Does the Flexibility of Gelatin Depend Upon the Amount of Water?
Category: Biology—Food Science
Project Idea by: Benjamin Skrabanek
Gelatin is a substance made of animal protein. Proteins are nutrients made of one or more chains of chemicals. The protein chains forming gelatin are like long, tangled strands of sticky spaghetti. Gelatin is flavored and colored to make jiggly desserts and is also used in marshmallows and other foods.
When gelatin is mixed with hot water, the protein chains separate from one another and can freely move about. As the mixture cools, the proteins begin to recombine by forming bonds (the forces that hold chemicals together) between the chains. The chains connect in a haphazard way, forming a tangled web in which water in the mixture is trapped. This process is called gelling, and the semisolid that is formed is called a gel. The protein web of the gel gives it shape, and the trapped water causes it to be flexible (able to change its shape in response to a force, then recover its original shape when the force is removed); that is, the gel can jiggle. A project problem might be, "How does the amount of water in a gel affect its flexibility?"
Clues for Your Investigation
With adult help, follow the basic directions on a package of dessert gelatin. Make changes only in the amount of water mixed into the dry gelatin for each testing. Keep the amount of gelatin the same and vary only the amount of water for several different gels. Create a scale for testing the flexibility of the gels. For example, shake the gels after they have cooled, and determine on a scale of 1 to 10, with 1 being the least flexible, how easily they return to their original shape.
Independent Variable: Amount of water
Dependent Variable: Flexibility of gel
Controlled Variables: Type of dessert gelatin, amount of dry gelatin used, temperature of water, cooling time, testing procedure for flexibility
Control: Gel made with the median amount of water
Other Questions to Explore
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.