LESSON 3: Starch Your Day Right!
SUBJECT: Science
OBJECTIVE: Students will do a simple experiment that produces raw starch, and will then learn about commercial separation in a corn refinery.
MEASUREMENT: Students will understand the refining process for corn, and will appreciate that nothing is wasted! They will also know where cornstarch comes from. They'll be ready to learn some of the uses of this starch. (See Unit 9, Lesson 1 and Unit 7, Lesson 4).
BACKGROUND FOR TEACHERS:
A key component of the corn kernel is starch. (See Unit 9, Lesson 2)
Cornstarch
- is the food source for the germinating seed.
- is a source of many, many food products for people (See Unit 9, Lesson 1).
- is a key ingredient in the production of ethanol (See Unit 7, Lesson 1).
- is a key ingredient in the production of biodegradable plastics (See Unit 7, Lesson 4).
The refining process described in this lesson is a "wet milling" process. This process soaks the kernels until the components can be separated mechanically. The germ is removed for corn oil, and the starch is removed for industrial or food uses, ethanol, biodegradable plastics, or a variety of other high value consumer products. The remaining components are mainly used in animal feed.
A "dry milling" process is a lower cost option if corn is being processed for ethanol. In that process, the corn is ground into flour, and the entire product goes through the fermentation procedure. After the ethanol is distilled off, the remainder is dried and sold as a 30 percent protein product called Dried Distillers Grains (DDGs).
STUDENT ACTIVITIES:
1. Ask students to read the story David Makes Cupcakes, paying close attention to the last several paragraphs which describe many of the food products made from corn ("There is cornstarch in the sprinkles.")
2. Conduct the experiment explained on the following worksheet to demonstrate to students the separation of starch from the corn kernel. (Worksheet 1)
3. Use the following handout to explain the three major steps in commercial corn refining: steeping, germ separation, and starch and gluten separation. This may make more sense to students if it is used in conjunction with the Kernel Surgery (Unit 9, Lesson 2) experiment where students learn the four major parts of a corn kernel.
The handouts state that the most important refined corn products are corn sweeteners, starch, oil, ethanol, and feed products. The sweeteners, starch, and oil are discussed in this unit (Unit 9). Ethanol is discussed in Unit 7. Animal feed products are discussed in Unit 6. These might help the students understand what happens to the corn after it's refined! (Example 1)
4. Older students can complete the fill-in-the-blank worksheet and essay questions. (All can be answered from the above handouts.)
5. If possible, schedule a field trip to a corn refinery or any corn processing plant to see actual processing of food products, ethanol, biodegradable plastics, etc. |
KEY ISSUES
