Researchers develop a new method for rapid authentication of edible oils

Researchers have developed a new method for rapid authentication of edible oils and screening of gutter oils.

Gutter oil is a term used to describe a type of oil that has been repurposed from waste oil. Authentication of edible oils has been a long-term issue in food safety, and becomes particularly important with the emergence and widespread use of gutter oils in recent years in the Asia-Pacific region. However, the conventional analytical approach for edible oils is not only labour intensive and time consuming, but also fails to provide a versatile solution for screening of gutter oils. By setting up a simple analytical protocol and a spectral library of edible oils, the new approach is able to determine the authenticity of a labelled edible oil sample within five minutes.

The conventional approach for edible oil authentication involves sample pre-treatment, chromatographic separation to separate the mixture and, finally, mass spectrometric detection. The whole process can take a few hours to analyse one sample. Using this method, identification of gutter oils mainly involves the detection of certain food residue markers or toxic and carcinogenic chemicals in the sample. Due to the vast diversity of gutter oils, and the fact that target compounds could be removed by processing, a universal strategy to screen gutter oils is not available at present.

Edible oils can be swiftly analysed by comparing MALDI-MS spectrum with those in a spectral library

Researchers at the Food Safety and Technology Research Centre of the Hong Kong Polytechnic University have developed a simplified method for direct analysis of edible oils using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS).

Dr Yao Zhongping demonstrated the simplified method for direct analysis of edible oils. Credit: PolyU

The new MALDI-MS approach involves simple sample preparation, automatic data acquisition and simple data processing. High quality and highly reproducible MALDI-MS spectra results can be obtained using this method and a preliminary spectral database of labelled edible oils has already been set up. Since different types of edible oils have different MALDI-MS spectral patterns, the authenticity of an edible oil sample can then be determined within five minutes by comparing its MALDI-MS spectrum with those of its labelled oil in the established database. Since this method is capable of authenticating edible oils, it also enables a rapid screening of gutter oils.

The research team will establish a more complete MALDI spectral library of various edible oils in the coming two years. In addition, more testing of edible oil samples with different MALDI-MS equipment will be carried out to further validate the new approach.

The research has been published in the journal Analytica Chimica Acta.