3.1. Effect of Processing Stage and Breed on Physicochemical Parameters, Salt Content, Microbial Analyses, and Mineral Composition
Table 1 shows the evolution of the physicochemical parameters and salt content of reduced boneless dry-cured ham obtained from commercial crosses of Iberian and white pigs at different processing stages.
The processing stage affected all physicochemical parameters studied in boneless dry-cured ham of different breeds.
The moisture content in the dry-cured RIB ham was significantly reduced (
p ≤ 0.001), mainly between the drying stage and the final product, whereas the intramuscular fat content increased (
p ≤ 0.05), as observed in the protein values. In this parameter, the increase was more marked between the raw muscle and the drying stage, without observing significant differences between the final product (stage V) and the previous processing stages (
p ≥ 0.05); this was observed in both studied breeds. A similar evolution was observed in the NPN, with significantly increased values mainly between the end of postsalting (stage III) and the end of processing (stage V) (
p ≤ 0.001) in RIB and RWC. Consequently, PI also increased significantly during processing (
p ≤ 0.001). The increase in proteolytic activity of dry-cured hams during their ripening stage (stages IV and V) has been related to the rise in temperature that takes place at these manufacturing stages, resulting in a greater activity of proteolytic enzymes [
37]. Physicochemical modifications were in line with what is observed in other dry-cured hams throughout processing [
38,
39].
NaCl and ash concentrations increased significantly, mainly at the start of postsalting stage due to the incorporation of curing salts associated with the manufacturing process (
p ≤ 0.001 in both cases). A marked increase was observed in the NaCl values of both breeds between stages I (raw muscle) and II (start of postsalting), as well as between the end of postsalting and the last two phases of the production process, due to the decrease in moisture, which takes place during the last stages of production. This phenomenon was also observed in the ash concentration of RWC dry-cured ham (
Table 1), which reached its maximum values in the last two stages of the production process, whereas the ash values of the RIB dry-cured ham remained stable between the start of the postsalting stage (stage II) and the final product (stage V). Correct diffusion of salt (NaCl) was achieved with the processing method, with the concentration in dry-cured RWC of 3.77% and 2.86% in the RIB final product (processing stage V). Correct diffusion of salt during processing is important because of the role this ingredient plays. It will not only influence the texture, flavor, and aroma of the product, but will also ensure an optimal microbiological quality [
40].
Regarding breed, moisture (p ≤ 0.001), fat (p ≤ 0.001), protein (p ≤ 0.001), TN (p ≤ 0.001), NPN (p ≤ 0.001), PI (p ≤ 0.05), NaCl (p ≤ 0.05), and ash (p ≤ 0.001) were also affected.
Moisture values and protein content were significantly higher in dry-cured RWC ham (
p ≤ 0.001), in all stages of processing, in contrast to the fat values, in which the RIB dry-cured ham presented more than double the fat content of RWC (
p ≤ 0.001), due to the high adipogenicity of native pig breeds [
41]. These differences between breeds in fat and protein content were like those observed by Lorido et al. [
23].
NPN values were significantly higher in RWC dry-cured ham (
p ≤ 0.001) throughout the manufacturing process. As expected, the PI was significantly lower in RIB (
p ≤ 0.05), due to the higher calpains and cathepsins activity in the dry-cured hams of commercially crossed white pigs [
42]. In contrast, Córdoba et al. [
43] described that proteolysis in Iberian hams could be higher than other types of dry-cured hams, such as Parma ham, due to the longer ripening time and the higher temperatures reached during the process. The PI in both breeds was lower than values reported by Schivazzapa and Virgili [
44] in reduced salt Italian dry-cured hams obtained from pig crosses of Large White, Landrace, and Duroc.
The PI observed in the TIB final product (18.58%; value not included in
Table 1), was slightly lower than RIB and was like those described in other dry-cured hams [
45].
An adequate control of the ripening phase of reduced salt dry-cured hams is essential to assess the prolongation of this processing stage, to avoid texture or aroma problems [
46], because free amino acids—resulting from the intense proteolysis the product undergoes during manufacturing—will contribute greatly to developing the sensory characteristics of the final product [
47].
