INTRODUCTION In this lab, you will investigate the properties of organic compounds derived from foods we eat. Each of these compounds, all of which contain carbon, oxygen and hydrogen, has distinct physical and chemical properties whose reactions can be used to identify them. The three major organic compounds which you will study are carbohydrates (both simple sugars and starch), lipids (fats), and proteins.

You will observe how chemical tests are used to identify their presence. Then you will observe these same tests on several foods and identify which organic molecules they contain.

PART 1: TESTS FOR PRESENCE OF ORGANIC NUTRIENTS In this part you will observe chemical tests used to identify the presence of sugars, starches, fats and proteins. First, you will observe what happens when the organic molecule is absent.

This will demonstrate a negative test. Second, the organic molecule will be added and the test repeated. Record the positive test results in the OBSERVATIONS chart below. • Test for simple sugar – Observe what happens with Benedict’s solution. • Test for starch – Observe what happens with Iodine. • Test for fats and oils – Observe what happens with Sudan IV. • Test for proteins – Observe what happens with Biuret’s solution.

OBSERVATIONS:

Organic Compounds Positive Test Results simple sugar starch fats proteins

PART 2: IDENTIFYING ORGANIC NUTRIENTS IN FOODS The foods you eat contain carbohydrates, fats, and proteins, all of which are necessary for the maintenance of cellular activities in all living organisms. These nutrients are usually combined in the foods you eat so that you may not recognize them. You will observe the tests in Part 1 to help you identify the organic compounds in a particular food.

Record your findings in the chart by placing a + (positive) or – (negative) for each nutrient in the food you test.

OBSERVATIONS: FOOD SIMPLE SUGARS STARCH FATS/OIL PROTEIN potatoes juice nuts eggs salmon milk

ANALYSIS of DATA & CONCLUSIONS: 1. Explain why you think some of your foods tested positive for more than one organic nutrient.

2. Provide a summary of what you learned from doing this investigation.

3. What real-life applications are there from knowing what you do now after conducting this investigation?