Chemical and Bioactive Screening of Green Polyphenol-Rich Extracts from Chestnut By-Products: An Approach to Guide the Sustainable Production of High-Added Value Ingredients

What if the spiky shells and leaves you throw away could become natural food preservatives? A new study shows chestnut by-products are packed with polyphenols that fight bacteria and oxidation.

Chestnut farming leaves behind a mountain of burs, shells, and leaves—often treated as waste. But these leftovers are far from useless. Scientists have discovered that green, water-based extracts from these by-products are treasure troves of bioactive polyphenols, with the power to preserve food naturally.

The team compared three extraction methods—simple maceration, ultrasound, and microwave—using water or hydroethanolic solvents. Leaf extracts from maceration and ultrasound came out on top, with phenolic concentrations up to 70.92 mg per gram of dry extract. For burs and shells, ultrasound with hydroethanolic solvent worked best, yielding 36.87 mg and 23.03 mg per gram, respectively.

These extracts weren't just rich in compounds like bis-HHDP-glucose and gallic acid—they were also potent antioxidants. Bur extracts excelled in TBARS assays, while shell extracts shined in DPPH and reducing power tests. Most strikingly, an aqueous microwave extract from burs killed three food-borne bacteria—E. cloacae, P. aeruginosa, and S. aureus—at just 5 mg/mL.

The study proves that chestnut waste can be transformed into high-value natural additives. The choice of extraction method and solvent matters greatly, but the potential is clear: a sustainable path from agricultural waste to food safety.

Key Points

• Leaf extracts hit 70.92 mg/g phenolics with maceration or ultrasound.
• Aqueous bur extract kills three food-borne bacteria at 5 mg/mL.
• Extraction method and solvent drastically alter bioactivity.