# Quality of Sous Vide-Cooked Pork Loin Stored in Refrigerated Conditions
## 3 Results and Discussion
### Instrumental Texture Analysis
#### 3.3.2 Texture Profile Analysis (TPA)  
It was observed that at the beginning of the storage study, regardless of the heat treatment parameters, pork loin samples did not differ significantly in terms of hardness assessed on the basis of the TPA test (34.71-44.41 N). Although the increasing hardness values were noted for all treatments with prolonged time of storage, only the sample heated at 61 \({}^{\circ}\)C/4 h on day 7 of storage showed significantly higher hardness than the samples heated at 60 \({}^{\circ}\)C/4 h and 63 \({}^{\circ}\)C/3.5 h immediately after heat treatment. There were no significant differences in hardness between the remaining samples during the entire storage period, but in general, the highest hardness values were determined for the sample cooked at 61 \({}^{\circ}\)C/4 h. The statistical analysis showed that the hardness of stored pork loin was significantly affected by the treatment parameters (\(p<0.05\)) and time of storage (\(p<0.001\)), but not their interaction. We hypothesise that the increase in hardness may be related to several factors, including changes in muscle proteins and subsequent water loss from meat, which were also pointed out by [PERSON] et al. [23], as a probable reason for the increase in shear force of chicken breast sous vide cooked and stored in refrigerated conditions for 14 days. In the study by [PERSON] et al. [3], reduced hardness of sous vide-cooked beef compared to the control sample cooked in a water bath was noted. [PERSON] et al. [64] investigated the effect of different temperature-time combinations of sous vide cooking on duck breast meat quality and found that lower temperatures and shorter times of cooking resulted in increased tenderness of the meat, while [PERSON] et al. [65], who studied sensory properties of sous vide-cooked beef, reported increased tenderness when meat was cooked at lower temperatures for longer times. Regarding springiness of stored samples, it tended to decline during storage for all samples, but only minor differences between samples were observed (0.44-0.50), with the only significant one between the sample cooked at 57 \({}^{\circ}\)C/5.5 h on day 3 of storage and the sample cooked at 60 \({}^{\circ}\)C/4 h on day 0 of storage. Like hardness, springiness was significantly affected by the treatment parameters and the time of storage (both p \(<0.01\)), but not their interaction. Changes in meat cohesiveness were also minor during storage and the values were in the range 0.44-0.57. The highest values during storage were noted for meat cooked at 60 \({}^{\circ}\)C/4 h, and the lowest for meat cooked at 63 \({}^{\circ}\)C/3.5 h. Significant changes in cohesiveness during storage were observed only for samples cooked at 61 \({}^{\circ}\)C/4 h and 63 \({}^{\circ}\)C/3.5 h. Regarding the chewiness of stored pork loin, the increasing tendency was observed with prolonged storage time, but that increase was significant only for samples cooked at 60 \({}^{\circ}\)C/4 h and 61 \({}^{\circ}\)C/4 h. Cohesiveness and chewiness were significantly affected by treatment and storage time (both \(p<0.001\)) and chewiness was also affected by their interaction (\(p<0.001\)).  
There are few studies described in the literature on the quality of meat heated using the sous vide method and then stored and, particularly, few studies provide information on the texture of such meat. Nevertheless, [PERSON] et al. [22] did not find significant differences between the hardness, cohesiveness, gumminess, and chewiness of the sous vide-cooked pork loin samples during 0, 5, and 10 weeks of storage; however, they observed a significant decline in springiness of samples with prolonged time of storage. The authors pointed out a discrepancy between the results of shear force test and TPA hardness. The changes in meat texture during storage was ascribed to protein degradation.