## 3 Results and Discussion
### Volatile Compounds
The PT15 sample included three aldehydes (hexanal, nonanal and decanal), two alcohols (1-octen-3-ol and (E)-2-octen-1-ol), 2-ethyl-3,5-dimethylpyrazine, and 3-hydroxy-2-butanone. The PT30 sample contained various volatile compounds (OAVs \(>\) 1) that were in the CT sample, except (E,E)-2.4-decadienal. The PT45 sample included four aldehydes (hexanal, octanal, nonanal, and decanal), three alcohols (1-octen-3-ol, (E)-2-octen-1-ol, and propyl disulfide), 3-hydroxy-2-butanone, and 2-ethyl-3,5-dimethylpyrazine. Similarly, [PERSON] et al. [14] found that the formation of volatile compounds in dried pork loin was affected when plasma-treated water was used in the marinating process. Compared with the CT samples, the content of hexanal significantly (\(p<0.05\)) decreased in the plasma-treated samples, and none was detected in the nitrite-treated samples. This result is consistent with the TBARS result, since hexanal is usually produced by linoleic acid oxidation [35]. In addition, it has been reported that the formation of hexanal can be inhibited by nitrite curing in meat products such as dry fermented sausages [35; 36]. Similarly, the contents of nonanal in the PT and NT samples were significantly (\(p<0.05\)) lower than those of the CT samples. [PERSON] et al. [14] also reported that the nonanal concentration of Chinese dried pork loin marinated with untreated brine was higher than that of pork loin marinated with plasma-treated water. In addition, compared with CT samples, the content of heptanal, octanal, (E)-2-octenal, decanal, and (E)-2-nonenal decreased by 56.09%, 47.94%, 57.24%, 11.19%, and 49.25%, respectively, in the PT30 samples, while these aldehydes were not detected in the NT, PT15, and PT45 samples. (E,E)-2,4-Decadienal was not detected in the PT and NT samples. As we know, the formation of aldehyde compounds is related to the protein degradation and lipid oxidation during the processing of roasted meat [35]. The decrease of such aldehydes in roasted lamb treated with plasma and nitrite might be the result of the decrease in lipid oxidation during processing. The contents of hexanal, nonanal, heptanal, octanal, E-2-octenal, decanal, and(E)-2-nonenal in the PT samples were higher than those of the NT samples. [PERSON] et al. [37] also found that total aldehydes in fermented sausages with 80 mg/kg nitrite and 95 mg/kg nitrate obviously decreased compared with those with 150 mg/kg nitrite and 178 mg/kg nitrate. Compared with CT samples, the propyl disulfide content significantly (\(p<0.05\)) increased in the PT30 and NT samples, while the contents of E-2-octen-1-ol, and 1-octen-3-ol significantly (\(p<0.05\)) decreased. 1-Octen-3-ol, with a mushroom flavour, is usually generated from linoleic acid \(\beta\)-oxidation [14; 37]. In this study, the inhibition of lipid oxidation caused by plasma treatment gave rise to a reduction of 1-octen-3-ol compared with the CT samples. Similarly, the content of 1-octen-3-ol of the PT samples was higher than that of the NT samples. The reason might be the fact that the inhibitory rate of lipid oxidation in the plasma treatment was significantly (\(p<0.05\)) lower compared with the nitrite treatment. The content of 3-hydroxy-2-butanone in the CT sample was significantly (\(p<0.05\)) higher than that of the NT, PT30, and PT45 treatments, but there was no significant (\(p>0.05\)) difference in samples between CT and PT15 treatments. 3-Hydroxy-2-butanone is mainly derived from carbohydrate fermentation [37]. [PERSON] et al. [17] showed that plasma treatment can inhibit the microbial growth in pork jerky during processing, so long-term plasma treatment in PT30 and PT45 might inhibit microbial growth related to the generation of 3-hydroxy-2-butanone. 2-Ethyl-3,5-dimethylpyrazine, as one of the pyrazine compounds, might be related to the roasted flavour in roasted lamb. There were no significant (\(p>0.05\)) differences in the content of 2-ethyl-3,5-dimethylpyrazine in roastedlamb among all treatments. [PERSON] et al.