Okay, don't know for sure what the setting is like, what the lighting is like, how much privacy and ability to re-arrange the food you'll have and how much experience you have. But total ignorance on a situation has never stopped me from commenting before.
1. I second Derrel's recommendation about continuous lighting. You don't need to be tethered, you don't have to come back and reshoot. You can see where the shadows are, where the reflections are.
2. Learn how to adjust your white balance. NO, using "Auto white balance" won't cut it (that will just average the highlights so you end up with shots that have no pop to them.
3. Be absolutely, explicitly, totally, crystal clear about what the client expects. Food pictures of food as it's set up in the grocery store? Or in a studio-like setting (meaning you can take the celery and put it in a white backdrop or on a small seamless white paper setup)? Can you re-arrange it or do you have to shoot it as is? It's a totally different situation...shooting food in a grocery store as it's arranged (and you look for good angles) vs. food that is set aside, rearranged or prepared so it looks great with a backdrop that isn't distracting vs. food in isolation (one head of lettuce, one apple, one pear, one banana, etc.) with the objective to create exactly the same look and finish and setting for each picture.
4. Visit the setting ahead of time. I expect you'll find:
--lots of chrome and glass/plexiglass that will create hot spots and distracting reflections
--food that is generally okay but the celery or lettuce or beets have a little dirt on them or there's a bruise on most of the apples or fingerprints on the OJ bottle....none of which stand out to the customer's eye but your camera will capture perfectly.
--very uneven lighting...areas with some daylight, areas with bright lighting, others where it's dark or the light is burned out. And if you're supposed to shoot 500 products and make the lighting and setting and appearance identical (for product references or fliers) then that's a major problem.
I think your best best (after having done recon at the store) is to find someplace there where you can set up a mini-studio (i.e.: clean white surface, white walls, consistent light) and have people bring you products (which you shoot). That will generate a consistent look to all of the shoots, speed up the process, and probably make the client happy.