The composition of food photography is how the object is positioned in the photo. But when you take a food photo, you got to think about the aspects of composition. Your photo needs good balance, symmetry, depth of field, texture, and/or background. The photo doesn't need all of these ideas, but it is a good idea to include a majority of them.
Step 1: Balance
It is important to keep the photo balanced when taking a photo. You don't want the photo to have too much stuff on one side. If you have something on one side of the photo, try to balance it out with something similar to it on the other side. If the photo is too heavy on one side, the viewer eyes will be dragged to it and won't get a good look at what else is in the photo.
Step 2: Symmetry
Often times in food photography you want a symmetrical photo. This kinda goes with balance, except more specific. Symmetry has to do with the object being centered and having the same items on both sides. You could say that symmetry is a subcategory of balance. When there is symmetry in a photo it looks more appealing to the eye. If you want the photo to be symmetrical, the background is important. Which is what I am covering next.
Step 3: Background
The background has a lot to do with the positioning of the food item. You want the background to be simple or have something to do with the food item. You could position an orange where it lines up exactly with the sun, or you could take a picture of some dough on a kitchen counter with a bowl and a whisk. Having things in your background will give the viewer a better understanding of what the meaning of the photo is. In the end, you should have your background be simple.
Step 4: Texture
Texture is a composition style that the viewer doesn't realize as soon as the other styles. The viewer will definitely feel the texture just form looking at the photo (if it is done correctly). If you do it well, it will give viewer a sense of taste of what the food is. For this you need to take a close up photo, if need be you can turn up the clarity in light-room when editing. For this you will also need a good background that doesn't distract the viewer from the object.
Step 5: Depth of Field
Once again, background is an important factor in order for this to be executed well. If you focus on the object and the background is blurred, it will draw more attention to main focus of the photo. The best way to use depth of field is with simple object, otherwise the viewer won't know what is in the background. For example, having the stem of a banana in the foreground and the rest of the banana in the background. In that case, the viewer knows that the rest of a banana is in the background.