An integrated process for conversion of spent coffee grounds into value-added materials.

Area of Science:

• Biorefinery and Waste Valorization
• Sustainable Chemistry
• Food Science

Background:

• Spent coffee grounds (SCG) are abundant, low-cost agro-industrial byproducts.
• SCG's complex composition presents challenges and opportunities for high-value product generation.
• Existing methods for SCG valorization are often fragmented and inefficient.

Purpose of the Study:

• To develop and evaluate a novel integrated system for converting SCG into multiple high-value products.
• To optimize environmentally friendly technologies for SCG processing.
• To assess the economic feasibility of producing co-products from SCG.

Main Methods:

• Integrated process including oil extraction, enzymatic manno-oligosaccharide (MOS) production, NaOH/H2O2 pretreatment, diterpene extraction, enzymatic hydrolysis, and fermentation.
• Utilized mannanase from Penicillium purpurogenum for MOS production.
• Employed environmentally friendly technologies throughout the process.

Main Results:

• Successfully produced coffee oil, bio-ethanol, D-mannose, manno-oligosaccharide (MOS), cafestol, and kahweol from SCG.
• Quantities obtained per kg of dry SCG: 97 mL coffee oil, 164 g D-mannose, 102 g MOS, 99 g bioethanol.
• Demonstrated efficient degradation of lignin and phenolic compounds via NaOH and H2O2 pretreatment.

Conclusions:

• The integrated biorefinery approach offers an efficient strategy for SCG valorization.
• Producing multiple high-value co-products can significantly improve biorefinery process economics.
• This method effectively reduces waste generation while creating valuable resources.