Methylene Chloride, also known as dichloromethane (CH2C12), is a colorless and volatile liquid with a sweet, penetrating, ether-like smell. It's an organochloride compound and is used as a highly effective solvent in various industrial processes. It is non-combustible and is also obtained naturally from oceanic sources (macroalgae), wetlands, volcanoes, etc.
It's not mixable with water, but it is miscible with various other organic solvents. It only produces toxic chloride fumes in extremely high temperatures. Because of its nature, it can be dissolved in numerous organic solvents. Combine that with methylene chloride's inherent volatility, and you have the perfect solvent for various industrial processes.
Chemical Properties of Dichloromethane (DCM)
1.Chemical Formula: CH2C12
Viscosity: 0.43cP (20°C)
Boling point: 40°C
Melting point: - 97°C
Specific Gravity: 1.32
Density: 1.3266 g/cm3
Methylene dichloride is used as an aerosol spray propellant, a paint stripper or degreaser, and to prepare flavorings for food items and beverages. But, its one of the most popular application is decaffeinating coffee and tea.
Methylene Chloride in Tea and Caffeine Decaffeination
Methylene chloride is used to separate organic compounds like tea or caffeine from assortments of compounds. These solvent-based extractions are possible because, at 140 mg/ml, caffeine is more soluble in DCM than it is in water. Unroasted coffee beans or tea leaves will repeatedly rinse after being steamed in this solvent.
Before the caffeine is drained away due to the heat, DCM extracts the caffeine, helping produce rich and tasty coffee beans. Since DCM has a boiling point of just 40°C, it's easy to remove post-extraction. Only trivial amounts of the solvent are left on the roasted coffee after extraction. Methylene dichloride used for decaffeination is food-grade.
Both the manufacturers and various regulatory bodies assess its purity via periodic testing to ensure it's safe for the coffee beans or tea leaves to come into direct contact with the solvent. Manufacturers only leave prescribed levels of dichloromethane residue on the beans and leave to prevent any risk to the health of consumers.
Is Dichloromethane Toxic and Dangerous for Humans?
This solvent's toxicity has been questioned several times in the past. There are absolutely no grounds for fear about methylene dichloride's toxicity. A dose of DCM becomes toxic when you consume 200
When it comes to caffeine, consuming 250 mg per kilogram of your body mass is lethal. Technically, DCM is eight times less toxic than caffeine. There is no reason to think that coffee beans that have been decaffeinated with this compound are dangerous for human consumption.
The residue (solvent content) in coffee beans after processing is generally imperceptible. That's because the processing occurs at temperatures higher than 200°C (much higher than DCM's boiling point). After roasting, the solvent content is less than 0.001% in decaffeinated roasted coffee.
Plus, methylene chloride is also frequently used in the pharmaceutical industry as an excipient. In various drug manufacturing processes, this solvent is used at low concentrations to make life-saving drugs.
Advantages of Using Methylene Chloride in Tea and Caffeine Decaffeination
1.Compared to other decaffeination techniques, using methylene dichloride is actually more beneficial.
2.The compound removes irritating waxes from the coffee beans (e.g., Nβ-Alkanoyl-5-hydroxytryptamine)
3.It also removes Ochratoxin A, a dangerous carcinogenic fungal metabolite found in roasted coffee beans.
4.The solvent also eliminates many undesired flavors from the beans, such as trichloro-anisole and Geosmin.
5.Dichloromethane is a highly selective solvent, and it has a low environmental impact on manufacturing processes.
The eco-friendly nature of DCM makes it far more energy-efficient than other decaffeination and extraction techniques. That's why it's so popular in the global beverage industry.