Detection of Cashew Nut in Foods by a Specific Real-time PCR Method
- PDF / 159,817 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 68 Downloads / 221 Views
Detection of Cashew Nut in Foods by a Specific Real-time PCR Method Alexandra Ehlert & Christine Hupfer & Anja Demmel & Karl-Heinz Engel & Ulrich Busch
Received: 14 December 2007 / Accepted: 11 February 2008 / Published online: 19 March 2008 # Springer Science + Business Media, LLC 2008
Abstract Appropriate detection methods have to be provided to assure the compliance with the recently established regulatory provisions concerning the labeling of allergens in food. Therefore, a novel real-time polymerase chain reaction (PCR) system for the specific and sensitive detection of cashew nut (Anacardium occidentale) was developed. Specificity was checked against DNA from 56 plant and animal species to avoid cross-reactivity to phylogenetically related and other food-relevant organisms. The absolute limit of detection (LOD) was determined to be 0.5 pg genomic cashew DNA and 10 copies, respectively, and the practical LOD examined exemplarily for pesto Genovese was 2 mg/kg. In addition, analysis of different retail samples was performed to demonstrate the suitability of the new assay for manifold applications. Keywords Cashew Nut . Real-time PCR . Validation
Introduction Tree nuts (e.g., hazelnut, walnut, Brazil nut, and cashew) represent a group of the most common food allergens worldwide and therefore labeling according to the annex IIIa of Directive 2003/89/EC has become mandatory since A. Ehlert : C. Hupfer : A. Demmel : U. Busch (*) Bavarian Health and Food Safety Authority, Veterinärstr. 2, 85764 Oberschleißheim, Germany e-mail: [email protected] A. Ehlert : A. Demmel : K.-H. Engel Center of Life and Food Sciences, General Food Technology, Technical University Munich, Am Forum 2, 85350 Freising-Weihenstephan, Germany
November 2005. Allergy to cashew nuts is the second most commonly reported tree nut allergy in the USA (Sicherer et al. 2001). Consumption of cashew nuts as snack or ingredient in diverse food is popular not only in North America and associated allergies are reported globally (Wang et al. 2002a; Wei et al. 2003). Cross-reactivities are described for patients sensitized to pistachio, which belongs to the same botanical family (Fernandez et al. 1995). Appropriate analytical methods are necessary to allow the specific and sensitive detection of cashew and assure the surveillance of labeling requirements by the responsible authorities. Mainly two techniques, protein-based immunoassays and DNA-based polymerase chain reaction, are currently used for the analysis of allergenic food. At present, one sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of cashew nut is described in literature (Wei et al. 2003). This method was developed to detect the specific cashew major protein (CMP or anacardein) at a minimum concentration of 1 mg/kg in food. However, reported cross reactivities to pecan, walnut, pistachio, and sunflower seeds demonstrate limitations of the presented assay. In addition, one polymerase chain reaction (PCR) system has been published for the detection of cashew nut DNA u
Data Loading...
