Deep eutectic solvent-based valorization of spent coffee grounds.

Area of Science:

• Green Chemistry
• Biotechnology
• Food Science

Background:

• Spent coffee grounds (SCGs) are a rich source of bioactive compounds like chlorogenic acids and flavonoids.
• Valorization of SCGs offers a sustainable approach to waste management and resource recovery.
• Deep eutectic solvents (DESs) are emerging as environmentally friendly alternatives to traditional organic solvents.

Purpose of the Study:

• To develop an eco-friendly and efficient method for extracting bioactive compounds from SCGs.
• To investigate the efficacy of choline chloride-based DESs combined with ultrasound-assisted extraction.
• To optimize extraction conditions for maximizing total phenolic content (TPC) and antioxidant activity.

Main Methods:

• Screening of various choline chloride-based DESs for extraction efficiency.
• Optimization of extraction parameters using fractional factorial design and central composite design.
• Ultrasound-assisted extraction (UAE) was employed for enhanced mass transfer.
• Quantification of TPC, total flavonoid content, total chlorogenic acids, and antioxidant activity.

Main Results:

• A binary DES, HC-6 (1,6-hexanediol:choline chloride, 7:1 molar ratio), demonstrated the highest extraction efficiency.
• Optimized UAE with HC-6 significantly enhanced TPC and antioxidant activity of SCG extracts.
• Phenolic compounds were recovered with high yields (>90%) using adsorption chromatography.

Conclusions:

• The proposed DES-assisted UAE method is effective for valorizing SCGs.
• This approach offers a sustainable and efficient route for obtaining valuable bioactive compounds.
• High recovery rates of phenolic compounds facilitate their further application.