高考英语词汇积累系列：流行话题阅读语境识词4500 UNIT 64　THE STORY OF CORN WORD版.doc

1、Unit 64The Story of CornBefore 1492, when Columbus discovered America, no one living in Europe knew corn existed. Up to this time, corn grew only in the Americas. Scientists believed corn was originally cultivated by Indians in the highlands of Mexico thousands of years ago. American Indians were gr

2、owing corn in many parts of North America log before the first arrival of European explorers and traders. Christopher Columbus and the explorers that followed him took corn back to Europe and introduced it to the world. Native American Indians taught European colonists to grow many varieties of the

3、corn including yellow, re, blue, pink, and black kernels. As time went on, the new settles to America began to depend on corn as one of the most important farm crops. American farmers have always wanted to grow strong healthy corn plants that yield as much as possible. In the later 1800s scientists

4、worked on the development of hybrid corn. This research led to better varieties of corn and higher yields.Did you know corn is used to help produce antibiotics, baby foods, condensed milk, some fruit juices and even peanut butter? From the corn syrup in your soda pop to thousands of products - anima

5、l feed, human food, drugs, cosmetics, corn sweetener and cleansers, just to name a few. Beyond its food and consumer product uses, corn is replacing petroleum in many industrial applications, from plastic containers to clean-burning ethanol. Because corn products are a biodegradable and renewable na

6、tural resource, they are better for the environment than their petroleum counterparts.Corn and products made from corn improve the lives of Americans in thousands of little way. If corn and its products werent available, many common products would be less useful, more expensive, even unavailable. He

7、re are some examples of the little annoyances and bigger problems Americans would face without corn: No freezing pizza. Freezing pizza is a problem, because the moisture in the sauce can migrate into the crust, making it so soggy that its unappealing to eat. Modified corn starch is used to provide a

8、 barrier that prevents water migration and keeps the crust crisp. On a low-fat diet? Say thank you for corn. Many low-fat foods depend on corn-derived food starches to provide qualities that used to come from fats. Examples include everything from low-fat salad dressing to baked goods and meat produ

9、cts. Frustrating wallpapering. If youve installed wallpaper, you know how important it is to have time to adjust each strip accurately. Repositioning is possible because the wallpaper paste is made with corn starch modified to slow down its adhesive action. Brown lettuce leaves. Many fruits and vege

10、tables start to turn an unattractive brown once theyre cut and exposed to air. Citric acid, recognized as a safe food ingredient, can prevent browning and much of the US supply of citric acid is made from corn sweeteners. No coloring for kids. Whether playing with chalk on the sidewalk or crayons in school, American kids rely on corn. Corn starch is used to help such products hold together better when in use.