Chemical changes in volatile aldehydes and ketones from subcutaneous fat during ripening of Iberian dry-cured ham. Prediction of the curing time

Abstract

Changes in volatile aldehyde and ketone amounts from subcutaneous fat have been evaluated during the dry-curing process (987days) of Iberian ham by purge & trap-gas chromatography–mass spectroscopy method, using the same hams for the first time. The subcutaneous adipose tissues of ten hams obtained from five Iberian pigs fed on acorns and pasture were sampled and analyzed periodically during whole processing time. Fifteen aldehydes and six ketones have been identified, all previously described except the 2,4-pentadienal that has been identified for the first time. A LDA was applied and the two discriminant functions were obtained using backward stepwise analysis retaining the variables: 4-octen-3-one, 2-methyl-butanal, butanal, 2-decenal, 2-heptanone, decanal, 2,4-pentadienal, pentanal, hexanal, 2-butanone, octanal and 2-octanone. A complete separation between the three periods was obtained, indicating that the retained variables are powerful descriptors to characterize samples from these three dry-curing periods. The ratio between total aldehydes and ketones was used to predict the curing time.