@article{IslamKhalilMaenneretal.2017, author = {Islam, Khan M. S. and Khalil, Mahmoud Abd Elhamid and Maenner, Klaus and Raila, Jens and Rawel, Harshadrai Manilal and Zentek, J{\"u}rgen and Schweigert, Florian J.}, title = {Lutein Specific Relationships among Some Spectrophotometric and Colorimetric Parameters of Chicken Egg Yolk}, series = {The journal of poultry science}, volume = {54}, journal = {The journal of poultry science}, publisher = {Japan Poultry Science Association}, address = {Tsukuba}, issn = {1346-7395}, doi = {10.2141/jpsa.0160065}, pages = {271 -- 277}, year = {2017}, abstract = {Lutein is an essential dietary carotenoid with health benefits and is inter alia responsible for the colouration of egg yolk. The relationship between lutein accumulation and egg yolk colouration was therefore studied in more detail. After feeding a low-luteine diet for 21 days, 14 birds (Lohmann brown hens aged 20 weeks) were fed a diet containing marigold (80 mg lutein/kg feed) and 14 other birds were fed a diet containing oleoresin (45 mg lutein/kg feed) for 21 days; for both groups of birds, this feeding period was followed by withdrawal for 21 days. The Roche Yolk Colour Fan (RYCF) score (0 to 15, where higher values denote greater colour intensity; R-2=0.87; P<0.01) and redness (R-2=0.89; P<0.01) increased with increasing lutein content of egg yolk. Total carotenoid content had a poor relationship with lightness (R-2=0.13; P>0.05) and yellowness (R-2=0.12; P>0.05) of the yolk. It may be concluded that increased lutein is potentially responsible for an increased RYCF score and redness (a*), but decreased yellowness (b*) and lightness (L*), of egg yolk.}, language = {en} } @article{AliHomannKhaliletal.2013, author = {Ali, Mostafa and Homann, Thomas and Khalil, Mahmoud and Kruse, Hans-Peter and Rawel, Harshadrai Manilal}, title = {Milk whey protein modification by coffee-specific phenolics effect on structural and functional properties}, series = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, volume = {61}, journal = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, number = {28}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-8561}, doi = {10.1021/jf402221m}, pages = {6911 -- 6920}, year = {2013}, abstract = {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.}, language = {en} } @article{AliHomannKreiseletal.2012, author = {Ali, Mostafa and Homann, Thomas and Kreisel, Janka and Khalil, Mahmoud and Puhlmann, Ralf and Kruse, Hans-Peter and Rawel, Harshadrai Manilal}, title = {Characterization and modeling of the interactions between coffee storage proteins and phenolic compounds}, series = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, volume = {60}, journal = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, number = {46}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-8561}, doi = {10.1021/jf303372a}, pages = {11601 -- 11608}, year = {2012}, abstract = {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.}, language = {en} } @article{KhalilRailaAlietal.2012, author = {Khalil, Mahmoud and Raila, Jens and Ali, Mostafa and Islam, Khan M. S. and Schenk, Regina and Krause, Jens-Peter and Schweigert, Florian J. and Rawel, Harshadrai Manilal}, title = {Stability and bioavailability of lutein ester supplements from Tagetes flower prepared under food processing conditions}, series = {Journal of functional food}, volume = {4}, journal = {Journal of functional food}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1756-4646}, doi = {10.1016/j.jff.2012.03.006}, pages = {602 -- 610}, year = {2012}, abstract = {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.}, language = {en} } @article{IslamKhalilMaenneretal.2016, author = {Islam, Khan Shaiful and Khalil, Mahmoud and M{\"a}nner, K. and Raila, Jens and Rawel, Harshadrai Manilal and Zentek, J. and Schweigert, Florian J.}, title = {Effect of dietary alpha-tocopherol on the bioavailability of lutein in laying hen}, series = {Journal of animal physiology and animal nutrition}, volume = {100}, journal = {Journal of animal physiology and animal nutrition}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0931-2439}, doi = {10.1111/jpn.12464}, pages = {868 -- 875}, year = {2016}, abstract = {Lutein and its isomer zeaxanthin have gained considerable interest as possible nutritional ingredient in the prevention of age-related macular degeneration (AMD) in humans. Egg yolk is a rich source of these carotenoids. As an oxidative sensitive component, antioxidants such as -tocopherol (T) might contribute to an improved accumulation in egg yolk. To test this, chickens were fed lutein esters (LE) with and without -tocopherol as an antioxidant. After depletion on a wheat-soya bean-based lutein-poor diet for 21days, laying hens (n=42) were equally divided into three groups and fed the following diets for 21days: control (basal diet), a LE group (40mg LE/kg feed) and LE+T group (40mg LE plus 100mg T/kg feed). Eggs and blood were collected periodically. Carotenoids and -tocopherol in yolk and blood plasma were determined by HPLC. Egg yolk was also analysed for total carotenoids using a one-step spectrophotometric method (iCheck(())). Lutein, zeaxanthin, -tocopherol and total carotenoids in egg yolk were highest after 14days of feeding and decreased slightly afterwards. At the end of the trial, eggs of LE+T group contained higher amount of lutein (13.72), zeaxanthin (0.65), -tocopherol (297.40) and total carotenoids (21.6) compared to the LE group (10.96, 0.55, 205.20 and 18.0mg/kg, respectively, p<0.05). Blood plasma values of LE+T group contain higher lutein (1.3), zeaxanthin (0.06) and tocopherol (20.1) compared to LE group (1.02, 0.04 and 14.90mg/l, respectively, p<0.05). In conclusion, dietary -tocopherol enhances bioavailability of lutein reflecting higher content in egg yolk and blood plasma. Improved bioavailability might be due to increased absorption of lutein in the presence of tocopherol and/or a greater stability of lutein/zeaxanthin due to the presence of -tocopherol as an antioxidant.}, language = {en} } @phdthesis{Khalil2013, author = {Khalil, Mahmoud Abd Elhamid}, title = {Improvement of stability and bioavailability of lutein and lutein ester in emulsion-based delivery systems}, address = {Potsdam}, pages = {145 S.}, year = {2013}, language = {en} } @article{FredeHenzeKhaliletal.2014, author = {Frede, Katja and Henze, Andrea and Khalil, Mahmoud and Baldermann, Susanne and Schweigert, Florian J. and Rawel, Harshadrai Manilal}, title = {Stability and cellular uptake of lutein-loaded emulsions}, series = {Journal of functional food}, volume = {8}, journal = {Journal of functional food}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1756-4646}, doi = {10.1016/j.jff.2014.03.011}, pages = {118 -- 127}, year = {2014}, abstract = {The carotenoid lutein can improve human health. Since only a fraction is absorbed from food, lutein supplementation might be recommended. Emulsions could be good carrier systems to improve the bioavailability of lutein. Six different emulsifier compositions were used in this study to prepare lutein-loaded emulsions: beta-lactoglobulin, beta-lactoglobulin/lecithin, Biozate 1, Biozate 1/lecithin, Been 20 and Tween 20/lecithin. The droplet size, resistance to creaming, lutein stability, cytotoxicity and lutein uptake by HT29 cells were investigated. The whey protein beta-lactoglobulin, the whey protein hydrolysate Biozate 1 and the combination with lecithin brought the most promising results. The small droplet sizes and resistance to creaming were an indication of physical stable emulsions. Furthermore, these emulsifiers prevented oxidation of lutein. The choice of emulsifier had a strong impact on the uptake by HT29 cells. The highest lutein absorption was observed with the combination of Biozate 1 and lecithin.}, language = {en} }