Duplex real-time PCR method for the detection of sesame (Sesamum indicum) and flaxseed (Linum usitatissimum) DNA in processed food products

Abstract

The development of a duplex real-time polymerase chain reaction (PCR) method allowing the simultaneous detection of sesame and flaxseed DNA in commercial food products is described. This duplex real-time PCR technique is based in the design of sesame- and flaxseed-specific primers based on the ITS1 region and two TaqMan fluorescent probes. The method was positive for sesame and flaxseed, and showed no cross-reactivity for all other heterologous plant and animal species tested. Sesame and flaxseed could be detected in a series of model samples with defined raw and heat-treated sesame in flaxseed, and flaxseed in sesame, respectively, with detection limits of 1.3 mg kg⁻¹ for sesame and 1.4 mg kg⁻¹ for flaxseed. The applicability of the assay for determining sesame and flaxseed in different food matrices was investigated by analysing a total of 238 commercial foodstuffs. This PCR method is useful for highly selective and sensitive detection of traces of sesame and flaxseed in commercial food products.

Keywords:

• duplex TaqMan real-time PCR
• sesame (Sesamum indicum)
• flaxseed (Linum usitatissimum)
• commercial food products
• food allergy

Additional information

Funding

This work was supported by the Programa de Vigilancia Sanitaria [number S2013/ABI-2747] of the Comunidad de Madrid (Spain) and by a project [number AGL2013-48018-R] from the Ministerio de Economía y Competividad (Spain). Inés María López-Calleja Díaz is the recipient of a Juan de la Cierva grant from the Ministerio de Economía y Competividad (Spain). Silvia de la Cruz Ares is the recipient of a fellowship from the Ministerio de Educación, Cultura y Deporte (Spain).