Caffeine extraction from spent coffee grounds

Abstract

Caffeine(3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) is a widespread naturally occurring xanthine derivative found in a variety of plants but commonly found in coffee beans and tea leaves. Caffeine containing products have been consumed for hundreds of years for their taste, aroma, and Central Nervous System (CNS) stimulating properties. This study aimed at extracting and optimizing an extraction process of caffeine from spent coffee grounds (coffee waste). This was done through investigating the efficiency of various solvents for extracting caffeine from spent coffee grounds using liquid -liquid and solid liquid extraction at different extraction temperatures. Five solvents were evaluated i.e. chloroform, dichloromethane, ethanol, acetone, and ethyl acetate. The experiment involved heating the obtained spent coffee grounds sample in the oven to obtain the moisture content. Each solvent was used to extract caffeine from the spent coffee grounds samples at different extraction temperatures and the amount of extracted caffeine was determined. The results revealed that dichloromethane was the most efficient solvent for caffeine extraction from spent coffee grounds with an amount of 0.2170g of caffeine per 50g of spent coffee grounds. Other solvents showed varying degrees of efficiency in the order chloroform (0.1301g of caffeine per 50g of spent coffee grounds), ethyl acetate (0.0705g of caffeine per 50g of spent coffee grounds), ethanol (4.5284g of extract per 50g of spent coffee grounds) and finally acetone (4.2908g of extract per 50g of spent coffee grounds). This study identified dichloromethane as the most suitable solvent for extracting caffeine from spent coffee grounds (coffee waste) using liquid –liquid extraction. Further research could explore optimizing extraction parameters for this solvent or investigating the feasibility of using greener alternatives.