Physico-chemical Characterization of "Bone Taint" in Spanish Dry-cured Hams

Samples of Spanish dry-cured hams were analyzed using several physico-chemical parameters (moisture content, chlorides, water activity, nitrate, nitrite, total volatile basic nitrogen [TVBN], pH, and oxidation-reduction potential [E_h]). The samples (n = 76) were taken from three basic types of dry-cured hams produced in Spain: slow-cured hams from white pigs (n = 39), fast-cured hams from white pigs (n = 15), and hams from black-skinned Iberian pigs (n = 22). Overall, 56 samples (73.7%) showed the "bone taint" condition, and the remaining 20 hams (26.3%) were normal, and therefore considered as a control group. The objective of this research was to establish the possible circumstances that determine the alteration by means of the differences found in the values of the analyzed measurements in both groups of samples (altered versus normal ones). The hams with "bone taint" were, in general terms, those with a higher TVBN content, a greater pH, and a lower E_h, attributable to an anomalous development of the proteolytic phenomena. The conjunction of a lower concentration of chlorides, greater moisture content, and a higher a_w in the affected hams may have created the conditions favorable for tissue enzyme and/or microbial activity.