A Time-Resolved PTR-ToF-MS Workflow for Characterizing Opening-Burst Volatile Features in Canned Antarctic Krill Under Equivalent F0 Processing

Volatile release immediately after opening canned foods is highly transient and may not be adequately represented by equilibrium or quasi-equilibrium headspace measurements. In this study, time-resolved proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) was used to characterize opening-burst volatile features in canned Antarctic krill processed to an equivalent sterilization intensity (F0 ≈ 9 min). Raw krill, pretreated but non-retorted samples, and samples retorted using different temperature–time combinations were monitored online for 180 s after opening, with particular attention to the 0–60 s burst phase. Twenty-three of the twenty-five retained features reached their maximum responses within 10 s, including two within 5 s, showing that the dominant volatile changes occurred immediately after opening. The maximum background-corrected response during 0–60 s (Cmax,0–60) and the corresponding area under the response curve (AUC0–60) were used to describe transient release. The nine highest-ranked features accounted for 76.78% of the cumulative AUC0–60 response within the retained candidate feature set. Although the retort treatments had similar F0 values, their burst-phase fingerprints remained distinguishable. Sulfur-associated features varied markedly among treatments, whereas several low-molecular oxygenated features showed strong responses after the 121 °C high-temperature/short-time treatment. These findings show that the first seconds after opening contain substantial volatile-release information and that equivalent sterilization lethality does not necessarily produce the same opening-burst fingerprint. Time-resolved PTR-ToF-MS therefore enables direct examination of the initial post-opening volatile environment and comparison of different thermal processing routes. Chemical names are reported as putative annotations rather than definitive identifications.