American Chemical Society
jf303372a_si_001.pdf (4.16 MB)

Characterization and Modeling of the Interactions between Coffee Storage Proteins and Phenolic Compounds

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journal contribution
posted on 2012-11-21, 00:00 authored by Mostafa Ali, Thomas Homann, Janka Kreisel, Mahmoud Khalil, Ralf Puhlmann, Hans-Peter Kruse, Harshadrai Rawel
This study addresses the interactions of coffee storage proteins with coffee-specific phenolic compounds. Protein profiles of Coffea arabica and Coffea canephora (var. robusta) were compared. Major phenolic compounds were extracted and analyzed with appropriate methods. The polyphenol–protein interactions during protein extraction have been addressed by different analytical setups [reversed-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), matrix-assisted laser desorption ionization–time of flight–mass spectrometry (MALDI–TOF–MS), and Trolox equivalent antioxidant capacity (TEAC) assays], with focus directed toward identification of covalent adduct formation. The results indicate that C. arabica proteins are more susceptible to these interactions and the polyphenol oxidase activity seems to be a crucial factor for the formation of these addition products. A tentative allocation of the modification type and site in the protein has been attempted. Thus, the first available in silico modeling of modified coffee proteins is reported. The extent of these modifications may contribute to the structure and function of “coffee melanoidins” and are discussed in the context of coffee flavor formation.