Please use this identifier to cite or link to this item: http://dx.doi.org/10.25673/116534
Title: Formation of cysteine adducts with chlorogenic acid in coffee beans
Author(s): Tchewonpi Sagu, Sorel
Ulbrich, Nina
Morche, Johanna Rebekka
Nichani, Kapil
Özpinar, Haydar
Schwarz, Steffen
Henze, Andreas
Rohn, SaschaLook up in the Integrated Authority File of the German National Library
Rawel, Harshadrai ManilalLook up in the Integrated Authority File of the German National Library
Issue Date: 2024
Type: Article
Language: English
Abstract: The post-harvest processing of coffee beans leads to a wide range of reactions involving proteins. The formation of crosslinks between proteins and phenolic compounds present in high concentrations of coffee beans represents one of the most challenging and still not fully characterized reactions. The aim of this work was to assess the presence of products from such reactions in coffee samples, focusing on the adducts between cysteine and chlorogenic acids (CQAs). For this purpose, 19 green and 15 roasted coffee samples of the Coffea arabica, Coffea canephora, and Coffea liberica varieties were selected for this study and basically characterized. Then, targeted liquid chromatography mass spectrometry (LC-MS/MS) methods were developed to assess the formation of adducts between CQA and cysteine, glutathione, and N-acetylcysteine as the amino acid and peptide models, and quantified such adducts in coffee samples. The results of the characterization showed a heterogeneous distribution of the protein content (8.7–14.6%), caffeine (0.57–2.62 g/100 g), and antioxidant capacity (2–4.5 g ascorbic acid/100 g) in Arabica, Canephora, and Liberica samples. Glutamic acid, arginine, and proline were found to be the major amino acids, while 5-CQA (38–76%), 3-CQA (4–13%), and 4-CQA (4–13%) were the most abundant CQA derivatives of all coffee varieties. The model experiments for adduct formation demonstrated that cysteine binds to CQA via thiol groups and 5-CQA initially isomerizes to 3- and 4-CQA, depending on the conditions, allowing cysteine to bind to two different sites on 3-, 4- or 5-CQA molecules, thus, forming six different Cys-CQA adducts with m/z 476. The reaction was more favored at pH 9, and the adducts proved to be stable up to 90 °C for 10 min and up to 28 days at room temperature. The relative quantification of adducts showed peak area values ranging from 1100 to 3000 in green coffee bean samples, while no adducts were detected in roasted coffee beans. Overall, this work was the first attempt to demonstrate the presence of Cys-CQA adducts in coffee beans and paves the way for further investigations of such adduct formation at the protein level.
URI: https://opendata.uni-halle.de//handle/1981185920/118491
http://dx.doi.org/10.25673/116534
Open Access: Open access publication
License: (CC BY 4.0) Creative Commons Attribution 4.0(CC BY 4.0) Creative Commons Attribution 4.0
Journal Title: Foods
Publisher: MDPI
Publisher Place: Basel
Volume: 13
Issue: 11
Original Publication: 10.3390/foods13111660
Page Start: 1
Page End: 21
Appears in Collections:Open Access Publikationen der MLU

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