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Journals / Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi / 2026 / Cilt: 17

Valorization of spent coffee grounds using circulating ohmic heating and batch ultrasound-assisted extraction: Recovery of phenolic compounds and assessment of antioxidant activity potential

Kapalı devre sirkülasyonlu ohmik ısıtma ve kesikli ultrason destekli ekstraksiyon kullanılarak kahve atıklarının değerlendirilmesi: Fenolik bileşiklerin geri kazanımı ve antioksidan aktivite potansiyelinin incelenmesi

Erkan Karacabey(SÜLEYMAN DEMİREL ÜNİVERSİTESİ, MÜHENDİSLİK VE DOĞA BİLİMLERİ FAKÜLTESİ, GIDA MÜHENDİSLİĞİ BÖLÜMÜ)0000-0002-0428-2039
Yelizcan Turgut(SÜLEYMAN DEMİREL ÜNİVERSİTESİ, MÜHENDİSLİK VE DOĞA BİLİMLERİ FAKÜLTESİ, GIDA MÜHENDİSLİĞİ BÖLÜMÜ)0000-0002-5801-5550
Ayse Özçelik(SÜLEYMAN DEMİREL ÜNİVERSİTESİ, MÜHENDİSLİK VE DOĞA BİLİMLERİ FAKÜLTESİ, GIDA MÜHENDİSLİĞİ BÖLÜMÜ)0000-0003-0867-0466
Sebahattin Serhat Turgut(SÜLEYMAN DEMİREL ÜNİVERSİTESİ, MÜHENDİSLİK VE DOĞA BİLİMLERİ FAKÜLTESİ, GIDA MÜHENDİSLİĞİ BÖLÜMÜ)0000-0002-9968-4750
Pages
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Publication Date
2026-06-04
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

Overall, ODE and UDE proved to be effective approaches for converting coffee waste into value-added natural antioxidant sources.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:Coffee is one of the most widely consumed beverages worldwide and a major traded commodity.
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Key Findings & Data:All extractions were conducted at 60°C for 30 min using a 50% (v/v) methanol solution and a solid-to-liquid ratio of 1:20.
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Conclusion & Impact:Overall, ODE and UDE proved to be effective approaches for converting coffee waste into value-added natural antioxidant sources.
🔬Design:Araştırma Makalesi
📍Scope:Comprehensive Sample
⚙️Variables:Fenolik madde · Antioksidan kapasite · Joule ısıtma

Abstract

Coffee is one of the most widely consumed beverages worldwide and a major traded commodity. The increasing consumption of coffee has resulted in the generation of large amounts of waste rich in bioactive compounds. This study investigates the valorization of coffee waste for phenolic compound recovery using ohmic heating-assisted extraction (ODE) and ultrasound-assisted extraction (UDE), with conventional solid–liquid extraction (KSE) as a reference. Total phenolic content (TF) and antioxidant activities (DPPH and ABTS) were evaluated for extracts obtained under controlled conditions. All extractions were conducted at 60°C for 30 min using a 50% (v/v) methanol solution and a solid-to-liquid ratio of 1:20. ODE was performed by applying a potential difference of 200 V, and solvent circulation (5 L/min) was used to assess convective mass transfer effects. A cartridge system was developed for closed-loop operation and its impact on extraction efficiency was examined. The highest TF recovery was achieved using methanol-based ODE, while methanol-based UDE exhibited the highest ABTS activity. Solvent circulation enhanced extraction efficiency, whereas cartridge use limited mass transfer. Overall, ODE and UDE proved to be effective approaches for converting coffee waste into value-added natural antioxidant sources.

Özet

Kahve, dünya genelinde en yaygın tüketilen içeceklerden biri olmasının yanı sıra önemli bir ticari emtiadır. Artan kahve tüketimi, üretim sürecinde biyoaktif bileşikler açısından zengin büyük miktarda atığın oluşmasına neden olmaktadır. Bu çalışmada, kahve atıklarının fenolik bileşiklerin geri kazanımı amacıyla ohmik ısıtma destekli ekstraksiyon (ODE) ve ultrason destekli ekstraksiyon (UDE) yöntemleri kullanılarak değerlendirilmesi incelenmiş; karşılaştırma amacıyla geleneksel katı–sıvı ekstraksiyonu (KSE) referans olarak alınmıştır. Kontrollü koşullar altında elde edilen ekstraktlarda toplam fenolik madde (TF) içeriği ile DPPH ve ABTS antioksidan aktiviteleri belirlenmiştir. Tüm ekstraksiyonlar, %50 (v/v) metanol çözeltisi kullanılarak 60°C’de 30 dakika süreyle ve 1:20 katı:sıvı oranında gerçekleştirilmiştir. ODE uygulamalarında 200 V potansiyel fark uygulanmış, konvektif kütle aktarımının etkisini değerlendirmek amacıyla çözücü 5 L/dk debide sirküle edilmiştir. Kapalı devre çalışma için geliştirilen kartuş sisteminin ekstraksiyon verimliliğine etkisi de incelenmiştir. En yüksek TF geri kazanımı metanol kullanılan ODE ile elde edilirken, en yüksek ABTS aktivitesi metanol bazlı UDE’de gözlenmiştir. Çözücü sirkülasyonu ekstraksiyon verimini artırmış, kartuş kullanımı ise kütle aktarımını sınırlandırmıştır. Sonuçlar, ODE ve UDE yöntemlerinin kahve atıklarının katma değeri yüksek doğal antioksidan kaynaklarına dönüştürülmesinde etkili yaklaşımlar olduğunu göstermektedir.

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Cite This Article

Karacabey, E., Turgut, Y., Özçelik, A., Turgut, S. S. (2026). Valorization of spent coffee grounds using circulating ohmic heating and batch ultrasound-assisted extraction: Recovery of phenolic compounds and assessment of antioxidant activity potential. Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi, Cilt: 17. https://doi.org/10.28948/ngumuh.1873899

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