## 3 Results and Discussion
### Texture Analysis  
Texture is one of the most important sensory qualities of meat, affecting consumer acceptance [27]. Inside the texture parameters, shear force is a good indicator of meat hardness. These criteria supply good information about the degree of denaturation of myofibrillar proteins (fundamentally of the actomyosin complex), as a consequence of the contraction of muscle fibres produced by the cooking treatment [42]. Then again, collagen is also a compound that has been related to the hardness of meat, but previous studies have shown that, in the case of pork meat, it showed low correlation coefficients with tenderness [43]. The outcomes obtained for the shear force in our research (Table 2) were slightly higher than those obtained by other researchers [44; 45; 46] in the _Longissimus_ pig muscle, since the shear force determined by them was between 32 and 49 N. Moreover, the values found in the present research were also higher than those described in the raw _Biceps femoris_ muscle (about 18 N) from Celta pig [33]. This fact was expected, since raw meat is not comparable to cooked meat. In contrast, [PERSON] et al. [24] and [PERSON] et al. [7] obtained higher values than our in _Longissimus_ pig muscle (100-135 N). These differences in texture may be due to the fact that Celta pigs, like those used in this study, present greater physical activity during breeding and their slaughter age is higher compared to pigs of improved breeds [7]. Additionally, as reported by [PERSON] et al. [7], the type of muscle affected the texture parameters. Thus, the different muscles studied among researches could also explain the differences. Following hardness, all of our slices could be considered as \"though\" according to [PERSON] et al. [47], since the values obtained for this parameter were higher than 52.68 N. In the present study, the shear force value was not influenced by diet of cooking treatment. This fact is in accordance with data obtained by [PERSON] et al. [24] and [PERSON] et al. [7], who observed that the inclusion of chestnut in pigs diet did not significantly affect texture parameters of meat. Regarding cooking treatments, several works showed that tenderness was strongly influenced by the temperature and cooking time [13; 48]. Even so, with the outcomes achieved, it seems that there is a tendency for the fried treatment to increase the hardness of the samples from CH pigs (81.18 N) with respect to the other ones (77.09, 73.95 and 73.50 N for microwaved, roasted and grilled treatments, respectively). In the case of CF pigs, roasted samples obtained the highest shear force (86.92 N), followed by fried (80.90 N) and microwaved (77.57 N) samples. Eventually, grilled was the method that supplied the least hardness for both diets (73.50 N for CH and 71.43 N for CF samples). In the same line, [PERSON] et al. [34] evidenced this trend, because they concluded that grilling in foal meat also generated less hardness slices compared to other treatments (roasted, fried and microwaved). Besides, according to [PERSON] et al. [49] the Pearson correlation demonstrated that shear force was positively related to cooking loss (r = 0.301; \(P>0.05\); and r = 0.562; \(P<0.01\) for CH and CF, respectively). However, there were only significant (\(P<0.01\)) differences in CF samples.