Decaffeination processes fall into two categories: solvent and non-solvent. As our current decaf is the former, solvent-based decaffeination will be the focus of this post -- specifically, sugarcane-derived Natural Ethyl Acetate direct decaffeination (say that five times fast)!
Solvent-based decaffeination can be performed directly or indirectly. In the former, solvent is applied to green coffee and washed away once decaffeination is complete. In the latter, a hot water bath is used to extract not only caffeine, but other flavor- and aroma-producing compounds. Solvent is then applied to the solution, binding to caffeine. Finally, heat is applied to remove the caffeine-laden solvent and the remaining solution is infused into the green coffee (Coffee Confidential).
Ethyl Acetate is a naturally-occurring compound found in cereal crops, alcoholic beverages, and more. Among other things, it is used as a “solvent in the [manufacturing] of modified hop extract and decaffeinated tea or coffee” (PubChem). An FDA-approved process, sugarcane-derived Natural Ethyl Acetate direct decaffeination maintains wonderfully the flavors and aromas of coffee while safely and effectively removing caffeine.
To begin, green coffee is bathed in steam, removing the silver skin of the seeds. A hot water bath follows, further swelling and softening the coffee. In adding moisture, the coffee becomes more receptive to solvents and the hydrolysis of caffeine begins.
Hydrolysis: “a chemical reaction in which water is used to break down a compound; this is achieved by breaking a covalent bond in the compound by inserting a water molecule across the bond” (Northwestern University). In the case of coffee, this bond is between caffeine and salts of chlorogenic acid (InterAmerican Coffee).
Now receptive to the Ethyl Acetate, multiple circulations of the solvent are performed until 97% of caffeine is stripped from the seeds. After, the coffee is again bathed in steam, this time removing the Ethyl Acetate. What little solvent remains (less than 5 parts per million) is removed in roasting (InterAmerican Coffee).
Finally, the coffee is dried to remove added moisture, returning the green coffee to, approximately, its original moisture content (10% to 12%) (InterAmerican Coffee). The end result: decaf that tastes like true specialty coffee!
Next week: non-solvent based processes!