Quality alert from direct discrimination of polycyclic aromatic hydrocarbons in edible oil by liquid-interfacial surface-enhanced Raman spectroscopy

Abstract

Edible oil is easy to be polluted by polycyclic aromatic hydrocarbons (PAHs) in production, processing, storage and use. Rapid screening of oil quality and safety is a huge demand in food industry and government regulation. Usually, sample pretreatment is needed for PAHs detection due to the complexity of the oil base but greatly limits the detection speed. Here we develop a liquid-interfacial surface-enhanced Raman spectroscopy (SERS) technology without sample pretreatment to realize the rapid and direct detection of ultra-trace PAHs in edible oil within 3 min. A quantitative analysis curve of benzopyrene (BaP) content in soybean oil is established in the range of 0.1 ppb–100 ppm with a high coefficient correlation (R2) of 0.9959 in curve fitting. It was found that only 4.5 h of frying would make the BaP content exceed the limit of 10 ppb in the Chinese Food Safety National Standard. Four common PAHs can be quickly identified in frying oil samples collected from special snack streets and the SERS profiles of soybean oil with adulteration of refined gutter oil could be well classified. This study paves a reliable method to rapid analyze edible oil with broad application prospects in the field of grain and oil safety.