NaCl and ash concentrations were also higher in RWC dry-cured ham (
p ≤ 0.001) for all the processing stages. Consistent with salt reduction, the NaCl content in RIB and RWC was less than the values reported by some authors for dry-cured ham from commercial crosses of Croatian white pigs (between 5.76% and 7.01%) [
48] and other native breeds (5.75%) [
49] for the final product (processing stage V).
The average NaCl concentration was 4.11% in the traditionally manufactured Iberian dry-cured hams, thus a reduction of 30% compared to RIB. In RWC dry-cured hams, a reduction of 27.5% was reached, with an average value considered of 5.20% in traditional white dry-cured ham [
50]. According to the Annex of Regulation (EC) No 1924/2006 [
19], the claim ‘Reduced in salt’ could be included in the labeling of these products, because the indicated 25% reduction has been exceeded. Pinna et al. [
51] also achieved a considerable reduction in salt content in typical Italian dry-cured hams by modifying salt added and the salting time.
Despite reducing the salt content of dry-cured hams, it does not compromise the stability and safety of the final product, as they meet the required microbiological conditions established. In this way, the counts of
Listeria monocytogenes (in 25 g),
Salmonella (in 25 g),
E. coli (cfu/g),
Staphylococcus (cfu/g),
Clostridium (cfu/g), Mesophilic aerobes (cfu/g), and Enterobacteria (cfu/g) complied with the limits established by Regulation (EC) No 2073/2005 [
52], relative to the microbiological criteria applicable to food products.
Table 2 includes the evolution of the mineral composition of reduced boneless dry-cured ham obtained from commercial crosses of Iberian and white pigs throughout processing.
The processing stage (
p ≤ 0.001) and breed (
p ≤ 0.001) significantly modified the concentration of Na, K, Mg, and P. The amount of Zn was only significantly affected (
p ≤ 0.001) by the processing stage, showing higher values in the final stages. Na values increased from the beginning of postsalting (processing stage II) and were always higher in RWC than in RIB, as was observed for NaCl (
Table 1). The concentration of the rest of the minerals did not change significantly (
p > 0.05). The concentration of K, Mg, P, Fe, and Zn was higher than observed in a previous study [
53], whereas Na and Mn were lower. Ca values were similar; however, no references could be found for B and Cu.
3.2. Free Amino Acids
Results for the effect of Iberian dry-cured ham type and the effect of breed on free amino acid (FAA) content in the final product (processing stage V) are shown in
Table 3.
None of the FAA studied was affected by the processing of different Iberian dry-cured ham (traditional and reduced salt boneless manufactured) (
p > 0.05). The same was observed regarding the total FFA (
p > 0.05). Therefore, peptidase activity was not significantly affected (
p > 0.05) by salt reduction (30%) although total FAA content was slightly higher in RIB. These findings disagreed with the study by Cittadini et al. [
54], in which an increase in proteolytic phenomenon was observed as the NaCl content decreased.
Abellán et al. [
55] described that the concentration of amino acids reflects the proteolysis achieved during the ripening stage of dry-cured meat products. Considering the data obtained in PI, NPN (
Table 1), and the total FFA (
Table 3), the proteolysis of dry-cured Iberian ham followed an expected evolution, despite the reduction in salt content. According to Lorenzo et al. [
56], the proteolytic reactions are promoted in meat products with a partial replacement of sodium.
The differences in amino acid concentration of boneless dry-cured ham of different breeds were not significant (
p > 0.05). Krvavica et al. [
57] also found no effect of breed on the FFA content in two types of dry-cured Croatian ham obtained from different genotypes of commercial white pig crosses.
The differences in the PI between the two breeds studied (
Table 1) could be explained by a higher protease activity (calpain and cathepsins) of RWC dry-cured hams. However, no differences in FAA concentration were observed, probably because the breed did not affect peptidases activity.
3.3. Instrumental Color and Texture Profile
Table 4 shows the effect Iberian dry-cured ham type and the effect of breed on the instrumental color.
