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Journals / Selcuk Journal of Agriculture and Food Sciences / 2026 / Cilt: 40 Sayı: 1

Kefir Fermentation-Induced Changes in Bioactive Compounds and Antioxidant Activity of Defatted Hazelnut Protein Isolate

Kefir Fermantasyonunun Yağsız Fındık Protein İzolatının Biyoaktif Bileşiklerinde ve Antioksidan Aktivitesinde Meydana Getirdiği Değişimler

Ertan Ermiş(İstanbul Sabahattin Zaim Üniversitesi)0000-0002-1461-7357
Senanur İyibaş(İSTANBUL SABAHATTİN ZAİM ÜNİVERSİTESİ)0000-0000-0000-0000
İrem Küçük(İSTANBUL SABAHATTİN ZAİM ÜNİVERSİTESİ)0000-0000-0000-0001
Hilal Albayraktar(İSTANBUL SABAHATTİN ZAİM ÜNİVERSİTESİ)0000-0000-0000-0002
Pages
190–201
Publication Date
2026-04-28
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AI Summary & Key Takeaways

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

Overall, kefir fermentation of hazelnut protein isolates improved antioxidant and functional properties, highlighting their potential application in functional foods.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:This study investigated the enhancement of functional properties of proteins extracted from defatted hazelnut pulp through kefir fermentation.
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Key Findings & Data:Fermentation significantly altered the composition and functionality of hazelnut protein isolates.
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Conclusion & Impact:Overall, kefir fermentation of hazelnut protein isolates improved antioxidant and functional properties, highlighting their potential application in functional foods.
🔬Design:Araştırma Makalesi
📍Scope:Comprehensive Sample
⚙️Variables:Fındık Posası · Protein Ekstraksiyonu · Fermentasyon

Abstract

This study investigated the enhancement of functional properties of proteins extracted from defatted hazelnut pulp through kefir fermentation. Analyses included pH, titratable acidity, protein content, reducing sugars, phenolic and flavonoid contents, antioxidant activity, and antimicrobial effects. Fermentation significantly altered the composition and functionality of hazelnut protein isolates. Fermentation caused an apparent 88% increase in measured water-soluble protein content in the liquid phase, while titratable acidity rose more than fourfold, accompanied by a pH decline. Total phenolic and flavonoid contents increased by 53% and 32%, respectively, enhancing antioxidant activity, which nearly doubled by the third day. The reducing sugar content also increased, reaching a peak on the second day. Despite these improvements, fermented samples showed no marked antimicrobial effects against E. coli and S. aureus. Overall, kefir fermentation of hazelnut protein isolates improved antioxidant and functional properties, highlighting their potential application in functional foods. Further studies with defined microbial strains and extended fermentation times are recommended to optimize bioactive compound production.

Özet

Bu çalışma, yağsızlaştırılmış fındık posasından elde edilen proteinlerin fonksiyonel özelliklerinin kefir fermantasyonu yoluyla iyileştirilmesini araştırmıştır. Analizler pH, titre edilebilir asitlik, protein içeriği, indirgeyici şekerler, fenolik ve flavonoid içerikleri, antioksidan aktivite ve antimikrobiyal etkileri içermiştir. Fermantasyon, fındık protein izolatlarının bileşimini ve işlevselliğini önemli ölçüde değiştirmiştir. Fermantasyon, sıvı fazda ölçülen suda çözünür protein içeriğinde %88'lik bir artışa neden olurken, titre edilebilir asitlik dört kattan fazla artmış ve pH'da düşüş gözlenmiştir. Toplam fenolik ve flavonoid içerikleri sırasıyla %53 ve %32 artarak antioksidan aktiviteyi artırmış ve üçüncü günde neredeyse iki katına çıkmıştır. İndirgeyici şeker içeriği de artmış ve ikinci günde zirveye ulaşmıştır. Bu iyileşmelere rağmen, fermente edilmiş örnekler E. coli ve S. aureus'a karşı belirgin bir antimikrobiyal etki göstermemiştir. Genel olarak, fındık protein izolatlarının kefir fermantasyonu, antioksidan ve fonksiyonel özellikleri iyileştirerek fonksiyonel gıdalarda potansiyel uygulamalarını vurgulamıştır. Biyoaktif bileşik üretimini optimize etmek için tanımlanmış mikrobiyal suşlarla ve daha uzun fermantasyon süreleriyle yapılacak ileri çalışmalar önerilmektedir.

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Cite This Article

Ermiş, E., İyibaş, S., Küçük, İ., Albayraktar, H. (2026). Kefir Fermentation-Induced Changes in Bioactive Compounds and Antioxidant Activity of Defatted Hazelnut Protein Isolate. Selcuk Journal of Agriculture and Food Sciences, Cilt: 40 Sayı: 1, 190–201. https://doi.org/10.15316/selcukjafsci.1782041

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