The studio i intern at does alot of food photography, if anyone here is familiar with Burgerville, we do all the photography for them. We shoot it on a Hasselblad H2D-22. The burgers are shot with a 50mm, everything else on a 120mm. The only reason we shot it on the Hassy is because we have one, and we can give the client absolute IQ.
Can you do exactly that? of course not. But you can get close, and you don't need no stinkin' tilt-shift lens.
Generally, if you look in publications with photos of some sort of food in them, you'll see that they're lit from the rear most of the time with the soft shadows going towards the camera.
You'll need at least two lights, with some sort of diffusion material. for example, you can have 2 medium-to-large softboxes, one in the rear, and one in the front dialed down a little, which will give you a pretty generic result like what's below. You shouldn't need more than 4. Speedlights are a great, cheap way to get prefect results.
Any DSLR will work. You can totally get a D3000, or a used D40/60 if you want, no need to spend more than you have to. in the studio, the only thing a D90 or 50D will give you are a coupla more megapixels, which when you're talking about 10-12, you won't see that in print. Not to mention you'll be shooting at ISO 100 anyway, so again, it's a moot point, really. Live view
might be important, but at those short distances, it should be really easy to see where your focus is anyway.
You don't
need a tilt-shift lens. anything 50mm (on 35mm format) or longer will do fine. just stop it down. Even the kit lenses should be fine honestly, because optically they're pretty good stopped down, it's just their construction is cheap, and they might not be the best wide open, and you're not going to shoot wide open hardly at all because there won't be enough DOF.
You probably know this, and i'm sure you can do alot towards it, but stylists...are worth their weight in gold. I learned that the hard way when i was working on shoe catalogs last year.
Just look at the Pillsbury flickr page, food photography is generally very formulaic, and often the hardest part is timing hot foods with the stylist.
http://www.flickr.com/photos/pillsburyrecipes/
and some examples from their page: