Identification of polyphenol composition in grape (Vitis vinifera cv. Bidaneh Sefid) stem using green extraction methods and LC–MS/MS analysis

Grape stems, the winemaking industry's overlooked waste, hide a treasure trove of polyphenols—and a new study reveals the greenest way to unlock them.

Every year, tons of grape stems end up as compost or animal feed. Yet these discarded by-products are packed with bioactive compounds—especially polyphenols—that could fuel pharmaceuticals, nutraceuticals, and cosmetics. A recent study turned to an Iranian grape variety, Bidaneh Sefid, to explore how eco-friendly extraction methods can tap into this potential.

The researchers tested four extraction methods, all using water or polyethylene glycol (PEG) as green solvents. They combined these with maceration, microwave, ultrasound, and reduced-pressure techniques. Then, using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–ESI-MS/MS), they identified a total of 29 polyphenols, including phenolic acids, flavonoids, proanthocyanidins, and stilbenes.

The results were clear: methods 1 (water + microwave + ultrasound + atmospheric pressure) and 2 (water + microwave + ultrasound + reduced pressure) worked best. These techniques efficiently extracted both hydrophobic and hydrophilic compounds, proving that green chemistry can rival traditional methods.

This isn't just about waste management—it's about turning a problem into a resource. By optimizing these green extraction methods, we could create value-added products from grape stems while reducing environmental impact. The study underscores a simple truth: sometimes the best solutions are hiding in what we throw away.

Key Points

• 29 polyphenols found in grape stems via green extraction.
• Water and PEG as solvents, with microwave and ultrasound.
• Methods 1 and 2 most effective; green chemistry wins.