FENOLİK MADDE GİDERİMİ ÖN İŞLEMİNİN FINDIK KÜSPESİ PROTEİNLERİNDE YAPISAL, FONKSİYONEL VE İN VİTRO SİNDİRİLEBİLİRLİK ÖZELLİKLERİ ÜZERİNE ETKİLERİ

Abstract

Bu çalışmada fındık küspesine bir organik çözücü (etil alkol) ile uygulanan fenolik madde giderimi ön işleminin, alkali ekstraksiyon-izoelektrik noktada çöktürme yöntemi ile elde edilen proteinlerin yapısal, fonksiyonel ve sindirilebilirlik özellikleri üzerindeki etkilerini zamana bağlı olarak incelenmiştir. Elde edilen bulgulara göre, 10 saatlik fenolik madde giderimi sonucunda toplam fenolik madde miktarında %74’lük bir azalma sağlanırken, protein saflığı %85.53'ten %97.22'ye yükselmiştir. Proteinlerin beyazlık değerlerinde belirgin bir artış kaydedilmiştir. Yapısal analizler, fenoliklerin uzaklaştırılmasının alfa heliks oranını düşürüp beta tabaka yapılarını artırarak protein konformasyonunu değiştirdiğini, 2 saatlik ön işlemin protein yapısını açarak yüzey hidrofobitesini maksimuma çıkardığını ancak daha uzun sürelerin proteinlerin yeniden katlanmasına veya agregasyonuna yol açtığını göstermiştir. Fenolik madde giderimiyle protein çözünürlüğü (%43.97-%50.24) ve su tutma kapasitesi (2.47-2.68 g/g) 4. saatte en yüksek seviyelerine ulaşırken, köpük oluşturma kapasitesi (%14.44’ten %78.89’a; 8. saat) ve yağ tutma kapasitesi (2.01-2.21 g/g; 10. saat) artış göstermiştir. Emülsiyon aktivite indeksi (28.53-22.20 m2/g) düşüş gösterse de emülsiyon stabilitesi 27.49’dan 46.98 dakikaya yükselmiştir. In vitro sindirilebilirlik analizlerinde ise kontrol grubuna kıyasla fenolik madde giderimi arttıkça protein sindirilebilirliği oranında bir azalma gözlenmiştir. Sonuç olarak, fenolik madde giderimi fındık proteini kalitesini renk ve fonksiyonellik açısından geliştirirken, besinsel verimlilik ile teknolojik performans arasında optimum bir denge kurulması için ön işlem süresinin önemli bir parametre olduğu ortaya konmuştur.

Keywords

• Fenolik maddeler
• fındık
• fonksiyonel özellikler
• protein
• sindirilebilirlik

EFFECTS OF PHENOLIC REMOVAL PRETREATMENT ON THE STRUCTURAL, FUNCTIONAL, AND IN VITRO DIGESTIBILITY PROPERTIES OF HAZELNUT MEAL PROTEINS

Abstract

This study investigated the time-dependent effects of the phenolic removal pretreatment using an organic solvent (ethanol) on the structural, functional, and digestibility properties of proteins isolated from hazelnut meal using the alkaline extraction-isoelectric precipitation method. According to the findings, a 10-hour phenolic removal pretreatment resulted in a 74% reduction in total phenolic content, while protein purity increased from 85.53% to 97.22%. A significant increase in the whiteness index of the proteins was also recorded. Structural analyses revealed that the removal of phenolics altered the protein conformation by decreasing the alpha-helix ratio and increasing beta-sheet structures; a 2-hour pretreatment opened the protein structure, maximizing surface hydrophobicity, whereas longer durations led to protein refolding or aggregation. With phenolic removal pretreatment, protein solubility (43.97%-50.24%) and water holding capacity (2.47-2.68 g/g) reached their peak levels at 4 h, while foaming capacity (from 14.44% to 78.89% at 8 h) and oil holding capacity (2.01-2.21 g/g at 10 h) showed an increase. Although the emulsion activity index decreased (28.53-22.20 m2/g), the emulsion stability increased from 27.49 to 46.98 minutes. In vitro digestibility analyses showed a decrease in digestibility rates as phenolic removal increased compared to the control group. In conclusion, while phenolic removal improves hazelnut protein quality in terms of color and functionality, the pretreatment duration proved to be a critical parameter for establishing an optimum balance between nutritional efficiency and technological performance.

Keywords

• Phenolic compounds
• hazelnut
• functional properties
• protein
• digestibility

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