Oligopeptides and free amino acids in Parma hams of known cathepsin B activity

Sixteen Parma hams were manufactured following regular standard procedures up to the 13th month of processing and then divided into two groups according to established levels of cathepsin B activity in fresh hams. Each group was selected in order to include the same number of hams with low or high cathepsin B activity. The two groups were further split to be kept for an additional month at two different temperatures (18 and 26 °C) and then analysed for proximate composition, free amino acids and oligopeptides (MW<500 Da). All hams were analysed by sensory analysis (panel test) to be scored for saltiness, bitterness and the flavour of “ageing”. Fresh hams with higher cathepsin B activity were shown by means of two-way ANOVA to yield dry-cured hams more proteolysed (P<0.01), while the higher temperature of the final ageing period seemed to play a major role in lowering ham dryness. Bitterness was particularly well perceived in most proteolysed hams and it was significantly related to the higher amounts of lipophilic amino acids and lipophilic oligopeptides (identified by mass spectrometry), in agreement with the literature. Thus, the endopeptidase activity in fresh hams, together with the presence of specific lipophilic amino acids and oligopeptides in dry-cured hams, can be regarded as a molecular marker of bitter taste development.