Real time and non-destructive quantification of volatile organic compounds associated with spoilage bacteria in packed blue mussels (Mytilus edulis) using SIFT-MS.

Psychromonas arctica, Shewanella frigidimarina, and Pseudoalteromonas elyakovii have been identified and characterized as major spoilage bacteria in packed blue mussels (Mytilus edulis). This study aimed to analyze spoilage bacterial growth and to characterize the specific metabolic products of these spoilage bacteria. For this purpose, bacterial solutions were transferred onto irradiated mussel substrates and exposed to air or modified atmospheres (MAs) with the following compositions of (%CO2/O2/N2): (40/60/0) and (25/75/0). These packages were stored at 4 °C for 15 days, with quality monitoring of the headspace composition (% CO2/O2), pH, microbial analysis, and volatile organic compounds (VOCs) production. Selected-ion flow-tube mass spectrometry (SIFT-MS) was employed to monitor the evolution of VOCs over time. The findings reveal that when cultivated in irradiated mussel substrates and packaged under MAs, the populations of Psy. arctica, S. frigidimarina and Pseu. elyakovii exhibited limited growth with maximum levels of 6.1 ± 0.1 log CFU.g-1 along with limited production of VOCs. Conversely, under air packaging, bacterial proliferation exceeding 7 log CFU.g-1 was associated with the emission of unique VOCs. High production levels of dimethyl sulfide (1000-3280 ppbv) were attributed to S. frigidimarina, while Pseu. elyakovii multiplication led to high emissions of hydrogen sulfide (520-3840 ppbv) and methyl mercaptan (1680-6300 ppbv). The increase in ethanol levels (1150-7930 ppbv) was linked to Psy. arctica. Investigating VOCs in irradiated mussel substrates is significant for understanding bacterial metabolism suggesting their potential as spoilage-specific organisms.