Identification of Macromolecules in Food Lab Report

Macromolecules in Food INTRODUCTION The most common macromolecules found in living organisms are lipids, carbohydrates, proteins, and nucleic acids. (Hillis et al 2011). Macromolecules are normally containing two or more monomers in them and their main functions are to store energy. Starch is a huge molecule made up of hundreds of simple sugar molecules (such as glucose) connected to each other. Most foods are known to be combinations of macromolecules.

METHODS The tests performed were iodine testing for starch, Benedict’s test for glucose, the grease spot test for lipids, and the CuSO4’s test for protein.The pH indicator’s detection is based upon observing a chemical change that takes place most often a change in color. The Starch test was used for the presence of starch. In this instance, the distilled water is a negative control for the test, and a known glucose solution is a positive control. This was a simple test in which iodine is added to a given solution in test tube. If iodine added to a solution turns black-blue than starch is present (positive test).

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If the solution remains light yellow color, there is no starch present (negative test).We use the Benedict’s test for Simple Sugars to test for the presence of glucose. Benedict’s reagent is clear blue. A positive reaction in a Benedict’s test is the change of the clear light blue (negative test) solution to an orange solution in boiling water. This color change indicates the presence of glucose in a given solution.

As we all know from experience, lipids leave translucent grease spots on unglazed brown paper bags. We put a small drop of oil on a paper towel, next to it put a small drop of water, and let sit for few minutes to dry. Once dry, the fats will leave a grease spot behind.This can best be seen when you hold the paper up to a light source. The last macromolecule we explore in this lab is protein.

In this lab we will test for the presence of protein using the CuSO4 test. A positive reaction in this test is the change of the light blue solution to a purple solution. http://www. saddleback. edu/faculty/thuntley/bio3a/labs/bio3alabmolecules. pdf INDICATOR MACRO-MOLECULE NEGATIVE TESTPOSITIVE TEST Benedict’s solutionsimple carbohydrateblueorange Iodine solutioncomplex carbohydratedark redblack Biuret solutionproteinblueviolet, black Sudan IVlipiddark redreddish- orange