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Xue H.,Nankai University | Xing Y.,Nankai University | Yin Y.,Nankai University | Zhang T.,Nankai University | And 8 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2012

This paper reports the preparation of polyclonal antibodies against a synthetic azo dye, Orange II, and the development of an indirect ELISA to detect Orange II in foods. The sulfonic group of Orange II was modified and linked with carrier protein to synthesise an artificial antigen. Based on the checkerboard titration, the method showed excellent sensitivity (IC50 = 0.61 ng g-1) to Orange II in the linear range of 0.05-10 ng g-1. The antibody had little cross-reactivity with Chromotrope FB, Gardenia Yellow, Ponceau 4R, Sunset Yellow and Sudan dyes. The ELISA had limits of detection (LOD) of 0.22, 0.97 and 0.74 ng g-1 in chilli powder, chilli oil and braised pork, respectively. The limits of quantification (LOQ) of the assay were 0.91 ng g-1 in chilli powder, 1.48 ng g-1 in chilli oil and 1.10 ng g-1 in braised pork. For food products fortified with 1-10 ng g-1 Orange II, the inter- and intra-assay variations were all less than 24.0% and 18.0%, respectively. Therefore, the proposed test could be used as a rapid screening method for Orange II detection in food samples. © 2012 Copyright Taylor and Francis Group, LLC. Source


Zhang T.,Nankai University | Xue H.,Nankai University | Zhang B.,Tianjin Bioradar Biotechnology Co. | Zhang Y.,Nankai University | And 6 more authors.
Journal of the Science of Food and Agriculture | Year: 2012

BACKGROUND: Folic acid (FA) is essential for healthy people (reference daily intake 400 μg day-1) and pregnant women (600 μg day-1). Insufficient intake of FA will increase the risk of neural tube defects in newborns. In this study an indirect enzyme-linked immunosorbent assay was developed for rapid and convenient detection of FA in vitamin-fortified foods. RESULTS: A carbodiimide-modified active ester method was used to synthesise the immunogen (FA-bovine serum albumin (BSA) conjugate) to raise polyclonal antibodies for FA. The coupling ratio of FA with BSA was determined to be 14:1 (molar ratio). The detection limit of the immunoassay was 3.0 ng mL-1 in buffer, 3.52 ng mL-1 in energy drink, 11.91 ng mL-1 in milk and 16.50 ng mL-1 in milk powder. Intra- and inter-assay variability ranged from 6.6 to 15.1%. Analytical recoveries of FA-spiked samples were 88.3-108.9%. CONCLUSION: The immunoassay developed in this study can be used as a simple, rapid and accurate method for fast semi-quantitative and quantitative on-site analysis of FA in food products. © 2012 Society of Chemical Industry. Source


Zhang B.,Jiangsu University | Zhang B.,Tianjin Bioradar Biotechnology Co. | Du D.,Jiangsu University | Meng M.,Nankai University | And 5 more authors.
Food Analytical Methods | Year: 2014

Amaranth (E 123) is a member of azo dyes, and it is allowed to use in various foods. The acceptable maximum addition of amaranth is strictly fixed because of its potential risk to physical health. The objective of this study was to prepare a specific anti-amaranth monoclonal antibody and develop an indirect competitive ELISA for amaranth quantification analysis. The immunogen and the coating antigen were designed by introducing a carboxyl group into amaranth for the conjugation with carrier proteins. Based on the immunogen, the monoclonal antibody exhibits satisfactory performances and the proposed ELISA shows an IC50 of 20.33 ng mL-1. The limit of detection is as low as 3.35 ng mL-1, and the linear standard curve of the method ranges from 3.0 to 243.0 ng mL-1. Additionally, the antibody reflects minimal cross-reactivity (<1 %) with six related food dyes (erythrosine, ponceau 4R, allura red, tartrazine, sunset yellow FCF, and brilliant blue). The recoveries of amaranth spiked beverage samples are in the range of 85.8-100.7 % with low coefficient of variation values (<11.5 %). The data shows that the developed ELISA provides a simple, sensitive, specific, and accurate alternative for amaranth determination and monitoring. Furthermore, it is the first time that icELISA of amaranth is developed based on monoclonal antibodies. © 2013 Springer Science+Business Media New York. Source


Zhang B.,Jiangsu University | Zhang B.,Tianjin Bioradar Biotechnology Co. | Du D.,Jiangsu University | Yin Y.,Nankai University | And 6 more authors.
Food Analytical Methods | Year: 2014

As a synthetic food dye, erythrosine is associated with serious toxicity in inducing thyroid tumors, and the use of erythrosine is strictly regulated in most counties including China. In this study, a direct enzyme-linked immunosorbent assay (ELISA) has been developed for analysis of erythrosine in food products. A highly specific monoclonal antibody (MAb) for erythrosine was produced using erythrosine–bovine serum albumin (BSA) conjugate as an artificial antigen, and horseradish peroxidase (HRP)-labeled MAb for erythrosine was utilized as the detection antibody. Under the optimized condition, the UV absorbance in microplate related well with erythrosine concentration in the range of 0.1–10.0 μg/g. The proposed method could be applied to determine erythrosine in beverage and cookie, with good recoveries (80 –103 %) for the three spiked levels (30, 50, and 100 μg/g), and the relative standard deviations of detected amount were <12.3 %. © 2014, Springer Science+Business Media New York. Source

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