Interactions between Hazelnut (Corylus avellana L.) Protein and Phenolics and In Vitro Gastrointestinal Digestibility

Fatma Duygu Ceylan, Hilal Yılmaz, Nabil Adrar, Deniz Günal Köroğlu, Busra Gultekin Subasi, Esra Capanoglu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


In this study, we investigated the formation of protein–phenolic complexes from dephenolized hazelnut meal protein isolates (dHPI) and hazelnut skin phenolic extracts (HSE) and their effects on the bioaccessibility of both hazelnut proteins and phenolics. The dHPI–HSE complexes were of considerable size and were dependent on HSE concentration due to aggregation. Although catechin was the main component of HSE, it did not cause aggregation, except for a slight rise in particle size. According to fluorescence quenching, the hazelnut protein–phenolic extract complex had a linear Stern–Volmer plot expressing static quenching between 0–0.5 mM concentration; the interaction was mainly dependent on hydrogen bonding and van der Waals forces (ΔH < 0 and ΔS < 0), and the reaction was spontaneous (ΔG < 0). According to Fourier transform infrared (FTIR) spectroscopy results, higher phenolic extract concentration caused an increase in irregular structures in hazelnut protein, while the lowest catechin and phenolic concentration altered the regular structure. Skin extracts did not alter the digestibility of dephenolized proteins, but dephenolization reduced the degree of hydrolysis by pancreatin. The formation of the protein–phenolic complex had a beneficial effect on the bioaccessibility of hazelnut skin phenols, predominantly those on the galloylated form of the catechins, such as gallocatechin gallate and epigallocatechin gallate. Thus, the bioaccessibility and antioxidant activity analysis results showed that protein–phenolic complexes obtained from hazelnut meal and skin may promote the transition of phenolic compounds from the gastrointestinal tract without degradation.

Original languageEnglish
Article number406
Issue number12
Publication statusPublished - Dec 2022

Bibliographical note

Publisher Copyright:
© 2022 by the authors.


This research was funded by Scientific Research Projects (BAP) Unit of Istanbul Technical University, grant numbers MAB-2022-43465 and MGA-2021-43489.

FundersFunder number
Istanbul Teknik ÜniversitesiMAB-2022-43465, MGA-2021-43489


    • bioaccessibility
    • fluorescence
    • FTIR
    • hazelnut
    • protein–phenolic interaction
    • secondary structure


    Dive into the research topics of 'Interactions between Hazelnut (Corylus avellana L.) Protein and Phenolics and In Vitro Gastrointestinal Digestibility'. Together they form a unique fingerprint.

    Cite this