Among the volatile chemicals identified in oxidized cooking oils, glyoxal (G), methylglyoxal (MG) and diacetyl (DA) have recently received much attention due to their associations with lung diseases. These three α-dicarbonyl compounds are formed mainly from the oxidation of lipids, such as cooking oils, by heat treatment. One of the main objectives of this study is to analyze these three a-dicarbonyl compounds formed in the headspace of heated cooking oils to provide in situ data for assessing possible inhalation toxicity. Various types of cooking oil samples were heated under simulated cooking conditions. G, MG, and DA formed in the headspaces were collected using a newly developed simultaneous purging-derivatizing-trapping method. The method involves derivatization of three α-dicarbonyl compounds to quinoxalines with <i>o</i>-phenylene diamine and analysis by GC-NPD. More G, MG and DA were produced at higher temperatures and longer heating duration. At the most vigorous condition (at 250 °C for 1 h), amounts of G ranged from 2.07 ± 0.33 μg/mL (Safflower oil) to 5.16 ± 0.86 μg/mL (Grapeseed oil), MG ranged from 2.30 ± 1.02 μg/mL (Safflower oil) to 9.42 ± 1.46 μg/mL (Olive oil), and DA ranged from 0.71 ± 0.03 μg/mL (Vegetable oil) to 2.19 ± 0.29 μg/mL (Olive oil). Among the oil samples examined, the Safflower oil sample generated the least amount of G and MG at all heating conditions (150, 200 and 250 °C for 0.5 and 1 h), whereas, Canola oil produced the most G, MG and DA at low and medium temperatures and short heating duration. Olive oil produced the most of these chemicals at high temperature and long heating duration. This method is useful for the analysis of these α-dicarbonyl compounds formed in various heated oils, including gutter oils (which are often heated multiple times) to assess their toxicities.

Investigation of toxic α-dicarbonyl compounds formed from heated cooking oils

256th National Meeting (2018)

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