Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics
Walnut (<i>Juglans regia</i> 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...
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MDPI AG
2025-06-01
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| Series: | Foods |
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| Online Access: | https://www.mdpi.com/2304-8158/14/13/2245 |
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| author | Busra Acoglu Celik Muhammed Alpgiray Celik Laura Jūrienė Jovita Jovaišaitė Rita Kazernavičiūtė Erturk Bekar Perihan Yolci Omeroglu Petras Rimantas Venskutonis Senem Kamiloglu |
| author_facet | Busra Acoglu Celik Muhammed Alpgiray Celik Laura Jūrienė Jovita Jovaišaitė Rita Kazernavičiūtė Erturk Bekar Perihan Yolci Omeroglu Petras Rimantas Venskutonis Senem Kamiloglu |
| author_sort | Busra Acoglu Celik |
| collection | DOAJ |
| description | Walnut (<i>Juglans regia</i> 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<sup>•+</sup>, DPPH•), 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<sup>®</sup> L at pH 3.5 and 45 °C. Under the same extraction conditions, UAE alone yielded the second highest TPC (4129 mg GAE/100 g dw). The highest ABTS<sup>•+</sup> scavenging activity (14,478 mg TE/100 g dw) and enhanced DPPH• 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. |
| format | Article |
| id | doaj-art-e0fe320c90614b7cb07815e3889616c0 |
| institution | Kabale University |
| issn | 2304-8158 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Foods |
| spelling | doaj-art-e0fe320c90614b7cb07815e3889616c02025-08-20T03:50:20ZengMDPI AGFoods2304-81582025-06-011413224510.3390/foods14132245Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with ChemometricsBusra Acoglu Celik0Muhammed Alpgiray Celik1Laura Jūrienė2Jovita Jovaišaitė3Rita Kazernavičiūtė4Erturk Bekar5Perihan Yolci Omeroglu6Petras Rimantas Venskutonis7Senem Kamiloglu8Department of Food Engineering, Faculty of Agriculture, Bursa Uludag University, Gorukle Campus, 16059 Bursa, TürkiyeDepartment of Food Hygiene and Technology, Faculty of Veterinary Medicine, Bursa Uludag University, Gorukle Campus, 16059 Bursa, TürkiyeDepartment of Food Science and Technology, Kaunas University of Technology, Radvilėnų pl. 19, LT-50254 Kaunas, LithuaniaDepartment of Food Science and Technology, Kaunas University of Technology, Radvilėnų pl. 19, LT-50254 Kaunas, LithuaniaDepartment of Food Science and Technology, Kaunas University of Technology, Radvilėnų pl. 19, LT-50254 Kaunas, LithuaniaDepartment of Food Engineering, Faculty of Agriculture, Bursa Uludag University, Gorukle Campus, 16059 Bursa, TürkiyeDepartment of Food Engineering, Faculty of Agriculture, Bursa Uludag University, Gorukle Campus, 16059 Bursa, TürkiyeDepartment of Food Science and Technology, Kaunas University of Technology, Radvilėnų pl. 19, LT-50254 Kaunas, LithuaniaDepartment of Food Engineering, Faculty of Agriculture, Bursa Uludag University, Gorukle Campus, 16059 Bursa, TürkiyeWalnut (<i>Juglans regia</i> 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<sup>•+</sup>, DPPH•), 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<sup>®</sup> L at pH 3.5 and 45 °C. Under the same extraction conditions, UAE alone yielded the second highest TPC (4129 mg GAE/100 g dw). The highest ABTS<sup>•+</sup> scavenging activity (14,478 mg TE/100 g dw) and enhanced DPPH• 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.https://www.mdpi.com/2304-8158/14/13/2245<i>Juglans regia</i> L. shellgreen extractioncombined extractionphenolic compoundsantioxidant capacityprincipal component analysis |
| spellingShingle | Busra Acoglu Celik Muhammed Alpgiray Celik Laura Jūrienė Jovita Jovaišaitė Rita Kazernavičiūtė Erturk Bekar Perihan Yolci Omeroglu Petras Rimantas Venskutonis Senem Kamiloglu Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics Foods <i>Juglans regia</i> L. shell green extraction combined extraction phenolic compounds antioxidant capacity principal component analysis |
| title | Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics |
| title_full | Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics |
| title_fullStr | Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics |
| title_full_unstemmed | Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics |
| title_short | Biorefining of Walnut Shells into Polyphenol-Rich Extracts Using Ultrasound-Assisted, Enzyme-Assisted, and Pressurized Liquid Extraction Coupled with Chemometrics |
| title_sort | biorefining of walnut shells into polyphenol rich extracts using ultrasound assisted enzyme assisted and pressurized liquid extraction coupled with chemometrics |
| topic | <i>Juglans regia</i> L. shell green extraction combined extraction phenolic compounds antioxidant capacity principal component analysis |
| url | https://www.mdpi.com/2304-8158/14/13/2245 |
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