Closed-loop VOC profiling as a proof-of-concept screening approach for pathogen activity in liquid egg and ground beef

Rapid, non-invasive screening technologies capable of detecting early microbial activity in high-risk foods are needed to support food safety monitoring and process control. This study presents a proof-of-concept evaluation of a closed-loop volatile organic compound (VOC) collection system coupled with gas chromatography-mass spectrometry (GC-MS) to determine whether pathogen growth generates reproducible, matrix-dependent VOC signatures in real food systems. Two application-relevant case studies were investigated: (1) Salmonella Enteritidis in liquid whole egg and (2) Escherichia coli O157:H7 in ground beef, representing protein- and lipid-rich matrices of high regulatory and industrial importance. Food samples were inoculated under controlled conditions, incubated for 6 h, and compared with uninoculated controls to isolate VOCs associated with pathogen metabolism rather than background food volatiles. In liquid egg, multiple nitrogen- and oxygen-containing VOCs were consistently detected only in S. Enteritidis -inoculated samples, reflecting early utilization of protein-derived substrates. In ground beef, distinct lipid- and amino acid-derived VOCs emerged reproducibly in E. coli O157:H7 treatments, consistent with microbial metabolism of fatty acids and muscle proteins. Analytical robustness was evaluated using biological replication, presence-absence consistency, fold-change assessment, and strict background subtraction to exclude instrument- and environment-related artifacts. The results demonstrate that closed-loop VOC profiling can differentiate pathogen-inoculated foods from controls within short incubation periods and that VOC patterns are strongly governed by food matrix chemistry. While limited to representative pathogen-matrix pairs, this application-oriented study establishes technical feasibility and provides a foundation for developing VOC-based screening tools for rapid pathogen detection in high-risk food commodities.