Valorisation of coffee husk for functional arabinogalactans: A sustainable value-added ingredient

Area of Science:

• Food Chemistry
• Biopolymer Science
• Sustainable Resource Utilization

Background:

• Coffee husks are abundant agricultural byproducts, comprising approximately 18% of coffee cherry dry weight.
• Despite their high polysaccharide content (around 58%), their physicochemical properties, structure, and bioactivities are underexplored.
• Valorization of coffee husks is crucial for sustainable waste management and resource utilization in the food industry.

Purpose of the Study:

• To investigate the efficient extraction and characterization of polysaccharides from coffee husks.
• To evaluate the physicochemical properties and antioxidant activities of the extracted polysaccharides.
• To explore the potential of coffee husk polysaccharides as functional food ingredients.

Main Methods:

• Alkali extraction using 0.4 M NaOH at a 1:10 substrate-to-solvent ratio, 55°C for 6 hours.
• Characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), proton nuclear magnetic resonance (¹H NMR), and differential scanning calorimetry (DSC).
• Assessment of physicochemical properties including water holding, oil holding, and swelling capacities.

Main Results:

• An arabinogalactan-rich polysaccharide was extracted, constituting 12.83% of the husk, with 84.49% total carbohydrates.
• The polysaccharide was predominantly composed of galactose (44.77%) and arabinose (33.57%) with a molecular weight of 121 kDa.
• Demonstrated significant water holding (23.8 g/g), oil holding (13.2 g/g), swelling capacities (2.25 mL/g), and strong antioxidant activity.

Conclusions:

• Alkali extraction provides an efficient method for obtaining valuable polysaccharides from coffee husks.
• The extracted arabinogalactan-rich polysaccharide possesses favorable physicochemical properties and antioxidant capacity.
• Coffee husks represent a sustainable and promising source for functional food ingredients.