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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.
Tagetes spp. belongs to the Asteraceae family. It is recognized as a major source of lutein ester (lutein esterified with fatty acids such as lauric, myristic and palmitic acids), a natural colorant belonging to the xanthophylls or oxygenated carotenoids. Four species of Tagetes flower (Tagetes tenuifolia, Tagetes erecta, Tagetes patula, and Tagetes lucida) were used to extract lutein and lutein esters with three different methods. The results showed that T. erecta, type "orangeprinz", is the richest source of lutein esters (14.4 +/- 0.234 mg/g) in comparison to other Tagetes spp. No significant differences between extractions of lutein esters with medium-chain triacylglycerols (MCT) oil, orange oil or solvent (hexane/isopropanol) could be observed. MCT oil also improved stability of lutein esters at 100 degrees C for 40 min. Emulsification of MCT oil improved the stability of lutein ester extract against UV light at 365 nm for 72 h. Finally, an emulsion was prepared under food processing conditions, spray dried and its bioavailability investigated in a preliminary human intervention study. The results show a lower resorption, but further data suggest improvements in implementation of such supplements. (c) 2012 Elsevier Ltd. All rights reserved.