Upcycling Coffee By-Products Into Functional Ingredients: A Review on Sustainable Processing, Health Benefits, and Food Applications

Did you know that turning apples into juice or cider leaves behind a mountain of pomace—25–30% of the fruit's fresh weight—packed with hidden treasures like fiber, vitamins, and polyphenols?

When apples are crushed for juice or cider, the leftover pomace is often discarded, yet it holds a wealth of health-promoting compounds. To unlock this potential, researchers compared two drying techniques—hot-air convection and infrared—to see which better preserves the polyphenols while extending shelf life. Both methods significantly altered color and polyphenol content with high antioxidant activity, but higher temperatures proved beneficial by partially inactivating browning enzymes. Infrared drying emerged as the winner, requiring less time and energy than convection drying.

But drying is just the first step. The team also explored how to extract these valuable compounds using ultrasound-assisted extraction with a natural deep eutectic solvent (NaDES) made from choline chloride and glycerol. This eco-friendly solvent outperformed conventional solvents and other NaDES mixtures, recovering more phenolic compounds with high antioxidant activity. By optimizing the extraction conditions, they achieved an extract rich in flavan-3-ols like catechin and epigallocatechin, along with phenolic acids such as chlorogenic acid.

These findings highlight apple pomace as a promising source of bioactive ingredients and position polyol-based NaDES as a sustainable, efficient alternative for their recovery. The study not only offers a greener path for food processing but also turns waste into a functional resource—a win for both health and the planet.

Key Points

• Apple pomace is 25–30% of fresh fruit mass, rich in fiber, vitamins, polyphenols.
• Infrared drying beats convection: faster, less energy, preserves polyphenols.
• Choline chloride-glycerol NaDES outperforms conventional solvents in extraction.