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

Abstract

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.

Keywords

• Fındık Posası
• Protein Ekstraksiyonu
• Fermentasyon
• Fonksiyonel Gıdalar

Project Number

1919B012210203

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

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.

Keywords

• Hazelnut Meal
• Protein Extraction
• Fermentation
• Functional Foods
• Antioxidant Activity

Supporting Institution

The Scientific and Technological Research Council of Turkey

Project Number

1919B012210203

Ethical Statement

This article does not involve studies with human participants or animals performed by any of the authors. All experimental procedures were conducted in compliance with institutional, national, and international guidelines for research integrity and safety. No ethical approval was required for this study.

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