Identification of the Volatile Compounds Produced in Sterile Fish Muscle (Sebastes melanops) by Pseudomonas fragi1

Abstract

Volatile compounds produced by Pseudomonas fragi strain 18 in sterile fish muscle (Sebastes melanops) were identified by combined gas-liquid chromatography and mass spectrometry. Compounds positively identified included dimethyl sulfide, acetaldehyde, ethyl acetate, ethyl alcohol, and dimethyl disulfide. Methyl mercaptan, ethyl butyrate, ethyl hexanoate, and butanone were tentatively identified by relative retention times of the authentic compounds. The fruity odor that developed in fish muscle during incipient spoilage was attributed to a synergistic flavor interaction involving the ethyl esters of acetate, butyrate, and hexanoate.

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

“…Initially, a majority (93%) of gram-negative bacteria was (Hovda et al, 2007b;Jaffrès et al, 2009;Kakouri and Nychas, 1994;Koutsoumanis and Nychas, 1999;Mamlouk et al, 2012;Mejlholm et al, 2005;Nychas et al, 2008) or in lightly preserved VP products (Olofsson et al, 2007), but more rarely from fish stored under air (Noseda et al, 2012). On the contrary, Pseudomonas spp., particularly P. fragi, is often reported to be responsible for sweet and fruity off-odors in fish flesh stored under air (Gennari et al, 1999;Gram and Huss, 1996;Hovda et al, 2007a;Hozbor et al, 2006;Koutsoumanis and Nychas, 1999;Miller et al, 1973;Ola and Oladipo, 2004;Parlapani et al, 2015a;Parlapani et al, 2015b;Parlapani and Boziaris, 2016;Ravi Sankar et al, 2008). In agreement with previous studies (Lalitha et al, 2005;Lopez-Galvez et al, 1995;Özogul et al, 2004;Ravi Sankar et al, 2008), CO 2 has a bacteriostatic effect which delays the growth of various flora, and Pseudomonas are particularly sensitive to CO 2 (Ehsani and Jasour, 2012;Koutsoumanis et al, 2000).…”

Molecular Taxonomic Profiling of Bacterial Communities in a Gilthead Seabream (Sparus aurata) Hatchery

“…For instance, two Pseudomonas OTUs (705 and 1953) contribute to the quite high abundance of this genus in mature fish larvae. They display close phylogenetic relationship with P. fragi (Miller et al, 1973 ; Cormier et al, 1991 ) and P. lini (Delorme et al, 2002 ), respectively, and extremely low abundances in live feed samples (Table S1 ). Although the life-strategy of P. fragi and relatives is suggestive of typical opportunistic behavior with pathogenic potential, there is currently no evidence for the participation of either P. fragi and P. lini as aethiological agents of disease in fish.…”

The role of muscle-invading anisakid larvae on bacterial contamination of the flesh of post-harvest blue whiting (Micromesistius poutassou)

“…fluorescens is a commonly occurring fish spoiler, where some strains produce TMA and could be the TMA-contributor in the samples added Anisakishomogenate, together with P. phosphoreum (Gram and Dalgaard, 2002). P. fragi is mainly associated with a sweetish and fruity odour due to the production of ethyl esters, and could be responsible for the characteristic sweetish spoilage odour in the no[parasite] samples (Miller et al, 1973a). Since the PCR-DGGE method seems unable to differentiate between the two species, probably due to sensitivity constraints, it is not possible to decide if it was the same Pseudomonas species in all samples.…”