Occurrence of thermally induced glycidyl esters and 3-monochloropropane-1,2-diol esters in refined oils and pressed oils manufactured by different processes and associated with human health risks in Taiwan

•Unroasted oils contained limited GE and 3-MCPDE levels despite pressing methods.•Seed roasting temp was the key factor for the occurrence of GEs and 3-MCPDEs.•Except for toasted oils, pressed oils presented lower amounts of 3-MCPDEs and GEs.•Relatively high amounts of 3-MCPDEs and GEs were found in the fruit oil category.•Risks due to exposure to 3-MCPDEs and GEs via refined oils were first assessed. Glycidyl esters (GEs) and 3-monochloropropane-1,2-diol esters (3-MCPDEs) are heat-induced contaminants mainly formed during oil refining. Information on the occurrence of these contaminants in pressed oils is still limited. In this study, 16 oilseeds pressed with a screw press and a hydraulic press had extremely low concentrations of GEs and 3-MCPDEs. Seed-roasting at high temperatures was the principal factor that significantly increased contents of GEs and 3-MCPDEs in pressed oils, in which higher precursor levels were observed. Occurrence data of GE and 3-MCPDE concentrations in refined oils (n = 25) and pressed oils (n = 26) marketed in Taiwan showed that hot-pressed oils had higher concentrations than their cold-pressed counterparts, and average concentrations of refined oils were > 10-fold higher than those of pressed oils. Risk assessment using the margin of exposure (MOE) approach indicated the presence of GEs in edible oils was of concern for food safety, especially for people who frequently use refined oils.