TY - JOUR A1 - Ali, Mostafa A1 - Homann, Thomas A1 - Khalil, Mahmoud A1 - Kruse, Hans-Peter A1 - Rawel, Harshadrai Manilal T1 - Milk whey protein modification by coffee-specific phenolics effect on structural and functional properties JF - Journal of agricultural and food chemistry : a publication of the American Chemical Society N2 - A suitable vehicle for integration of bioactive plant constituents is proposed. It involves modification of proteins using phenolics and applying these for protection of labile constituents. It dissects the noncovalent and covalent interactions of beta-lactoglobulin with coffee-specific phenolics. Alkaline and polyphenol oxidase modulated covalent reactions were compared. Tryptic digestion combined with MALDI-TOF-MS provided tentative allocation of the modification type and site in the protein, and an in silico modeling of modified beta-lactoglobulin is proposed. The modification delivers proteins with enhanced antioxidative properties. Changed structural properties and differences in solubility, surface hydrophobicity, and emulsification were observed. The polyphenol oxidase modulated reaction provides a modified beta-lactoglobulin with a high antioxidative power, is thermally more stable, requires less energy to unfold, and, when emulsified with lutein esters, exhibits their higher stability against UV light. Thus, adaptation of this modification provides an innovative approach for functionalizing proteins and their uses in the food industry. KW - coffee phenolic compounds KW - whey proteins KW - antioxidants KW - protein-phenol interactions KW - modeling KW - functionalizing proteins Y1 - 2013 U6 - https://doi.org/10.1021/jf402221m SN - 0021-8561 VL - 61 IS - 28 SP - 6911 EP - 6920 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Ali, Mostafa A1 - Homann, Thomas A1 - Kreisel, Janka A1 - Khalil, Mahmoud A1 - Puhlmann, Ralf A1 - Kruse, Hans-Peter A1 - Rawel, Harshadrai Manilal T1 - Characterization and modeling of the interactions between coffee storage proteins and phenolic compounds JF - Journal of agricultural and food chemistry : a publication of the American Chemical Society N2 - 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. KW - Coffee beans KW - storage proteins KW - phenolic compounds KW - antioxidants KW - protein-phenol interactions KW - modeling Y1 - 2012 U6 - https://doi.org/10.1021/jf303372a SN - 0021-8561 VL - 60 IS - 46 SP - 11601 EP - 11608 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Rawel, Harshadrai Manilal A1 - Huschek, Gerd A1 - Sagu Tchewonpi, Sorel A1 - Homann, Thomas T1 - Cocoa Bean Proteins-Characterization, Changes and Modifications due to Ripening and Post-Harvest Processing JF - Nutrients N2 - The protein fractions of cocoa have been implicated influencing both the bioactive potential and sensory properties of cocoa and cocoa products. The objective of the present review is to show the impact of different stages of cultivation and processing with regard to the changes induced in the protein fractions. Special focus has been laid on the major seed storage proteins throughout the different stages of processing. The study starts with classical introduction of the extraction and the characterization methods used, while addressing classification approaches of cocoa proteins evolved during the timeline. The changes in protein composition during ripening and maturation of cocoa seeds, together with the possible modifications during the post-harvest processing (fermentation, drying, and roasting), have been documented. Finally, the bioactive potential arising directly or indirectly from cocoa proteins has been elucidated. The state of the art suggests that exploration of other potentially bioactive components in cocoa needs to be undertaken, while considering the complexity of reaction products occurring during the roasting phase of the post-harvest processing. Finally, the utilization of partially processed cocoa beans (e.g., fermented, conciliatory thermal treatment) can be recommended, providing a large reservoir of bioactive potentials arising from the protein components that could be instrumented in functionalizing foods. KW - cocoa processing KW - cocoa proteins KW - classification KW - extraction and characterization methods KW - fermentation-related enzymes KW - bioactive peptides KW - heath potentials KW - protein-phenol interactions Y1 - 2019 U6 - https://doi.org/10.3390/nu11020428 SN - 2072-6643 VL - 11 IS - 2 PB - MDPI CY - Basel ER -