Impacts of different altitudes and natural drying times on lipolysis, lipid oxidation and flavour profile of traditional Tibetan yak jerky

The impact of different altitudes on the physicochemical properties, lipolysis, lipid oxidation, volatile compound formation and sensory evaluation of traditional Tibetan dried yak jerky during natural drying was investigated. High altitude (HA) yak jerky showed higher percentages of unsaturated fatty acids and thiobarbituric acid reactive substances than low altitude (LA) yak jerky during natural drying (P < 0.05). The percentages of polyunsaturated fatty acids and monounsaturated fatty acids decreased during natural drying, whereas that of saturated fatty acids increased (P < 0.05). A total of 54 volatile compounds were identified and quantified, and there were higher contents of volatile compounds in HA yak jerky than in LA jerky, which were mainly derived from lipid oxidation. Principal component analysis showed that the volatile compounds associated with the highest overall acceptability in HA yak jerky were hexanal, nonanal, (E)-2-nonenal, 1-hexanol, 2-heptanone, 2-methy1-3-octanone and 6-methyl-5-hepten-2-one. The volatile compounds associated with the highest overall acceptability for yak jerky with a longer natural drying time were hexane, 1-octanol, 2-ethylhexanol, heptanal, (E)-2-hexenal, (E)-2-octenal, 1-octen-3-ol and 2,3-octanedione. According to the sensory evaluations, HA yak jerky with a natural drying time of 75 d tends to be more popular.