Sit down in a quiet room in a chair where you will not be disturbed. Close your eyes. Imagine yourself in a bakery or other food establishment(don’t visualize yet). Choose a food item at random. Hold an imaginary taste in your mouth for a period of 3 seconds. Practice this until you become proficient at it, and holding a taste in your mouth for a period of 3 seconds becomes easy. Increase the amount of time to 5 seconds and become proficient. After you have done this, increase to 10, and so on.
Do this exercise until you can imagine a taste for 30 seconds with no breaks. Remember to note your progress in your journal.