We are all interested in food, whether it's for personal consumption or for business. And there's probably nothing else that needs to look so completely appealing for it to achieve the end result you are looking for. As the owner of a restaurant, grocery, bakery, etc. the image you use to promote your product must be tempting. From contrast to colour, presentation is everything.
The same is true of the artist or photographer creating that temptation. There was video a brief while back showing how a popular fast food chain made the photos of their products more appetizing than the real things. It is that that must be achieved whether the medium is photography or illustrations.
While a talented photographer can get the results without tweaking, technology has ensured that even a less than stellar effort can be enhanced. Here then are some links to tutorials for improving your food photos with Photoshop:
Photoshop for Food Photography and the Perfect Pumpkin Pie
The Two Most Important Tools for Food Photographers
Edit Food Photos in Photoshop
Or if beautiful illustrations are your thing there is no shortage of step-by-step instructions for creating everything from soup to nuts with Photoshop. Take a look at these terrific tutorials:
50 Tremendous Photoshop Food Tutorials
35 Best Photoshop Food Tutorials