Monitoring changes in 3-monochloropropanediol, 2-monochloropropanediol, and glycidyl esters of palm olein after repeated deep frying of commercial chicken nuggets

The present work examined the changes in 3-monochloropropanediol ester (3-MCPDE), 2-monochloropropanediol ester (2-MCPDE), and glycidyl ester (GE) in palm olein after repeated deep frying of commercial chicken nugget samples at 160 and 180°C. Free fatty acid (FFA) composition, p-anisidine value (p-AV), and specific extinction at 232 and 268 nm (K232 and K268) were determined. Results indicated that the concentrations of MCPDEs and GE in the frying oil after the fourth frying cycle were higher than the initial concentrations, except for the GE concentration when fried at 180°C. The content of 3-MCPDE for fried chicken nugget samples increased during deep frying at 160 and 180°C, but its 2-MCPDE and GE levels decreased. FFA contents in frying oil were found to increase over time; however, the increases were determined to be non-significant. p-AV increased linearly with higher values in the 180°C frying system. No significant relationship was found between the concentration of MCPDEs and GE formed in the frying oil with oil oxidation in the repeated deep frying of up to four cycles. All of the oil qualities were within safe consumption levels.