It's time for chemistry in the kitchen! In this issue of Science Explorations, watch a project video and learn more about food chemistry as you do three simple experiments to test food for vitamin C, glucose, and fats & oils
Turn your kitchen into a laboratory as you explore the chemistry of food! Food comes in so many shapes, textures, colors, and delicious flavors, but it all serves one purpose: to give your body the nutrition it needs to survive. Different foods provide different nutrients, like vitamin C, carbohydrates, and lipids. Can you figure out what you're getting from your favorite food? Use these three simple chemistry tests to sleuth it out. (Note: Adult supervision required when working with chemicals.)
Stop the Scurvy - Vitamin C Test
What foods have vitamin C? Do oranges have more than lemons? Do a simple chemistry test to find the answer.
>> Check out our project videoto see the test in action!
Vitamin C is a vital nutrient for humans that aids our immune system and helps prevent disease. Many animals can make their own vitamin C, but humans must get it from their diet, which is why the vitamin C content of the food we eat is important. At one time a disease called scurvy was common among sailors, because they had no access to fruits and vegetables at sea. Scurvy is caused by a lack of vitamin C.
Indophenol is an indicator that turns colorless in the presence of vitamin C. The fewer drops of juice you need for the color change, the higher the vitamin C content in the juice. Which fruits had the most vitamin C? Do you think different preserving methods (canning, drying, freezing) has an effect on vitamin C? Do some more tests to find out!
Sugar and Starch - Glucose Test
Glucose is a simple sugar (carbohydrate) that plants produce by the process of photosynthesis. It is the primary source of energy for our body's cells, and is able to enter our bloodstream quickly to provide energy right away. Without glucose, our bodies wouldn't function! Plants store extra glucose in a more complex carbohydrate called starch. During digestion, our bodies break the starch back down into glucose for our cells to use as an energy source.
In this project you saw that process in action. Saltine crackers have lots of starch. When you chewed one of the crackers, an enzyme in your saliva, called amylase, started to break the starch down into glucose. Benedict's solution is a glucose indicator that changes colors based on how much glucose is present. Green, yellow, orange, or red indicates the presence of glucose. The color difference in your two test tubes proves that the chewed-up cracker contained glucose while the other didn't.
Looking for Lipids - Fat Test
Lipids are fats and oils, made of molecules that don't dissolve in water. They are very important for our body functions because they transport vitamins, help form cell walls, and store energy long-term. Eating too much fat can be very unhealthy, but every good diet will contain a moderate amount. How many of the foods you tested contained lipids? Try comparing food that has a "regular" version and a "low-fat" (or "non-fat") version. Is there a difference between the spots left by skim milk and whole milk?
Learn about the food groups with this site from the US Department of Agriculture.
Do more chemistry tests to learn about lactose and lactose intolerance.
Learn more about how food works with this great biochemistry site.