services and food processing to provide foods of superior sensory quality with a longer shelf-life as compared to those cooked using conventional cook-chill technologies [1,2]. The sous-vide cooking conditions used by chefs for different types of meat are very different to those used for traditional cooking methods or in catering. Thus, commonly recommended combinations of temperature and time by chefs for beef, pork or lamb are around 58-63 \({}^{\circ}\)C for 10-48 h, while temperatures for pork in catering most likely reaches 75-80 \({}^{\circ}\)C [1]. Only in the last years, a few studies have considered the effects of sous-vide cooking at low temperature for long periods on the physico-chemical changes undergone by meat [3, 4, 5], but the scientific information available on its effect on the development of cooked meat flavor is scarce.  
It is well accepted that raw meat has little or no aroma and a blood-like taste, and that the flavor of cooked meat is thermally developed during cooking, mainly from amino acids and lipids [6]. Quantitatively, lipid oxidation is the major source of volatile compounds in cooked meat, specially the oxidation of unsaturated fatty acids [7]. On the other hand, Strecker degradation of amino acids and Maillard reactions produce a considerable number of branched and heterocyclic volatile compounds with low odor thresholds, which seem to be the main responsibles for the meaty flavor [6,7]. Finally, thiamine degradation generates a series of sulphur-containing compounds with characteristic meaty flavor, such as 2-methyl-3-furanthiol [7,8].  
The profile of volatile flavor compounds of cooked meat is strongly affected by the characteristics of the cooking process. Different cooking procedures comprise a wide range of temperatures, from 50 \({}^{\circ}\)C in the center of a grilled rare steak, to around 200 \({}^{\circ}\)C in its exterior or in the surface of oven-roasted meat, or a constant temperature of around 100 \({}^{\circ}\)C during meat stewing. Not only the temperature but also the cooking time and the extent of meat dehydration (_i.e._, much more intense in the surface of roasted meat than in the stewed meat) are dependent upon the type of cooking [6]. These different cooking conditions affect the type and extent of the chemical reactions leading to the formation of flavor compounds. For example, high temperatures and dehydration enhance Maillard reactions [6], and lipid degradation leads on to different volatile compounds at high temperatures (thermal lipid oxidation) or at moderate to low ones (lipid autoxidation) [7]. Although many studies since the 1950s have focused on the profile of volatile compounds of meat cooked following traditional methods, very scarce scientific information is available on the formation of volatile compounds in sous-vide cooked meat at low temperature and for long times.  
It seems clear that the absence of oxygen achieved through vacuum packaging leads to a lower extent of lipid oxidation during the storage of cooked meat and meat products [9]. However, there is not much information about how would it affect the development of the chemical reactions leading to the development of cooked meat flavor during cooking. Previous studies showed lower amounts of hexanal and total amount of volatile compounds in cooked and irradiated vacuum-packaged pork patties as compared to aerobic-packaged ones [10], but no information about the effect of vacuum on the volatile profile of sous-vide cooked meat at low to moderate temperatures is available in the scientific literature. Thus, the purpose of this work was to study the effects of vacuum, cooking temperature and cooking time on the volatile compounds profile of sous-vide cooked pork cheeks.