food room (I think I've heard him say 'kit-chin'), I know that he may well be passing me with something to eat in a while.

Normally, he'll walk past and already have food to his mouth. This confirms that I need to get up from my nap, stretch, then walk over and stare at him.

Sometimes I'll jump up on the table at which my human is sat, and stare at him even more.

Something confuzzles me, though. Sometimes my human will have what looks like food, but it doesn't smell like food... or it just smells weird.
I've seen him with this strange yellow thing in his hand. It has some kind of skin on, which he peels. I'll wander over and meow to show that I'd like to sniff it, but when I sniff it, it doesn't smell tasty, so I walk off.
I've also seen him with a round, green thing with a stalk at the top. This also doesn't smell that tasty.

What are these things? Are they food? If they are, then why don't they smell of it?
Very strange...