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Testing Liquids for Starch

Testing Liquids for Starch. Food Chemistry Lesson 3. Think & Wonder. Are you ready to learn how to do your first chemical test? Today you will test five liquids. Which one contains the nutrient starch? How can you tell? What is a “positive” test?. Testing Liquids for Starch.

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Testing Liquids for Starch

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  1. Testing Liquids for Starch Food Chemistry Lesson 3

  2. Think & Wonder Are you ready to learn how to do your first chemical test? Today you will test five liquids. Which one contains the nutrient starch? How can you tell? What is a “positive” test?

  3. Testing Liquids for Starch • Starch belongs to the category of nutrients known as carbohydrates. • Starch is made up of a long, linked chain of simple sugars. These sugars are called glucose. starch glucose

  4. Sources of Starch • During digestion, our body breaks down starch into glucose. • Glucose then provides energy for our muscles and brain. • Major sources of starch: • Rice, corn, and potatoes digestion

  5. Fiber • Some starchy foods are also high in fiber. • Fiber is indigestible material that helps move matter through the digestive tract. • Sources of fiber • Fruits, vegetables and whole grains fiber

  6. Testing • Today we will use iodine to establish a positive and negative test for starch. • These tests will indicate the presence or absence of starch in the liquids. presence absence

  7. Testing • Positive test results – Test that reveals a change from brown color to purple. Indicates the presence of starch. Indicated by a (+) on your data sheet. • Negative test results – Test that reveals no change in color. Indicates absence of starch. Indicated by a (-) on your data sheet. positive test negative test

  8. Materials For each group: • 1 lab bag • 1 food bag • 2 six section test trays • 1 bottle of iodine • 1 box of toothpicks • 1 liquids bag • Water • Corn starch • Corn syrup • Corn oil • milk For each student: • LRB • Record Sheet 3-A

  9. Class Liquids Test Prediction Table

  10. Class Liquids Test Results Table

  11. Procedure • Place one drop of iodine in section 6 (control) • Place three drops of each liquid into a section of the testing tray. Be sure you know which liquid is in which section. • Slowly add ONE drop of iodine to sections 1 - 5. • Stir with a toothpick. Record your results complete with your observation • Continue process with each liquid. control

  12. Closing Activity Answer the post lab questions in your LRB. Share group findings on class control sheet.

  13. Update your Table of Contents

  14. Extension • Does the color change indicating a positive test for starch depend on the amount of starch present? • How can you answer this question? • Design an experiment to solve. • Include: • Hypothesis (prediction) • Materials • Procedure • Conclusion experiment hypothesis procedure conclusion

  15. Clean-up Replace ALL items into the bag. When you finish, place your tray in the soapy liquid prepared for you in the sink.

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