In my chemistry class we finish the school year with a unit called "The Chemistry of Coffee" where we explore the chemical reactions involved in roasting coffee and discover how roasting green coffee beans into different types of roasts produces different compounds and ultimately different, unique flavors. My students look forward to "The Chemistry of Coffee" every year because it is a way for them to connect science with their everyday lives.
The foundation of the labs and lessons of The Chemistry of Coffee is roasting coffee. By controlling variables and experimenting with other variables students are able to create their favorite brews and, in the end, enter their coffee into The Coffee Cup, the final lab competition of the year.
As it turns out, brewing coffee is quite easy - the difficult part is producing good tasting, enjoyable and delightful brews. But, with a little equipment and some trial and error, you can make fantastic coffee right from the comforts of home...or, if you have one, from the comforts of your chemistry lab!
Supplies Needed to Roast Coffee at Home
Whirley Pop Popcorn Popper (recommended)
Air Popcorn Popper
Digital (convenient but may break at high temperatures)
Gas (recommended for classroom labs with natural gas lines)
Butane (recommended if no natural gas lines are available)
Electric (convenient but doesn't always produce enough heat for dark roasts)
Coffee Press (recommended)
Build Your Own Siphon Brewer (instructions from Beals Science)
Raw Coffee Beans
How to Roast Coffee Beans at Home
**Note: The instructions listed below are from "The Chemistry of Coffee" a free unit of lesson plans and labs available here at BealsScience.com. The roasting instructions are for the recommended supplies listed above.**
Click here for all of "The Chemistry of Coffee" lessons and labs.
Introduction: In science, experimenting requires that you control all of the variables involved. The procedure below is a good experimental procedure to learn how to operate the equipment. Once you've learned the basics, you can roast as many beans as you'd like and roast lighter or darker - whichever is your preference.
Procedure: One cup of coffee requires 1 tablespoon of beans per 6 oz of hot water. These instructions are for a practice roast using 2 cups of coffee that you can taste to see how you need to make adjustments to your roasting process. We will attempt to a roast a “Full City Roast” where the bean is on verge of 2nd crack and has reached an internal temperature of 228 °C (444°F).
1. Measure out 32 grams of green coffee beans (each cup requires ~10.6 g or .38 oz)
2. Turn on burner and begin warming the pan.
3. Keep temperature above 175° C and below 190° C (350-400° F), stabilize this
temperature before adding beans.
4. Add beans. Stir constantly and shake periodically.
5. Listen for the first crack. Record the time and temperature when you hear it.
6. Remove beans at 11 min 30 sec (time when Full City Roast should be achieved) and
carefully pour them into the colander. Shake colander over large trash can so beans
7. Clean up equipment while beans cool by wiping out roaster and colander with a dry
Ready to try new roasts? Click here for help on making all types of coffee roasts.