The production of chocolate is a 15 billion dollar business and Americans eat about 12 pounds of chocolate each year. Chocolate does have a shelf life; over time it can get a whitish appearance called "bloom," which makes it less desirable to many consumers. Understanding what causes bloom is thus an important concern for producers of chocolate. In this activity, chocolate has been stored in several conditions to see which conditions are more or less associated with bloom. Students view atomic force microscopy images of five samples of chocolate, examine the samples' appearance, and then taste the five samples.
If you have any questions about this activity, please contact Joe Muskin at (217) 265-6481 or by email at firstname.lastname@example.org.
Teacher needs: LCD or overhead projector; access to a clean incubator is optional.
Instructor's guide containing all relevant information to conduct the activity.
Presentation for teacher to introduce the activity to students.
Worksheet that accompanies the activity.
Images of chocolate stored in 4 ways plus the control.
Images of the plate toppers you can use for this activity.
Make sure there are no allergies to the ingredients in chocolate before you begin. Otherwise, involvement in this activity poses minimal safety issues.
Thanks for Nikki Engles for technical information and assistance in the early stages of this activity's development. Thanks to Scott Maclaren for the use of his wonderful AFM images. Thanks to the Imaging Technology Group at the University of Illinois Urbana-Champaign for the images used in the PowerPoint presentation. Thanks to Scott Robinson and Daniel Weber and the Imaging Technology Group for the back-scattered electron image of an ant.
Joe Muskin, Lia Andrae, Carrie Kouadio