Analysis of Aldehydes and Ketones in the Headspace of Heated Pork Fat

Volatile chemicals in the headspace above heated pork fat were purged into aqueous solutions of cysteamine, sodium bisulfite, or methylhydrazine to trap aldehydes and ketones. Nine aldehydes and four ketones were determined as thiazolidine derivatives in traps containing aqueous cysteamine or aqueous sodium bisulfite. The major compounds produced were hexanal, heptanal, and pentanal. In general, aqueous cysteamine was more efficient at trapping carbonyl compounds than was aqueous sodium bisulfite. However, formalydehyde and acetaldehyde were trapped better by sodium bisulfite solution than by cysteamine solution. Acrolein and malonaldehyde were determined as l‐methyl‐2‐pyrazoline and 1‐methylpyrazole, respectively, from the trap containing methylhydrazine. This represents the first time that malonaldehyde has been determined in the vapor phase.