Determination of α-keto acids in pork meat and Iberian ham via tandem mass spectrometry

An analytical method which offers accurate determination and identification of eight α-keto acids (α-ketoglutaric acid, pyruvic acid, 4-hydroxyphenylpyruvic acid, 3-methyl-2-oxobutyric acid, α-keto-γ-methylthiobutyric acid, 4-methyl-2-oxovaleric acid, 3-methyl-2-oxovaleric acid, and phenylpyruvic acid) in pork meat and Iberian ham samples is reported. The method utilises a highly selective and sensitive method of multiple reaction monitoring (MRM) by mass spectrometry. The analytical method is simple (although the chemical derivatisation of the α-keto acids with dansylhydrazine is required), precise (<18% RSD), accurate (90–110%), sensitive (0.01–0.34 mg/kg of defatted and freeze–dried meat depending on the α-keto acid) and linear (R > 0.99) over several orders of magnitude (until 0.01–146.1 mg/kg of defatted and freeze–dried meat depending on the α-keto acid). Using this methodology, α-keto acids were found to be present in pork meat to a low extent, and their concentration increased when they were determined in Iberian ham. This is the first report of the presence of α-keto acids in both pork meats and Iberian hams.

► This study describes the first LC–MS/MS determination of α-keto acids in foods. ► The method requires derivatisation with dansylhydrazine. ► The method has been applied for the determination of α-keto acids in pork meat and Iberian ham. ► Although α-keto acid content is low in pork meat, it increases considerably in Iberian ham. ► This study describes and identifies for the first time the presence of α-keto acids in these meat products.