• Ultrasonic-assisted curing on the flavor formation of Chinese bacon was feasible. • PC and PE were the main flavor precursors in the curing process. • A total of 28 volatile compounds were detected by GC–MS. • The activity of phospholipase is highest during the curing process.

Chinese bacon is highly esteemed by consumers worldwide due to its unique aroma. The composition of volatile organic compounds (VOCs) varies significantly among different types of Chinese bacon. This study analyzed the VOCs of Chinese bacon from Sichuan, Hunan, Guangxi, and Shaanxi provinces using gas chromatography-mass spectrometry (GC-MS), an electronic nose (E-nose), and gas chromatography-ion mobility spectrometry (GC-IMS). The results demonstrate that the combination of GC-MS and GC-IMS effectively distinguishes Chinese bacon from different regions. Notably, Guangxi bacon lacks a smoky aroma, which sets it apart from the other types. However, it contains many esters that play a crucial role in its flavor profile. In contrast, phenols, including guaiacol, which is typical in smoked bacon, were present in the bacon from Sichuan, Hunan, and Shaanxi but were absent in Guangxi bacon. Furthermore, Hunan bacon exhibited a higher aldehyde content than Sichuan bacon. 2-methyl-propanol and 3-methyl-butanol were identified as characteristic flavor compounds of Zhenba bacon. This study provides a theoretical foundation for understanding and identifying the flavor profiles of Chinese bacon. Using various analytical techniques to investigate the flavor compounds is essential for effectively distinguishing bacon from different regions.

To elucidate the relationships between lipid components and odor traits, this study comparatively characterized the distinct lipid compositions and flavor volatiles in giant salamander tails of different sexes via mass-spectrometry-based lipidomics and GC-IMS. A total of 3145 fat metabolites were detected in male and female giant salamander tails, with the largest contributors being triglycerides (TGs, 840) and phosphatidylcholines (PCs, 383). Notably, the contents of PCs and TGs were greater in female tails than in male tails, and the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also greater in the female group. Additionally, a total of 45 volatile components were detected, namely, 14 aldehydes, 14 alcohols, 9 ketones, 3 acids, 3 esters, 1 ether, and 1 amine. Alcohols (29.96% to 34.85%) and aldehydes (21.07% to 22.75%) were the predominant volatiles. Multivariate statistical analysis revealed 22 key differential fats and 26 differential odor substances as distinguishing labels between sexes. Correlation analysis revealed that the concentrations of triethylamine, dimethyl sulfide, ethanol-D, and 3-methyl butanal-D were significantly positively correlated with the concentrations of diglyceride (DG) (26:6e), cardiolipin (CL) (59:4), acylcarnitine (AcCa) (22:4), and triglyceride (TG) (52:10) (p < 0.01). Threefold cross-validation revealed that the prediction accuracies of these differential lipids and volatile compounds for sex recognition via the random forest model were 100%. These findings might not only provide insight into the effects of sexes on the lipid and volatile profiles of giant salamander tails but also provide clues for their gender recognition.

Traditional bacon processing involves marked lipid remodeling, yet the stage-dependent dynamics of individual lipid species remain unclear. In this study, fatty acid analysis, UPLC-MS/MS-based untargeted lipidomics, and interpretable machine learning were integrated to characterize lipid transitions during Zhenba bacon processing. Polyunsaturated fatty acids, especially linoleic acid, increased significantly during curing, suggesting pronounced lipid mobilization at this stage. Untargeted lipidomics identified 34 core differential lipids associated with processing-stage discrimination. K-means clustering revealed three temporal patterns: continuous decline, peak at curing, and continuous accumulation. Some structural phospholipids and triglycerides decreased progressively, whereas several complex lipids accumulated during late processing. AdaBoost–SHAP further identified TG(60:8) and PS(47:2) as representative lipid features contributing strongly to stage classification. These findings demonstrate that lipid remodeling during Zhenba bacon processing is highly stage-dependent and non-linear, and provide a lipid-based basis for process monitoring and quality evaluation.