# Quality of Sous Vide-Cooked Pork Loin Stored in Refrigerated Conditions
## 3 Results and Discussion
### Volatile Compounds
[29], a total of 94 compounds were identified in fermented pork, including ketones (10), acids (8), alcohols (19), aldehydes(15), esters (27), and other compounds (10), while in the experiment of [PERSON] et al. [68], a total of 93 compounds were identified in Tibetan pork, raw or cooked with the use of different heat treatment methods, including 10 esters, 22 aldehydes, 16 alcohols, 8 ketones, 24 aliphatic hydrocarbons, 3 phenols, and 10 other compounds. [PERSON] et al. [16] noted the presence of more than 100 volatile compounds in pork cheeks, sous vide cooked with the use of different combinations of temperature-time of cooking conditions and vacuum level in the package. [PERSON] et al. [12] found 11 volatile compounds in raw lamb loin, and 57 volatiles in cooked meat, and these were aldehydes, aliphatic and aromatic hydrocarbons, ketones, alcohols, esters, furans, and sulfur compounds. [PERSON] and [PERSON] [69] reported an increase in volatile compounds and lipid oxidation with increased cooking temperature of foal meat and found that the main volatile compounds in raw meat were esters, while in cooked meat, the main volatiles were aldehydes. [PERSON] et al. [68] observed that more intense lipid oxidation in sample led to the higher content of volatile compounds and enriched types of volatiles after heat treatment of pork, suggesting that such treatment may promote the degradation of lipids and proteins and enrich the diversity of volatile flavour compounds in pork. [PERSON] et al. [12] concluded that volatile compounds derived from lipid oxidation dominated in lamb loin subjected to milder sous vide cooking conditions, namely, 60 \({}^{\circ}\)C for 6 or 24 h, 80 \({}^{\circ}\)C for 6 h, whereas the presence of volatiles from Strecker degradation was more pronounced when meat was cooked at 80 \({}^{\circ}\)C for 24 h. A reduction in the concentration of some volatile compounds generated in lipid oxidation, when the cooking time of pork cheeks at 80 \({}^{\circ}\)C was increased from 5 to 12 h, was reported by [PERSON] et al. [16]. In order to characterise the profile of volatile compounds in pork and identify potential volatile markers related to the heating of pork, principal component analysis (PCA) was used. The visualisation of the PCA biplot (Figure 3), for which the first two principal components (PC) explained 56% of the data variability, showed that meat, depending  
Figure 2: Meat sample fingerprints after incubation at 50 \({}^{\circ}\)C.  
on thermal processing, can be identified and distinguished from others based on the thermal processing temperature. PCA analysis based on the signal intensity of detected volatile compounds showed effective differentiation of samples from different stages into relatively independent spaces. Along PC1, a distinction has been shown from the thermal processing temperature, so raw meat is clearly separated from thermally processed meat, supporting the notion that temperature plays a major role in altering the volatile compound composition. However, the sample processed at 57 \({}^{\circ}\)C/0 days showed overlap with other thermally processed samples. This indicates that while temperature drives differentiation to a large extent, some cases display similar volatile profiles, possibly due to limited variability in the data or subtle differences not captured by the first two principal components. Along PC2 in the PCA biplot, the analysis provided additional variation in volatile compound profiles, but this time, likely due to secondary factors beyond cooking temperature. PC2 accounted for 28% of the variability and could highlight differences in specific compounds or reaction products that appear at similar temperatures but vary due to other conditions such as cooking time or specific chemical interactions. For example, some compounds, such as 2,3-hexanedione and trimethylamine, are more distributed along PC2, suggesting that they play a distinct role in defining the aroma profile at different stages of thermal processing, which are not solely determined by temperature.