## 4 Conclusions  
In this study, GC-O-MS, GC \(\times\) GC-TOFMS, and GC-IMS were simultaneously employed to analyze and identify odor-active compounds in non-smoked bacon. Among three bacon samples, 239 volatiles were identified, and 74, 188, and 72 volatiles were detected via GC-O-MS, GC \(\times\) GC-TOFMS, and GC-IMS, respectively. GC \(\times\) GC-TOFMS and GC-IMS could provide high resolution and trace detection capabilities but could not be combined with human senses. GC-O-MS improved this defect and had more advantages in the quantification of volatiles. After recombination and omission tests, hexanal, (E,E)-2,4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid were considered the key aroma compounds in non-smoked bacon. Seven volatiles were considered contributors in the formation of aromas from different regions, including 2,3-octanedione, hexanoic acid, 2-undecenal, 1-hexanol, (E)-2-nonenal, octanal, and 1-octanol. Instead of the type, the content of volatiles was the primary factor affecting the aroma of non-smoked bacon from Yunnan, Sichuan, and Chongqing bacon. These findings can provide valuable molecular information for enhancing aroma quality, assessing product quality, and distinguishing non-smoked bacon by geographic origin. Future studies could investigate the impact of important steps in bacon aroma formation on key aroma compounds.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/foods13081260/s1](https://www.mdpi.com/article/10.3390/foods13081260/s1)]([https://www.mdpi.com/article/10.3390/foods13081260/s1](https://www.mdpi.com/article/10.3390/foods13081260/s1)), Table S1: Volatile compounds in non-smoked bacon detected by GC \(\times\) GC-TOFMS.  
H.W.: conceptualization, data curation, and writing--original draft. Z.H.: methodology. L.Y.: investigation and formal analysis. H.L.: supervision. All authors have read and agreed to the published version of the manuscript.  
This work was funded by Chongqing Technology Innovation and Application Development Special Key Project (Grant No. CSTB2022 TIAD-KPX0300), Collaborative innovation and key technology of rabbit industry in Sichuan and Chongqing (Grant No. 2022 YFG0033), and China Agriculture Research System of MOF and MARA (Grant No. CARS-43-E-2).  
Ethical review and approval were waived for this study due to (1) the health food used for the study does not contain additives; (2) the food additives contained in the food used for the study are within the safety range and do not exceed the standards of the relevant national departments, or the content of chemical pesticides or environmental pollutants does not exceed the standards of the relevant national departments safety range. The bacon samples utilized in this study were qualified products, and the evaluators did not experience any health effects from sniffing their odors. All evaluators were informed of and consented to this study.  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The original contributions presented in the study are included in the article/Supplementary Materials, further inquiries can be directed to the corresponding author.  
We thank [PERSON] for assistance with GC-MS measurements.  
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.