Characterisation of gas phase organic emissions from hot cooking oil in commercial kitchens.

A large quantity of oily fumes is generated in fast food and Chinese restaurants from cooking oil kept at a high temperature in the kitchens. If these oily fumes are not properly abated, they can be a major source of organic emissions in some dense urban areas with a lot of restaurants such as found in Hong Kong. In the present study, the most commonly used cooking oil, peanut oil, was kept at 260°C in an environment typical of a commercial kitchen that consisted of a two-burner stir-frying cooking range, a single-tank electric fryer, a baffle-type grease extractor and an exhaust duct. Air samples were collected at the inlet of the grease extractor and the exit of the exhaust duct. Organic material was extracted from these samples and examined by gas chromatography and gas chromatography/mass spectrometry. A new extraction protocol using a Soxhlet apparatus and freshly distilled chloroform as the solvent was established in this study. It was noticed that there was no appreciable breakdown of the oil composition at the temperature studied. The efficiency of the grease extractor was determined by obtaining the relative concentrations of gas phase organic composites at the sampling positions.