Biology/Scholars Biology Testing Foods for Organic Compounds Lab

Introduction

Carbohydrates, proteins, and lipids provide your body with energy to carry on life activities. These compounds are present in the plants and animals you use as food. In this lab, you will test for specific biological compounds and then determine if those compounds are present in ordinary foods. To do this you will use indicators to test for three organic compounds. Indicators are dyes which change color in the presence of certain organic compounds.

 Benedict’s solution turns from blue to orange in the presence of glucose.  Iodine turns from amber to bluish black in the presence of starch.  Biuret solution turns from blue to lilac (light purple) in the presence of protein.  Sudan IV will change the color of a fat to red in the presence of lipids.

Purpose: determine the presence of organic molecules in common foods.

Procedure:

1. Go to pdecandia.com. Select the Biology or Scholars Biology page. Click on the Organic Chemistry picture link. Click on the link in the lab section for “Testing Foods for Organic Compounds”. 2. Click on each of the links in order and follow the directions in each section. 3. When you are done with the carbohydrate section, go on to the proteins, then the fats section and complete each part of the lab. Record your answers for each exercise in the data sheet. 4. Once you are finished with the organic compounds tests, move on to the foods section of the lab and record your results for each of the foods in the data table. Name ______Biology/Scholars Biology Testing Foods for Organic Compounds Lab Data Sheet 1. When we test water, what should the result always be? What is the purpose of testing water for each organic

molecule?

2. What does an indicator do?

Simple Sugar Test 1. What organic molecule does Benedicts reagent test for? 2. What color is a negative result? A positive result?

Carbohydrates Section 1. What organic molecule does iodine test for? 2. What color is a negative result? A positive result?

3. People with diabetes are instructed to avoid foods that are rich in carbohydrates. What types of foods should

people with diabetes avoid?

Proteins Section 1. What organic molecule does Biuret reagent test for? 2. What color is a negative result? A positive result?

3. List five foods that contain proteins.

Lipids Section 1. What organic molecule does Sudan IV reagent test for? 2. What color is a negative result? A positive result?

3. List five foods that contain lipids. Food Section Data Table Record as follows: + positive result - negative result

Food sample Benedict’s test Iodine test Biuret test Sudan test + / - + / - + / - +/ - (glucose) (starch) (protein) (lipid)

Potatoes

Orange juice

Nuts

Eggs

Salmon

Milk

Conclusion You are a dietician and have to recommend a balanced food plan for a customer. Using your knowledge of the organic molecules contained in food from this lab, write out a three meal menu with foods for each meal that contain the three organic molecules, proteins, carbohydrate, and lipids. Be sure to write the meal, each food and list the organic compounds found in each food.

Breakfast Food Organic Molecule in each food

Lunch Food Organic Molecule in each food

Dinner Food Organic Molecule in each food