Look no further than your Thanksgiving feast for an opportunity to use chemistry to explore the world! Using chemicals, foods, and some basic lab items, you can test your meal for starch, protein, and fat! You could also use our complete Chemistry of Food Experiment Kit to perform these and other experiments. Be sure to put on your personal protective equipment before you start experimenting!
In this experiment, test for starch using Lugol’s iodine. First you'll made a solution using solid foods. If using liquid foods, this won't be be necessary. The solution will turn blue-black if starches are present.
Extra glucose is usually stored in a more complex carbohydrate called starch. When we eat foods with starch, our body breaks down the large starch molecules into simple sugars, like glucose, to use for energy. The energy from starch, along with other carbohydrates, allows us to think, move, and do everything else, from reading a book to running a race. Starch is part of a healthy diet, especially when it comes from whole-grain foods that also contain vitamins and minerals.
In this experiment, test food for protein using Biuret reagent. The blue solution changes to pink-purple when it reacts with protein.
Protein strengthens your muscles and organs, helps your immune system, and controls many processes inside your cells. Your body also uses specialized protein molecules to make red blood cells, which carry oxygen to all parts of your body. Proteins are large, complex molecules made up of smaller “building blocks” called amino acids. Digestion breaks proteins into individual amino acids that come together to form new proteins that fit the needs of each individual cell. Protein is an essential part of our diet, but because it is complex, it’s difficult to digest, so we can only eat small amounts every day. Protein doesn’t get stored in the body, though, so it is important to eat it regularly.
Use Sudan III to identify the presence of lipids (fats) in liquids. It stains fat cells red.
Fats and oils are both lipids. Lipids are molecules that are insoluble (won’t dissolve) in water. They transport vitamins, help form cell walls, and store energy long-term. Fats contain at least twice the amount of energy as carbohydrates and proteins. They do not, however, provide instant energy like starch and glucose do, but are used as storage. Eating too much food with fat or oil can be unhealthy, causing heart problems, since lipids flow through the bloodstream and can block your arteries. A healthy diet should include a small amount of lipids, balanced by eating small amounts of protein everyday.