Full automated robotic method for the determination of chloride, nitrite and nitrate in cured meat products.

A completely automated method to determine the most common parameters in cured meat products is proposed. The approach to full automation is based on the coupling of a robotic station for development of preliminary operations (namely weighing of the sample, grinding, leaching, filtration and transport to the aspiration zone) and a continuous unsegmented manifold for derivatisation and spectrophotometric monitoring of the reaction coloured products. This assembly works in an unattended fashion thus eliminating the bottleneck produced by the determination of these parameters in routine laboratories. The good agreement between results obtained by the proposed method and those from conventional methods for target analytes confirms its excellent performance and usefulness.

Activity of cathepsin B, D, H and L in Spanish dry-cured ham of normal and defective texture.

Thirty-six specimens of Spanish dry-cured ham from 18 different batches were studied to determine the influence of endogenous enzymes on the textural quality of the end product. It was shown that, the residual enzyme activity of cathepsins B+L is a reliable indicator of textural defects associated with strong proteolysis in Spanish dry-cured ham. In contrast, the activity of cathepsin B, which varied widely among samples, was less influential. Salt levels can have a moderate effect on the residual enzyme activities. Other compositional parameters also influence the properties of the end product; the amount of protein in semimembranosus muscle was found to be less and the moisture greater in texturally defective specimens. Also, the efficiency of the drying-curing process was less in hams yielding poor textures.

Relationship between pH before salting and dry-cured ham quality.

The effect of pH before salting on pork quality was studied in two sets of experiments: 904 hams, set A; and 104 hams, set B; the latter was used to verify the results from A. After pH measurements, the hams were subjected to the traditional process for producing Spanish dry-cured ham and then evaluated by an expert panel to correlate the sensory characteristics to the pH measurement before salting. The parameters evaluated were pastiness, softness, anomalous cut colour, crusting and white spots. Moisture, non-protein nitrogen, salt, protein, nitrate and nitrite were determined in samples from both experiments. The results obtained in experiment A showed that pastiness is closely related to the pH before salting (p<0.001), but not softness. From the receiver operating characteristics curve, a cut-off point of pH of 5.55 was selected to classify the raw material in two groups: normal-pH and low-pH hams. The pH before salting can also be correlated with the appearance of anomalous cut colour and crusting in hams. White spots were absent in both pH groups. Regarding compositional parameters, there were significant differences in moisture (p<0.001), salt (p<0.001), protein (p<0.001), non-protein nitrogen (p<0.001) and nitrate (p<0.05) contents between low-pH and normal-pH hams. The results from experiment B, confirmed the relationship between pH before salting and the appearance of defective texture and colour in the final product. Also results from experiment B confirmed the compositional parameters found in experiment A. Thus, the pH before salting is a good predictor for meat quality allowing the classification of the raw material in the first stage of manufacture. After classification, some modifications to the processing can improve the final characteristics of dry-cured hams.