# Quality of Pork Loin Subjected to Different Temperature-Time Combinations of Sous Video Cooking
## 3 Results and Discussion
### Proximate Composition  
The moisture content in raw pork loin was 71.98% and in the cooked meat it was in the range of 67.37-70.39% (Table 1). The lowest moisture level was found in the meat heated at 63 \({}^{\circ}\)C/5 h and the highest in the meat heated at 57 \({}^{\circ}\)C/3 h. The loin samples differed significantly depending on the heating temperature (_p_ < 0.001) and time (_p_ < 0.01) applied. In general, the higher the cooking temperature and the longer the cooking time used, the lower the moisture content in the pork samples. Our results confirm the observations noted in other studies [20; 22; 41; 42]. In the review by [PERSON] [39], it was reported that with increasing temperature, the transverse shrinkage of muscle fibres at 40-60 \({}^{\circ}\)C and then collective longitudinal shrinkage of the connective tissue network and the muscle fibres at 60-70 \({}^{\circ}\)C cause expulsion of water, which is held in the spaces between the thick and thin filaments in the muscle, and which represents most of the water present in the muscle [35]. Another reason for water loss from meat during cooking is protein denaturation, which leads to less water held by capillary forces within protein structures [43]. The heat treatment of meat causes a decrease in the number of acidic and basic groups of proteins, which in turn affects the pH value of meat and the change in the isoelectric point of proteins, and, as a result, the moisture-holding capacity of proteins [34]. [PERSON] and [PERSON] [36] reported that the low temperature used during sous vide cooking of meat helped to preserve cellular structure and increase water retention capacity compared to traditional cooking, which in turn promoted solubilisation and gelation of the connective tissue and ensured that the final products are tender and juncy. The fat content in the cooked meat samples ranged from 3.67 to 4.14%, with the lowest fat content recorded in pork loin heated at 63 \({}^{\circ}\)C/5 h, and the highest in pork loin heated at 57 \({}^{\circ}\)C/3 h (Table 1). It was shown that temperature and time of cooking were factors that significantly influenced the fat content in the examined meat (_p_ < 0.05 and \(p\) < 0.01, resp.). The fat content in the samples decreased with increasing temperature and time of heating. Similar relationships were demonstrated in the studies of [PERSON] et al. [44], and the authors ascribed that change to the melting and leakage of fat from meat samples, which could also be a reason for the fat content change in our study. The small changes in fat content recorded in the present study may be due to the low fat content in pork loin and its even distribution in the muscle structure which limited the fat loss from the meat. In addition, [PERSON] et al. [42] pointed out the presence of volatile organic compounds originated from fatty acids degradation in meat sous vide cooked at 60 \({}^{\circ}\)C, which might have also affected the fat content in samples tested our study. A contrary observation--an increase in fat content after sous vide cooking of poultry compared to raw meat--was noted by [PERSON] et al. [8]. In the study by [PERSON] et al. [45], a reduced fat content after 6 h/60 \({}^{\circ}\)C sous vide cooking of pork compared to raw meat and then mostly higher fat content than in raw meat when cooking took place for 8-18 h at 60 \({}^{\circ}\)C, was reported. It was observed that the protein content in meat after sous vide heat treatment (24.55-27.15%) was higher than in a raw meat (22.89%), with an increase noted with increasing temperature and time of heating (Table 1). Statistical analysis of the results has shown that both above-mentioned cooking parameters were the factors significantly influencing the protein content in the tested meat samples (_p_ < 0.001 and \(p\) < 0.01, resp.). Our results confirm the findings of [PERSON] et al. [8], who reported that the protein content change in poultry, cooked by sous vide, steaming, and boiling, depended on the intensity of the thermal treatment, and those of [PERSON] et al.