AEI 5:107-116 (2014)  -  DOI: https://doi.org/10.3354/aei00100

ABSTRACT: Pangas Pangasianodon hypophthalmus and tilapia Oreochromis niloticus were cultivated for 6 mo in earthen ponds in Bangladesh to examine occurrence of the off-flavour geosmin in water and fish and to test procedures for reduction of off-flavour. In the ponds (~1 m depth and area of 400 m²), the average geosmin concentration was 3.9 ng l^-1 (range 0.2 to 20 ng l^-1). No effects of season or water treatment (sand filtration or probiotic microbes) were found. The content of geosmin in the fish was 21 ng kg^-1 (range: 0.0 to 91 ng kg^-1) for pangas and 17 ng kg^-1 (range: 0.0 to 68 ng kg^-1) for tilapia. Water treatment reduced the geosmin content by 56 to 74% in pangas, but no effect was found in tilapia. Likewise, depuration for ≥12 h in groundwater lowered the geosmin content in pangas (by 65 to 90%) but not in tilapia. Sensory analysis indicated a positive effect of both water treatment and depuration, and the fish were graded ‘no or mild flavour’ after such treatment, compared to ‘strong off-flavour’ in controls. Abundance analyses of known off-flavour producing microorganisms (streptomycete bacteria and cyanobacteria) showed a high density of streptomycetes (0.5 to 13% of the bacterial population), while cyanobacteria made up a maximum of 9.3% of the phytoplankton biomass or were absent. This first study on off-flavours in pangas and tilapia in Bangladeshi ponds indicates that geosmin was not a major off-flavour in the fish, but improvement of sensory quality by water treatment and depuration suggests that other, unidentified off-flavours were present in the fish.

KEY WORDS: Off-flavour · Aquaculture · Pangasianodon hypophthalmus · Oreochromis niloticus · Streptomycetes · Cyanobacteria · Geosmin · GC-MS · Sensory analysis

Full text in pdf format

Cite this article as: Petersen MA, Alam MA, Rahman MM, Ali ML, Mahmud S, Schlüter L, Jørgensen NOG (2014) Geosmin off-flavour in pond-raised fish in southern Bangladesh and occurrence of potential off-flavour producing organisms. Aquacult Environ Interact 5:107-116. https://doi.org/10.3354/aei00100 Export citation Share:    Facebook - - linkedIn