## 3 Results and Discussion
### Cooking Loss  
The different meat cooking treatments lead to a reduction in weight mainly owing to leaks in the water content of meat. However, water is not the only compound lost during cooking, but other water-soluble components also escaped [16]. This loss of mass occurs principally due to changes in protein chains as a consequence of increased temperature. Specifically, after an overtake of 40 \({}^{\circ}\)C, myofibrillar proteins shrink, favouring coagulation and strengthening the structures of the muscle fibre. All that involves a reduction in the water retention capacity [27]. In this way, cooking losses are dependent on the temperature, on the rate of heating and on the mass transfer process. Hence, the use of different cooking methods will demarcate the differences in water holding capacity of meat, therefore also affecting sensory qualities as tenderness and juiciness [36]. The values determined for cooking losses of pig slices treated by different methods (Table 2) were comparable to those reported in distinct pig muscles by other authors who obtained values ranging between 10-43% [24; 37; 38]. With respect to the use of chestnut in the finishing diet, this seemed to significantly (\(P<0.05\)) increase the cooking loss in all heat treatments, except in grilled. These aftermaths are in disagreement with those obtained by [PERSON] et al. [7] who did not observe that the inclusion of chestnut affected the cooking loss. Nonetheless, our results agree with those showed by [PERSON] et al. [24] who also found that the use of chestnut in the pig diet significantly affected this parameter. These differences could be caused by the existence of non-aqueous fluid losses in addition to water leak, since high temperatures can melt the fat and degrade the structures that contain it [24]. In this respect, it would be logical to think that the initial fat content of raw meat belonging to CH pigs was higher, since in cooked samples this content was significantly (\(P<0.05\)) higher than commercial feed slices (Table 1). This upper content could favour greater losses of non-aqueous fluid during the culinary treatment, therefore increasing cooking losses in pigs fed with chestnut [24]. On the other hand, cooking treatment also significantly (\(P<0.05\)) affected cooking losses (Table 2). The same trend was observed in both diets. The microwaved slices showed the highest cooking loss values (45.43 and 40.66% for CH and CF pigs, respectively), followed by fried samples (42.93% for CH and 37.55% for CF samples) and roasted slices (39.34 and 35.02% for CH and CF pigs, respectively). On the contrary, the grilled samples showed the lowest cooking losses (35.90 and 33.46% for CH and CF samples, respectively). Nevertheless, the cooking losses found by us were similar to those observed by several other authors [14; 25; 34] who determined that microwaving increased the losses in different meats of beef, foal and chicken. The differences in cooking losses found in this study could be due to the appearance of an external layer in samples treated by roasting, grilling and frying, while, in the microwave process, this protective rind is not generated [25; 39]. Besides, the structure and function of protein may also be influenced as a result of the high electromagnetic field used by microwaved, because this generates aggregates that can favour the release of water [40]. Moreover, grilled samples presented the lowest cooking losses and they were similar to those obtained for roasted. As we said, these facts respond to the appearance of an external crust on the surface of the cooked samples, which could act as a physical barrier preventing liquid losses [13; 31]. Furthermore, roasting increases the viscosity of the cooking liquid by favouring the dissolving of the intracellular material in this liquid, thus making its loss more difficult [14]. Oppositely, according to [PERSON] et al. [41], frying leads to enough high cooking losses (42.93% for chestnut and 37.55% for commercial feed) even generating a protective crust.