Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics

Acoglu Celik B., Celik M. A., Jūrienė L., Jovaišaitė J., Kazernavičiūtė R., BEKAR E., ...Daha Fazla

FOODS, cilt.14, sa.13, 2025 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 14 Sayı: 13
  • Basım Tarihi: 2025
  • Doi Numarası: 10.3390/foods14132245
  • Dergi Adı: FOODS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Agricultural & Environmental Science Database, CAB Abstracts, Food Science & Technology Abstracts, Veterinary Science Database, Directory of Open Access Journals
  • Anahtar Kelimeler: antioxidant capacity, combined extraction, green extraction, Juglans regia L. shell, phenolic compounds, principal component analysis
  • Bursa Uludağ Üniversitesi Adresli: Evet

Özet

Walnut (Juglans regia L.) shells are valuable agro-industrial by-products rich in polyphenols. This study investigated traditional (maceration) and advanced extraction techniques-ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), pressurized liquid extraction (PLE), and combined ultrasound-enzyme extraction (US-EAE)-to recover bioactive compounds from walnut shells. Extraction efficiency, total phenolic content (TPC), antioxidant capacity (ABTS center dot+, DPPH center dot), and polyphenol composition were evaluated. UPLC-ESI-MS/MS identified key polyphenols including ellagic acid, 4-hydroxybenzoic acid, vanillin, taxifolin, and quercitrin. The highest TPC (5625 mg GAE/100 g dw) was found in extracts subjected to US-EAE, in which ultrasound pretreatment (200 W, 10 min) was followed by enzymatic extraction using 0.06 mL/g Viscozyme (R) L at pH 3.5 and 45 degrees C. Under the same extraction conditions, UAE alone yielded the second highest TPC (4129 mg GAE/100 g dw). The highest ABTS center dot+ scavenging activity (14,478 mg TE/100 g dw) and enhanced DPPH center dot activity (45.38 mg TE/100 g dw) were also observed in US-EAE extracts. Chemometric techniques (PCA and HCA) revealed meaningful clustering and variation patterns among methods. These findings highlight the potential of walnut shells as a sustainable source of polyphenols and demonstrate the effectiveness of innovative extraction technologies in maximizing bioactive compound recovery for potential functional applications.