Uso de solventes eutéticos profundos ternários na extração de cafeína a partir da borra do café

Abstract

The growing global demand for coffee results in massive production of coffee waste, primarily in the form of used coffee grounds. This residue, despite being a potentially rich source of bioactive compounds, is often discarded without efficient utilization. Among the bioactive compounds present in used coffee grounds, caffeine stands out due to its stimulating properties and its various applications in the food, pharmaceutical, and cosmetic industries. This study aimed to investigate the use of ternary deep eutectic solvents in the extraction of caffeine from coffee grounds. For this purpose, two eutectic solvents were synthesized using choline chloride as a hydrogen bond acceptor and citric acid, lactic acid, and glucose as hydrogen bond donors. A 22 experimental design was applied to evaluate the influence of temperature and time variables on the caffeine extraction process. Caffeine extraction from used coffee grounds (Coffea arabica) was performed using 0,1 g of grounds and 3 mL of solvent with 10% water addition. All extractions were conducted in a heated bath with vortex assistance. The experimental design showed that temperature had the greatest influence on caffeine extraction, resulting in higher caffeine concentrations (42,90 mg g⁻¹) in the experiment conducted at 85°C for 45 minutes. Overall, caffeine extraction with ternary Deep Eutectic Solvents proved to be an efficient alternative with good recovery rates. The deep eutectic solvent composed of choline chloride, citric acid, and lactic acid demonstrated the highest extraction capacity due to the larger number of hydroxyl sites in its chemical structure, making it an excellent caffeine extraction solvent. However, further research is needed to investigate caffeine degradation processes at higher temperatures.