The simplest objects in food photography should be white, but the most complex objects can end up being white too. A white plate can appear blue when placed next to a cool window, a white napkin can look yellow when lit by warm indoor bulbs, and a very light table surface can become an unnatural shade of gray when edited. It then doesn’t look as much like the food because you’ve lost the sense of color realism in the photo.
Often, this problem is the color temperature or white balance of the camera (or smartphone) itself. If you use a white plate in a setup that contains mostly non-white colors, the camera is going to be confused when trying to determine a good color temperature or white balance setting. A cool window, a wooden serving board, a wall with color, a patterned napkin, or a warm kitchen light can all throw off the color accuracy of the plate and food. The white plate might be white, but if the light source around it is warm, the camera might be forced to render the whole image too yellow. On the flip side, if your setup is in shadow, that same white plate can look too cool and blue.
A quick test you can try to avoid the problem before the shoot is to set up the image with no props (just the food and a small portion of the plate). Take a test photo without any extra props and look for the white areas of the photo. Do they still look very white, or are they showing a strong color cast? This will give you the best idea of what’s happening, and if a white area is really off-color, you’re going to have trouble with the final result, regardless of how many additional props you put in the shot: silverware, a splash of sauce, garnish, table setting, background surface, etc.
It is hard to get natural, white colors in an image when you have a mix of light sources. If you’re shooting with window light but also have your kitchen lighting on, your image will pick up both a cool cast on the shadows (the window light) and a warm cast on the highlights (the bulbs). A white plate can look blue on the shadowed side and yellow on the highlighted side. The best option for good food photos is to try and use only one light source. Turn off your kitchen lighting, shoot closer to the window, or filter some of the daylight out if the window is blowing the highlights out and leaving you with too little shadow detail on the plate.
Your image will change too if your props are throwing color off the surfaces. A brightly colored napkin can pick up color from the napkin onto a white plate. A wooden serving board can give the food a warmer tone. A dark background will throw off the exposure, which will cause a problem in that the camera will be trying to lighten the photo too much, and leave you with the plate overexposed, without much detail along the edge of the plate. It is much easier to evaluate the color of the scene while you’re setting up your props with neutral-colored plates, a white or pale linen, and a non-saturated background surface.
It is also easy to over-edit the plate or napkin when fixing the color balance of your food. Slowly adjust the white balance (color temperature and tint) of your photo while checking your results. Your cream, rice, breads and buns, yogurt, pastries and frosting, pasta, or white pasta sauce are not supposed to look blue or very yellow (unless you took the photo that way). It is also easy to over-saturate your image. While it is great if you give a small boost to the saturation to help bring out the color of your herbs and vegetables and fruit, your plate will look artificial if your tomatoes, sauce, or bread crusts look too saturated while they sit next to a white plate.
A white plate will not distract your viewer if your plate, napkin, and food all feel as if they’re sitting together in natural light. The white of the plate does not have to be perfectly white. It should just not be glaringly off color to the viewer in an unnatural way. The best way to check if your photo is natural is by looking at the before and after of your edits. Make sure your corrections have resulted in a good photo that doesn’t look too much like you edited, but rather looks more like a realistic representation of the food. Good white balance will keep the attention focused on your food, which is what a white plate or napkin is meant to do.