Just some observations:
1) too little dof for some shots. Not to single out one particular picture, but having only the tip of the strawberry slice in focus is not "artistic" at all. DOF control is very important, and which is sorely abused by many users of fast lenses.
You are attempting to capture the essence of the entire food being presented, so (say in another picture), why is the focus on just one pea instead then? Why is that pea / strawberry tip / [insert point of focus] so important that you have your entire focus on? Ask yourself these questions when reviewing your pics.
2) Harsh lighting. If using strobes, use reflectors/diffusers to even out the light. Top-down lighting *can* work for food shots. Afterall, when we view most of our food, they are lighted from the top anyway. Side/frontal lighting can and may cause the food to look too flat and not enough volume (very important for food that you want to showcase shape/depth).
3) Distracting backgrounds
Ambient lighting and nice backgrounds can work, but they should not interfere with the presentation of the food. In some cases, the background overpowers the food, and I don't see the food at all.
4) White balance and exposure
Food often looks more pleasant when slightly overexposed (but not to the point of getting blown out, as correctly mentioned by one poster (ProImage) earlier). If your exposure is too dark, the food (or any other subject for that matter) will look very muddy, and is very difficult to recover in photoshop.
White balance also very important - blue cast makes food look very unappetizing. Warm tungsten-y cast (think cafe/restaurant setting) works well in some cases e.g. pastries (brown coloured food). If photographing veges, neutral WB is recommended to bring out the greens - you don't want a muddy, brownish green for ur vegs if you use tungsten light - very unappetizing
