What really happens when coffee goes decaf? Discover the truth of the often-misunderstood world of decaffeination as we peel back the layers to reveal the surprising history and cutting-edge science that creates your favorite caffeine-free brew. Discover how decaf coffee went from using dangerous chemicals like benzene to today's revolutionary supercritical CO2 process. Our expert guest, Dr. BJ Yoblinski, an inorganic chemist, demystifies complex concepts, explaining what a supercritical fluid is and how it precisely extracts caffeine from green coffee beans. From early accidental discoveries to modern bean to cup innovation, this episode offers a fascinating look at the coffee science ensuring your decaf is both safe and delicious. Tune in to understand the intricate industrial process and the surprising fate of the extracted caffeine!

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5 Takeaways:

1. Early Decaf Was Risky: The very first decaffeination methods, including those used for Sanka, involved highly toxic chemicals like benzene (a component of paint stripper and gasoline).

2. Supercritical Fluids are "Fourth State" Wonders: Beyond solid, liquid, and gas, substances like CO2​ can become a "supercritical fluid" under specific temperature and pressure, exhibiting properties of both liquid and gas, making them ideal solvents.

3. CO2​ is a Selective Solvent: In its supercritical state, carbon dioxide preferentially dissolves caffeine from coffee beans, leaving the flavor compounds largely intact.

4. Modern Decaf is Safe & Clean: The widespread adoption of the supercritical CO2​ process replaced older, more dangerous chemical methods, leading to a safer and better-tasting decaf coffee.

5. Extracted Caffeine Has a New Life: The caffeine removed from decaf coffee beans is purified and primarily sold to the soft drink and power drink industries.

3 Discussion Questions :

1. Were you surprised to learn about the early decaffeination methods? What was the most shocking fact for you?

2. Had you ever heard of a "supercritical fluid" before this episode? How would you explain it to a friend now?

3. Do you drink decaf coffee? Does knowing the science behind the CO2​ process change your perception of it?

Glossary of Terms

• Atmosphere (atm): A unit of pressure, approximately equal to the average atmospheric pressure at sea level. In the context of decaffeination, high atmospheres of pressure are used to achieve a supercritical state.

• Benzene: An organic chemical compound, historically used in the early decaffeination process for Sanka. It is a known carcinogen (cancer-causing substance) and is also found in paint stripper and gasoline.

• Caffeine: A natural stimulant found in coffee beans, tea leaves, cocoa, and other plants. It is the primary target for removal in the decaffeination process.

• Carcinogen: Any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). Benzene is identified as a carcinogen in the episode.

• Carbon Dioxide (CO2​): A colorless, odorless gas. In the supercritical CO2​ decaffeination process, it is transformed into a supercritical fluid to selectively extract caffeine.

• Critical Point: The specific temperature and pressure at which the distinction between liquid and gas phases disappears for a substance. Above this point, the substance exists as a supercritical fluid.

• Decaffeination: The process of removing caffeine from coffee beans.

• Degassing Chamber: A component in the industrial supercritical CO2​ decaffeination process where the pressure and temperature are lowered, causing the CO2​ to revert to a gas and leaving solid caffeine behind.

• Extractors (Continuous Extractors): Tall, industrial vessels (described as 60-70 feet high) used in the supercritical CO2​ process where green coffee beans are soaked in the supercritical CO2​ to dissolve the caffeine.

• Green Coffee Beans: Unroasted coffee beans, which are the starting material for the decaffeination process.

• Inorganic Chemistry: A branch of chemistry that deals with the properties and reactions of inorganic compounds (those not containing carbon-hydrogen bonds, or containing them in simple forms). Dr. BJ Yablinski's expertise is in this field.

• Methylene Chloride: A chemical solvent that was used in decaffeination processes after benzene. While considered safer than benzene, it was also a suspected carcinogen and could impart a chemical taste to the coffee.

• Sanka: A brand of decaffeinated coffee, historically significant as one of the first commercially successful decaf products in the U.S., originally decaffeinated using benzene.

• Supercritical Fluid: A state of matter that is beyond the critical point, where it has properties of both a liquid and a gas. It can fill a container like a gas but has a density and dissolving power similar to a liquid.

• Supercritical CO2​ Decaffeination Process: The modern, industrial method of removing caffeine from coffee beans using carbon dioxide in its supercritical fluid state. This process is highly selective for caffeine and is considered safe and clean.

• Swiss Water Process / Mountain Water Process: Mentioned as "chemical-free" decaffeination methods, distinct from solvent-based methods. These were developed later than the chemical solvent methods.

Decaffeination Timeline:

• 1903: The first decaf method is patented by a German merchant. This method accidentally discovered that soaking coffee beans in seawater removed caffeine, but the commercialized version used benzene as the solvent.

• Early 1900s: Benzene-based decaffeination becomes commercially available (e.g., Sanka in the U.S.).

• Mid-20th Century (Post-Benzene): Safer chemical solvents like methylene chloride are developed and used for decaffeination, replacing more dangerous early methods. However, these still posed some health concerns and could affect coffee taste.

• Late 1960s: German chemist Kurt Zossel makes a breakthrough in developing the supercritical CO2​ decaffeination process.

• 1980s: The supercritical CO2​ process is largely developed and refined for industrial application.

• 1990: The supercritical CO2​ process becomes an industrial standard for decaffeination, largely replacing older, less safe chemical solvent methods like those using methylene chloride.

• Ongoing: Chemical-free methods like the Swiss Water and Mountain Water processes continue to be utilized alongside the supercritical CO2​ method, offering various options for decaf production.