Great Biology Lab: Testing Foods for Organic Compounds

It's a little messy, but my students love it!

Today, we completed a lab that is always a favorite for my students.   We have been studying the groups of organic compounds:  Proteins, lipids, carbohydrates and nucleic acids.  So today, my students were given the task of determining which of the organic compounds are found in various foods.

We ran 5 different tests.  We tested for glucose using Benedict's solution. We tested for starch using iodine.  We tested for Vitamin C using indophenol.  We tested for protein using Biuret reagent.  And we tested for lipids by using the brown lunch bag test.

Before giving the students any foods to test, it is best to allow them to "practice".  My students were given a starch solution and told to test it for starch.  Amazingly, it contained starch!!  (haha)  The purpose of this is to let the students see what the positive tests look like so that when the foods are tested, they know and can recognize the results they are getting.

I had my students test cereal, egg whites, egg yolks, milk, yogurt, celery, potato,  and pineapple juice.  Solutions can easily be made by placing the food in a blender with a little water.

There is nothing quantitative about this lab, and that is a drawback, but students really love to perform these simple tests.

Biology Lab: Testing foods for Organic Compounds.