Rapid detection of eight vegetable oils on optical thin-film biosensor chips

The development of new and increasingly sophisticated techniques for the authentication of food products continues to be a challenge in public food safety. The authenticity of vegetable oils has become very important as the surge of counterfeit oil into the market increases and consumer confidence decreases. The two methods currently used to authenticate vegetable oils are analysis of species-specific chemical composition by techniques such as chromatography and mass spectrometry, and DNA-based methods such as microarray or qPCR detection. In this study, we have developed a thin-film biosensor chip-based analytical technique for food authentication. Aldehyde-labeled probes were arrayed and covalently attached to a hydrazine-derivatized chip surface. Biotinylated PCR amplicons were then hybridized with the probes. After wash and brief incubations with an anti-biotin IgG-horseradish peroxidase conjugate and a precipitable horseradish peroxidase substrate, biotinylated PCR chain perfectly matched with the probes can be visualized as a color change on the chip surface (gold to blue/purple). This method could detect trace amount of species-specific DNA from food products and has been demonstrated to be effective with eight different vegetative oils. Our results indicated that this assay is rapid, highly sensitive and specific, and can potentially be used as a high throughput detection method.