The significance of Shewanella sp. strain HSO12, Photobacterium phosphoreum strain HS254 and packaging gas composition in quality deterioration of fresh saithe fillets

Abstract This study presents the significance of Shewanella sp. strain HS012 and Photobacterium phosphoreum strain HS254 and the packaging gas composition (67% CO2 balanced with either O2 or N2) related to fillet freshness, microbiological spoilage, and physiochemical parameters of portioned inoculated saithe fillets (Pollachius virens). Saithe fillets packaged in CO2/N2 gave, independent of inoculum, faster conversion of inosine (HxR) to hypoxanthine (Hx), and thereby increased fillet spoilage (increased H-value), faster increase in dimethyl amine (DMA) and trimethyl amine (TMA) content, the highest level of the tyrosine (Tyr), and the lowest level of lactate. Moreover, it was found that independent of initial microbiota and packaging gas composition, the main bacterial genera after 14 days of cold storage was P. phosphoreum. Among samples packaged in CO2/N2, the highest Hx and TMA content and the highest H-value were observed in samples inoculated with P. phosphoreum. Moreover, among fillets packaged in CO2/O2, samples inoculated with P. phosphoreum or a mix of both Shewanella sp. and P. phosphoreum (50:50) tended to have the highest H-value and the highest Hx and TMA levels. No clear evidence was found related to spoilage microbiota's impact on physiochemical parameters such as fillet drip loss or firmness.