Salt distribution in dry-cured ham measured by computed tomography and image analysis

Forty-seven hams were scanned four times by computed tomography (CT) while being manufactured into dry-cured hams. An image-processing algorithm measured CT values in the lean part of the hams and provided line profiles reflecting the magnitude and spatial location of salt gradients. At the end of manufacturing, seven entire hams were dissected and the salt content of the lean part determined. Likewise, in the remaining 40 hams, the lean meat of the slices corresponding to the CT images was dissected, analyzed chemically for NaCl and compared to the CT value. The salt content of entire dry-cured hams correlated well (r2 = 0.94) to the CT value of a 10 mm section located at the center of femur bone, perpendicular to the length axis of the hams. In the same position, significant correlations between the CT values before (r2 = 0.71) and after (r2 = 0.80) the ageing period and actual chemical analysis of the same section were demonstrated. Line profiles illustrating the combined salt distribution and dehydration within a ham related to the physical characteristics of the ham as well as to the manufacturing process. These findings reveal that the effects of altered manufacturing practices can be followed non-invasively, while hams are still in production. Computed tomography combined with appropriate image analysis offers advantages as a non-invasive tool in both research and product development.