Final answer:
Holding a starchy substance in the mouth for a few minutes will break down starch into smaller units, making the food taste sweet.
Step-by-step explanation:
When you hold a starchy substance in your mouth for a few minutes, it starts to break down into smaller units due to the enzyme called amylase, which is found in saliva. This process is known as digestion. As the starch breaks down into smaller pieces, it releases sugars. These sugars are what make the food taste sweet. So, holding a starchy substance in the mouth for a few minutes will make the food taste sweet.