Volatile compounds associated with <i>Psychrobacter</i> spp. and <i>Pseudoalteromonas</i> spp., the dominant microbiota of brown shrimp (<i>Crangon crangon</i>) during aerobic storage

Psychrobacter and Pseudoalteromonas species dominate the microbiota of cooked brown shrimp (Crangon crangon). Therefore, the spoilage potential of several Psychrobacter and Pseudoalteromonas species (Psychrobacter cibarius, Psychrobacter maritimus, Pseudoalteromonas elyakovii, Pseudoalteromonas paragorgicola and Pseudoalteromonas nigrifaciens) was determined and quantified based on the presence of VOCs. Additionally, API ZYM analyses determined the species’ enzymatic capacity to contribute to spoilage by degrading lipids, amino acids and proteins. The bacterial species used in this study were isolated from cooked brown shrimp during storage (spoilage) under different storage and processing (peeled, unpeeled) conditions and were selected for analysis of their spoilage potential based on their difference in the (GTG)5-rep profile, 16S rRNA and gyrB sequences and API ZYM profile. The isolates were inoculated as pure cultures on heat-sterilised shrimp. The inoculated samples were stored at 4°C and the production of VOCs by the pure strains on the shrimp matrix was identified via gas chromatography coupled to mass spectrometry (GC-MS). VOC production was quantified daily by selected ion flow tube mass spectrometry (SIFT-MS) until the bacterial count exceeded 108 - 109 cfu/g. Based on the API ZYM results, Pseudoalteromonas as well as PsychrobacterPsychrobacter species revealed very low potential of the production of VOCs. Pseudoalteromonas species, especially Pseudoalteromonas elyakovii and Pseudoalteromonas nigrifaciens, produced significant amounts of volatile compounds such as sulphides, acetone, ammonia, and ethanol, which are all involved in seafood spoilage, and might be responsible for the off-odours produced during spoilage of brown shrimp