The instrumental color parameters were not affected by different processes for Iberian dry-cured ham (
p > 0.05 in all cases), agreeing with the data obtained by Lorenzo et al. [
58], who studied the effect of partial replacement of NaCl with other salts on dry-cured
lacón. In contrast, Tejada et al. [
32] observed an effect of different salt formulation on the color parameters of another derived meat pig product (Spanish
chorizo) describing a higher luminosity value (L*) in the product cured with a traditional formulation (with NaCl as the main ingredient), as well as higher values of b*, C*, and h*. No breed effect on color parameters was observed (
p > 0.05 in all cases). The range of L*, a*, and b* values obtained in the two types of Iberian dry-cured ham studied (TIB and RIB) and in the reduced salt dry-cured ham, obtained from white commercial pig crosses, were higher than dry-cured ham obtained from the Celta pig by Bermúdez et al. [
38].
Table 5 shows the effect Iberian dry-cured ham type and breed on the instrumental texture.
The processing of Iberian dry-cured ham and the breed had a significant effect on C1 hardness, C2 cohesiveness, C2 gumminess, C2 chewiness, and C2 hardness (
Table 5). All cited texture profile parameters were higher in RIB compared to TIB. Despite the differences observed in the TPA, consumers did not report an effect of processing between the two Iberian dry-cured hams studied (
Table 6). Although the TPA confirmed the differences found in the sensory analysis regarding breed, where consumers scored RIB texture better than RWC’s (
Table 6).
The data here are partially consistent with the study of Tejada et al. [
32], in which the authors found an effect of salt reduction on hardness, cohesiveness, gumminess, and chewiness in another derived meat pig product. However, TPA hardness values where higher in the NaCl reduced product of the cited study, contrary to the data obtained in this study, as RIB showed higher values. The authors associated this phenomenon with the inhibition of cathepsins by NaCl, which reduces the proteolysis activity affecting the texture of the product. Therefore, we can conclude that proteolysis of RIB was not affected significantly, considering TPA hardness values (
Table 5) and according to data obtained for the FFA (
Table 3). Regarding breed, RIB’s higher hardness values could be related to the lower moisture content obtained than the RWC dry-cured ham (
Table 1).
Cittadini et al. [
54] also studied the effect of NaCl replacement by other chloride salts on TPA parameters (hardness, springiness, cohesiveness, gumminess, and chewiness) of foal Cecina, a similar dry-cured product, but in contrast to our result, they only found significant differences in the springiness.
3.4. Consumer Sensory Acceptability and Preference
Table 6 shows the acceptability scores for TIB, RWC, and RIB dry-cured hams given by the consumer panel.
Regarding the type of processing, the panel of consumers scored all the attributes in RIB dry-cured ham higher than the TIB dry-cured ham, although none were significantly different (
p > 0.05). Therefore, the consumer acceptability of sensory traits is similar in both types of dry-cured ham; thus, the reduction of the salt content and the deboning do not affect the organoleptic characteristics of the Iberian dry-cured ham. The results agree with other studies of cured meat in which the palatability and texture were not compromised with the reduction of salt in respect to the traditional method [
59]. However, contrasting results have been reported in cooked ham products, where texture, flavor, and overall consumer acceptability were significantly affected by salt reduction [
60].
In Italian dry-cured ham obtained from white commercial pig crosses, a greater acceptability was observed in salt-reduced dry-cured ham in respect to the same product processed after traditional manufacturing [
44].
Both types of Iberian ham (TIB and RIB) obtained global acceptance scores above 4 (I like) on the scale of 1–5, so it can be asserted that the consumer accepts Iberian dry-cured ham more.
Regarding the effect of the breed on the consumer acceptability of dry-cured ham, all sensory traits were scored significantly high by the untrained panel in dry-cured RIB ham compared to dry-cured RWC ham (p ≤ 0.05).
The intramuscular fat content of the product has been described among the main composition parameters that influence the organoleptic quality in dry-cured products [
61]. As has been described, this parameter was significantly higher in RIB dry-cured ham compared to RWC dry-cured ham, thus data agreed with other studies on Iberian pig dry-cured products [
62] and other native breeds [
63], where it was observed that products obtained from autochthonous breeds were better valued by consumers.
In the preference study, 6.38% of consumers preferred the RWC dry-cured ham, 63.83% the RIB dry-cured ham, and 29.79% the TIB. Therefore, from a consumer viewpoint, the reduction of salt in dry-cured ham improved the perception.
Regarding the preference between the two Iberian products, 70% of the consumers chose the reduced salt product, although no significant differences were detected in the evaluation of the acceptance of the salty taste (
Table 6).