Quality assessment of ice-stored tropical yellowfin tuna (Thunnus albacares) and influence of vacuum and modified atmosphere packaging.

Metagenomic, microbial, chemical and sensory analyses of Thunnus albacares from Martinique stored in ice (AIR - 0 °C), vacuum (VP - 4/8 °C) and modified atmosphere packaging (MAP - 4/8 °C) (70% CO2 - 30% O2) were carried out. The organoleptic rejection of AIR tuna was observed at day 13 when total bacterial counts equaled 10(6)-10(7) CFU g(-1). No extension of shelf-life was provided by VP and MAP. According to 16S rRNA gene sequence analyzed by Illumina MiSeq and PCR-TTGE, Rhodanobacter terrae was the main species of the freshly caught tuna. At the sensory rejection time, Brochothrix thermosphacta and Pseudomonas dominated the AIR products while B. thermosphacta alone or a mix of B. thermosphacta, Enterobacteriaceae and lactic acid bacteria (LAB) dominated the microbiota of MAP and VP products, respectively. The pH value remained stable in all trials, ranging from 5.77 to 5.97. Total volatile basic nitrogen (TVBN) and trimethylamine (TMA-N) concentrations were weak and not significantly different between batches. Lipid oxidation increased in the samples containing O2 (MAP > AIR). The initial concentration of histamine was high (75-78 mg kg(-1)) and stable up to 8 days but then significantly decreased in all trials to reach 25-30 mg kg(-1), probably due to the presence of histamine-decomposing bacteria.
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