Cellulose-Rich Polysaccharide Extracts with Gel-Forming Potential and Improved Antioxidant Properties from Stem (Vitis vinifera L.) By-Products: Ultrasound-Assisted Aqueous Extraction and Characterization

Wine waste is about to become a treasure trove: ultrasound can unlock antioxidant-rich, gel-forming polysaccharides from grape stems in minutes, not hours.

Every year, wineries discard tons of grape stems, a by-product that most consider worthless. But hidden inside these woody stems are valuable compounds: phenolic antioxidants and cellulose-rich polysaccharides that can form gels. Now, researchers have found a faster, greener way to extract them all at once, using nothing but water and ultrasound.

The team tested ultrasound-assisted aqueous extraction (UAE) at three temperatures (10, 20, 50 °C) and three power levels (120, 206, 337 W/L), comparing it to conventional stirring. The results were striking: UAE dramatically sped up extraction of phenolics and antioxidants, boosting total phenolic yield by up to 3.1-fold at 20 °C. Even better, using 337 W/L at 20 °C matched the antioxidant levels of conventional extraction at 50 °C, meaning they could achieve high efficiency at lower, compound-friendly temperatures.

The extracts were naturally rich in cellulose (glucose ~49–52 mol%), with pectins and hemicelluloses forming a composite matrix that can gel. While total polysaccharide yield was highest at 10 °C, the main benefit of UAE was speed and structural tweaking, not bulk yield. It slashed extraction times by 3 to over 6 times for equivalent bioactivity.

This one-step, water-based process aligns perfectly with green chemistry, turning an underused residue into a multifunctional extract for cellulose-rich hydrogels. The future of food and pharma could be rooted in wine waste.

Key Points

• UAE boosts phenolic yield up to 3.1-fold.
• 337 W/L at 20°C matches 50°C conventional extraction.
• Extracts are cellulose-rich (glucose ~49–52 mol%).