Watching TV or playing with a mobile phone can be a distraction for the child. Keep all the gadgets away during mealtime. Let the child concentrate on the food.
This will help the child understand the taste of each food item.
Moreover, switching off TV also keep your child away from advertisements that promote sugary and less nourishing food.
Some children might dislike specific food items as they might be allergic to it.
Keep a close watch on your child and see whether he has a bellyache or even throws up after eating a particular food. This is particularly so after consuming dairy products or food containing gluten. If so, it is time you consult a pediatrician to rule out a possible food allergy.