Capsaicin Extraction from Chili Peppers

This month's lab can be used as a biology lab or chemistry lab all you have to do is choose your emphasis. There is a lot great science in this activity.

• performing a serial dilution
• extracting a medicinal compound from plant materials
• using Scoville units to determine the heat index of various peppers.

Click here for the pdf

Background

The chemicals that cause the sensation of heat when you eat a pepper are called capsaicinoids.  Capsaicin being the main capsaicinoid found in chili peppers.  This chemical is so hot that just one drop mixed with 10,000 drops of water will cause the tongue to blister.

The hotness of a chili pepper is measured in Scoville units. These units were invented by Wilbur Scoville, a pharmacist, in 1912. To determine the “hotness” using Scoville units, a panel of 5 tasters sample extracts of the peppers that are diluted in sugar water. The dilution that can be detected by 3 of the 5 tasters is considered the heat level of the pepper.

The ratio of the extract dilution is the Scoville unit. For example, the jalapeno is usually detected by 3 of 5 tasters when diluted at a ratio of 1/2500 to 1/5000; the Scoville unit for the jalapeno is 2500 to 5000. Just to compare, the habanero pepper can have 100,000 to 300,000 Scoville units.

In this lab, you will be using a variation of Scoville’ s test to determine the hotness of several types of capsicum peppers.

Materials

•  glass mortar & pestle  
• 5  2-dram vials with caps 
• graduated pipettes  
• latex gloves
• 5% sucrose solution  
• 95% ethanol (everclear)
• electronic balance 
• weighing boat  
•  knife    
• various chili peppers

Safety Precautions

• Wear safety goggles and latex gloves. 
• Do not contaminate your equipment, keep it safe for consumption.
• Keep your hands way from your face and eyes.  
• Make sure you wash your hands after the lab.

Warning: Do NOT use laboratory ethanol. Use Everclear.

Notes

You can easily substitute small craft paint containers for the vials.  You can substitute glass bowls for the mortars and you can make pestles out of PVC pipe.

Click here for the pdf