Identification of dynamic changes in volatile compounds and metabolites during the smoking process of Zhenba bacon by GC-IMS combined metabolomics

Zhenba bacon is a traditional cured bacon product with a rich history that originated from Zhenba County, Shaanxi Province. This study aimed to investigate the patterns of volatile compound formation and changes in metabolites during the smoking process in Zhenba bacon. Firstly, the sensory properties and physicochemical properties of Zhenba bacon were analyzed. Gas chromatography-ion mobility spectrometry (GC-IMS) and nontargeted metabolomics technology were used to analyze Zhenba bacon from different smoking stages. The results show a gradual increase in the sensory acceptance and volatile flavor compounds such as aldehydes, ketones, and esters with the prolongation of smoking of Zhenba bacon. LC-MS analysis identified 191 co-expressed differentially metabolites, with amino acid and lipid metabolism being the main metabolic pathways according to KEGG enrichment analysis. Temporal expression analysis of bacon metabolites at each stage revealed a decrease in harmful steroid hormones such as cortisone and an increase in amino acids and lipid metabolites, such as arginine, lysine, acid, and cholesterol, that contribute to the flavor of bacon. In summary, duration of smoking increased, the amount of flavor substances in Zhenba bacon gradually increased, and the safety and quality of bacon reached the optimal level after 32 days of smoking. This study provides valuable insights into the dynamic changes in volatile flavor compounds in Zhenba bacon and establishes a theoretical foundation for quality control during its production.