## 2 Materials and Methods
### Roasted Lamb Processing  
Twenty-five raw _silversides_ from the left side of small male fat-tail sheep (same genetic background) were purchased from Grassland Hongbao Food Co., Ltd. (Inner Mongolia, China). The sheep were fed in confinement with a commercial diet (same feeding system) and, at 24.90 \(\pm\) 0.55 kg live weight (approximately 7 months old), were stunned, slaughtered, and exsanguinated at a local slaughterhouse on the batch. Twenty-four hours post-mortem at 95% humidity and 4 \({}^{\circ}\)C, the ultimate pH in the _silversides_ was 5.65 \(\pm\) 0.03, and these _silversides_ were then frozen at \(-\)30 \({}^{\circ}\)C. All _silversides_ were vacuum packed and transported to our lab by cold-chain logistics and stored at \(-\)30 \({}^{\circ}\)C until used. The 25 _silversides_ with the same genetic background and the same feeding system were consistent in biological information. The 25 _silversides_ were randomly divided into five groups (fivesilversides_ in each group): CT (without sodium nitrite and plasma treatment), NT (with nitrite treatment), PT15 (without nitrite and with 15 min plasma treatment), PT30 (without nitrite and with 30 min plasma treatment), and PT45 (without nitrite and with 45 min plasma treatment). Each _silverside_ was cut into 15 cubes of 3 cm \(\times\) 3 cm \(\times\) 1.5 cm (75 cubes in each group). Subsequently, each group was equally divided into three batches (25 cubes in each batch), in which the cubes from each batch represent one replicate sample, and the cubes from those three batches were cured independently: a total of 3 replicates were performed. The cubes in each batch from the five groups were cured according to Table 1. Briefly, the cubes from the first group were cured with 1% salt, 10% onion, and 3.5% egg white (without sodium nitrite and plasma, CT). The second group was cured with 1% salt, 10% onion, 3.5% egg white, and 0.005% sodium nitrite (NT). Another three groups were cured with 1% salt, 10% onion, and 3.5% egg white and subsequently treated by plasma for 15 min, 30 min, and 45 min, respectively (PT15, PT30, and PT45). These additives (salt, onion, egg white, and sodium nitrite) were added according to the weight of the meat, and curing was carried out at 4 \(\pm\) 1 \({}^{\circ}\)C for 2 h. The atmospheric nonthermal plasma device was equipped with a dielectric-barrier discharge plasma system (DBD, SY-JXW-02, Suzhou FYB Agricultural Science and Technology Co., Ltd., Jiangsu, China), and it included a chamber for placing cured samples and a tube for transferring and cooling plasma gas. In this study, the plasma was discharged at a power of 40 W and a frequency of 10 kHz, and the flow rate of ambient air used as the process gas was 20 L/min. In addition, during plasma treatment, the temperature of the chamber was 0-5 \({}^{\circ}\)C.  
After curing and plasma treatment, all the samples were roasted using an electric roasting oven (SJD-305-16, Xingguanyang Technology Co., Ltd., Wuxi, China). The temperature of the electric roasting oven was about 400-450 \({}^{\circ}\)C and lasted for 7 min, and the sample was turned over once per minute. For each batch in the same treatment group, 12 roasted cubes were immediately used for sensory evaluation after roasting, 4 roasted cubes were used for the detection of residual sodium nitrite, thiobarbituric acid value (TBARS value), and sulfhydryl content; 6 roasted cubes were used for the measurement of colour and shear force value; and 3 roasted cubes were used for the analysis of volatile compounds.