Category Archives: Food Nutrition

Food Nutrient Analysis


Food Nutrient Analysis

Purpose: The purpose of this lab was to test for the presence of carbohydrate, starch, lipid, protein, and vitamin C using a variety of experiments.

Procedure: There were multiple procedures depending on which nutrient was being tested for. In order to test for carbohydrate the procedure included: 1) Measure 5 mL of distilled water in a plastic measuring cup. Pour the water into test tube 1. 2) To test tube 2, add 5 mL of water and 10 drops of sugar solution. 3) Add 20 drops of Benedict’s solution to both test tubes. 4) Carefully place both test tubes upright in the hot water bath and let them heat for 10 minutes. 5) As the test tubes heat, look for any color changes in the solutions. 6) After 10 minutes, record the color of each solution. For the best view, look downward through the top of each test tube or hold the test tube against a sheet of white paper. In order to test for starch the procedure included: 1) Measure 5 mL of distilled water in the plastic cup. Pour the water into test tube 1. 2) To test tube 2, add 5 mL of water and 20 drops of potato starch solution. 3) Add 4 drops of iodine-potassium iodide solution to both test tubes. 4) Observe the test tubes closely for 30 seconds. 5) Watch for any color changes in the test tubes. 6) Record the colors below. For the best view, look downward through the top of each test tube or hold test tube against a sheet of white paper. In order to test for lipid the procedure included: 1) Measure 5 mL of distilled water in the plastic measuring cup. Pour the water into test tube 1. 2) To test tube 2, add 5 mL of water and 20 drops of vegetable oil. 3) Add 20 drops Sudan IV fat stain to both vials. 4) Gently shake the two test tubes and then set them aside. 5) After 3 minutes, observe the vegetable oil later and note the color. 6) Record the colors below. For the best view, look downward through the top of each test tube or hold the test tube against a sheet of white paper. In order to test for protein the procedure included: 1) Measure 5 mL of distilled water in the plastic measuring cup. Pour the water into test tube 1. 2) To test tube 2, add 5 mL of water and 10 drops of albumin protein solution. 3) Add 20 drops of Biuret reagent to each test tube. 4) Use a stirring rod to gently stir the two test tubes. Use a different stirring instrument every time, or clean the rod well between uses. 5) Look for any color changes in the solutions. 6) Record the colors below. For the best view, look downward through the top of each test tube or hold the test tube against a sheet of white paper. In order to test for vitamin C the procedure included: 1) Add 20 drops of 2,6 dichloroindophenol solution to test tube 1, and 20 drops to test tube 2. 2) Add 1% ascorbic acid solution, 1 drop at a time, to test tube 1. Count how many drops you add, and continue until the 2,6 dichloroindophenol becomes clear. 3) To test tube 2, add distilled water in drops equal to the amount of 1% ascorbic acid solution that was added to test tube 1.

Results: Carbohydrate- The test showed a positive result for sucrose. One of the test tubes showed a positive test for a monosaccharide as well.

Starch- One of the test tubes showed a positive test for starch. One of the test tubes changed color from bright yellow to dark blue.

Lipid- One of the test tubes showed a positive test for lipid. The Sudan IV stained the lipid layer a darker pink.

Protein- One of the test tubes showed a positive result for protein. The Biuret reagent changed from blue to purple/pink.

Vitamin C- One of the test tubes showed a positive result for Vitamin C. The solution changed from blue to clear.

Conclusion: The results from these tests demonstrated what the presence of these nutrients resembles. Each separate test done throughout this experiment included two different test tubes, and one of the two consistently showed a positive result for each specific nutrient that was tested. This experiment helped breakdown the makeup of each nutrient in order to understand them in their simplest form.

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