Green valorization of coffee industry residues: Emerging innovations and their role in sustainable food and feed applications

Every cup of coffee leaves behind a mountain of waste—but that waste is secretly a treasure trove of bioactive compounds, fiber, and protein. What if we could turn coffee's leftovers into food and feed?

The coffee industry discards vast amounts of pulp, husk, silverskin, and spent coffee grounds—by-products often treated as trash. Yet these residues are packed with valuable bioactive compounds, dietary fiber, proteins, and lipids, making them prime candidates for sustainable valorization.

This review synthesizes the latest advances in green valorization, focusing on food and feed applications. It dives into the compositional makeup of coffee by-products and highlights emerging transformation technologies: fermentation to produce organic acids, enzymes, and single-cell proteins; green extraction methods like supercritical CO₂, microwave, and ultrasound to recover antioxidants, caffeine, and phenolics; and chemical conversions such as hydrolysis and Maillard reactions to create fermentable sugars, prebiotics, and flavor compounds.

Novel approaches like solid-state fermentation and encapsulation are also explored to boost the functional value of these residues. Beyond waste reduction, valorizing coffee by-products supports environmental sustainability while opening new avenues for circular bioeconomy.

Key Points

• Coffee by-products are rich in bioactive compounds, fiber, protein, and lipids.
• Green technologies: fermentation, supercritical CO₂, microwave, ultrasound extraction.
• Valorization supports sustainability and circular economy in food and feed.