TY - JOUR A1 - Islam, Khan Md. Shaiful A1 - Schweigert, Florian J. T1 - Comparison of three spectrophotometric methods for analysis of egg yolk carotenoids JF - Food chemistry N2 - Carotenoids accumulated in the egg yolk are of importance for two reasons. Firstly they are important pigments influencing customer acceptance and secondly they are essential components with positive health effects either as antioxidants or as precursor of vitamin A. Different analytical methods are available to quantitatively identify carotenoids from egg yolk such as spectrophotometric methods described by AOAC (Association of Official Analytical Chemists) and HPLC (High Performance Liquid Chromatography). Both methods have in common that they are time consuming, need a laboratory environment and well trained technical operators. Recently, a rapid lab-independent spectrophotometric method (iCheck, BioAnalyt GmbH, Germany) has been introduced that claims to be less time consuming and easy to operate. The aim of the current study was therefore to compare the novel method with the two standard methods. Yolks of 80 eggs were analysed as aliquots by the three methods in parallel. While both spectrometric methods are only able measure total carotenoids as total beta-carotene, HPLC enables the determination of individual carotenoids such lutein, zeaxanthin, canthaxanthin, beta-carotene and beta-apocarotenoic ester. In general, total carotenoids levels as obtained by AOAC were in average 27% higher than those obtained by HPLC. Carotenoid values obtained by the reference methods AOAC and HPLC are highly correlated with the iCheck method with r(2) of 0.99 and 0.94 for iCheck vs. AOAC and iCheck vs. HPLC, respectively (both p < 0.001). Bland Altman analysis showed that the novel iCheck method is comparable to the reference methods. In conclusion, the novel rapid and portable iCheck method is a valid and effective tool to determine total carotenoid of egg yolk under laboratory-independent conditions with little trained personal. (C) 2014 Elsevier Ltd. All rights reserved. KW - AOAC KW - Carotenoid KW - HPLC KW - iCheck KW - Spectrophotometry KW - Yolk Y1 - 2015 U6 - https://doi.org/10.1016/j.foodchem.2014.09.045 SN - 0308-8146 SN - 1873-7072 VL - 172 SP - 233 EP - 237 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Islam, Khan Shaiful A1 - Khalil, Mahmoud A1 - Männer, K. A1 - Raila, Jens A1 - Rawel, Harshadrai Manilal A1 - Zentek, J. A1 - Schweigert, Florian J. T1 - Effect of dietary alpha-tocopherol on the bioavailability of lutein in laying hen JF - Journal of animal physiology and animal nutrition N2 - 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. KW - carotenoids KW - tocopherol KW - egg yolk KW - bioavailability KW - HPLC KW - iCheck Y1 - 2016 U6 - https://doi.org/10.1111/jpn.12464 SN - 0931-2439 SN - 1439-0396 VL - 100 SP - 868 EP - 875 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Islam, Khan M. S. A1 - Khalil, Mahmoud Abd Elhamid A1 - Maenner, Klaus A1 - Raila, Jens A1 - Rawel, Harshadrai Manilal A1 - Zentek, Jürgen A1 - Schweigert, Florian J. T1 - Lutein Specific Relationships among Some Spectrophotometric and Colorimetric Parameters of Chicken Egg Yolk JF - The journal of poultry science N2 - 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. KW - carotenoid KW - HPLC KW - iCheck KW - lutein KW - spectrophotometry KW - yolk Y1 - 2017 U6 - https://doi.org/10.2141/jpsa.0160065 SN - 1346-7395 VL - 54 SP - 271 EP - 277 PB - Japan Poultry Science Association CY - Tsukuba ER -