Explain how corn is found in a variety of food in the supermarket?

According to the book, corn can be found in a variety of foods in the supermarket. It usually turns up as a processed ingredient.
The author gives the example of chicken nuggets: the corn is present in the "modified corn starch" that is used to keep the nugget's constituent ingredients together. There may also be corn flour in the batter, and the nuggets may have been fried in corn oil.
Many customers also drink soda. The most popular sweetener used in a wide variety of sodas is high-fructose corn syrup. High-fructose corn syrup is also found in many types of fruit beverages. Additionally, if customers purchase beer, the beverage may have been made from fermented corn. Traditionally, beer manufacturers use barley as the main ingredient; however, many also use corn, a cheaper alternative to barley.
The author says that corn can be found in a variety of foods in the form of modified corn starch, crystalline fructose, high-fructose corn syrup, caramel coloring, and dextrose. In total, the author asserts that there are now forty-five thousand food items in American supermarkets that contain corn.