## 3 Results and Discussion
### Aroma Recombination and Omission Studies of the Non-Smoked Bacon  
Recombination experiments are commonly used to validate whether key aroma compounds were accurately identified via AEDA and OAV methods [31]. In molecular sensory science, recombination experiments were necessary to accurately simulate the aroma. In this study, the sensory panel discussed the descriptors for the aroma profile of non-smoked Bacon as \"fatty\", \"meaty\", \"sweety\", \"rancid\", and \"grass\". The results of GC-O-MS experiments showed that 12, 9, and 15 volatile compounds had FD factors \(\geq\) 27 in Yunnan, Chongqing, and Sichuan Bacon, respectively. Therefore, the recombination model of each Bacon sample containing these odorants (except for the unknown volatiles) has concentrations that have been calibrated via the external standard method. The data are shown in Table 4, revealing the high linearity of the aroma compounds as indicated by the correlation coefficients (R\({}^{2}\) > 0.99). Figure 4 shows that the aroma profile of the recombination models was similar to their original Bacon sample. Among these five aroma notes, meaty and fatty were dominate. The rancid aroma also played a vital role in Yunnan and Chongqing bacon. Meanwhile, Yunnan Bacon obtained the highest sweety score, which could be attributed to the higher ester content than the other two bacons. The total sensory evaluation scores for five aroma attributes exceeded 75% of the original sample, indicating a good simulation of the aroma characteristics of the Bacon sample. However, the rancid aroma in the recombination model was higher than in the original sample in all three bacons. The excessive addition of aldehydes might be the reason for this result. Omission tests were performed to determine the impact of individual odorants on the overall aroma and to identify active odorants. As shown in Table 5, 12, 9, and 15 volatile compounds in Yunnan, Chongqing, and Sichuan Bacon were selected for omission experiences via the triangulation test. A total of eight, eight, and nine aroma compounds were significantly different from the recombination model after omission in Yunnan, Chongqing,  
Figure 3: Comparison of Venn diagrams for extraction of volatile compounds by GC–O–MS, GC \(\times\) GC–TOFMS, and GC–IMS (**a**); comparison of quantities of various volatile compounds extracted from non-smoked Bacon by GC–O–MS, GC \(\times\) GC–TOFMS, and GC–IMS (**b**). and Sichuan bacon, respectively. These compounds were identified as the key aroma compounds in their respective samples and made a notable impact on the overall aroma. Among these compounds, hexanal, (E,E)-2.4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid were identified as the key aroma compounds shared by all three bacon samples. Meanwhile, 2,3-octanedione, hexanoic acid, and 2-undecenal were considered the key aroma compounds in two bacon samples. For Yunnan and Chongqing bacon, 1-hexanol and (E)-2-nonenal were identified as the key aroma compounds unique to their respective sample. Similarly, octanal and 1-octanol were found to be the key compounds only in the Sichuan bacon sample. Other compounds, including 2,3-butanediol, pentanoic acid, heptanoic acid, nonanal, decanal, heptanal, and 5-ethyldihydro-2(3H)-furanone, had no significant differences in the recombination model after omission. This result suggested that these volatile compounds had little impact on the overall aroma, or their contribution was overshadowed by other compounds. The sensory evaluation results not only validate the identified key aroma compounds but also support the effectiveness of recombination models in accurately simulating the aroma characteristics of bacon samples. Therefore, the key aroma compounds of non-smoked bacon were hexanal, (E,E)-2.4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid. Recombination and omission experiments have been used to identify key aroma compounds and their contents in bacon from different regions.