Off-flavour in Nile tilapia (Oreochromis niloticus) cultured in an integrated pond-cage culture system

• Published in: Maejo international journal of science and technology Vol. 7; p. 1
• Main Authors: Gutierrez, Redel, Whangchai, Niwooti, Sompong, Udomluk, Prarom, Wiwat, Iwami, Norio, Itayama, Tomoaki, Nomura, Nakao, Sugiura, Norio
• Format: Journal Article
• Language: English
• Published: Chiang Mai Maejo University 01.01.2013
• Subjects: Anabaena; Brackish; Cyanobacteria; Microcystis aeruginosa; Oreochromis niloticus; Oscillatoria
• ISSN: 1905-7873; 1905-7873

Thai farmers are shifting to cage farming in ponds due to drastic fluctuations in production in river cages resulting mainly from deteriorating water quality and diseases. Cage culture of tilapia in ponds has its merits but it is not immune to off-flavour problems. This study compares the levels of off-flavour compounds: geosmin and 2-methylisoborneol (MIB), in Nile tilapia (Oreochromis niloticus) cultured alone in ponds (T1), alone in pond cages (T2), in ponds with caged catfish (T3), and in pond cages with catfish in ponds (T4). Off-flavour levels of caged tilapia in the Ping River were similarly determined for comparison. Analysis of geosmin and MIB by HS-SPME-GC/MS revealed that fish in all pond treatments were found to be off-flavoured. At harvest, Nile tilapia in pond cages had significantly higher geosmin and MIB levels (P<0.05) compared to tilapia from the Ping River cages. No significant differences were observed in both geosmin and MIB levels among the treatments for Nile tilapia and hybrid catfish. The levels of MIB were generally higher than those of geosmin in fish, pond water and sediment. The prevalence of MIB could be partly due to the presence of MIB-producing actinomycetes in the ponds as revealed from their isolation in tilapia's stomach from T4 case. Microcystis aeruginosa and known off-flavour producers, Anabaena spp. and Oscillatoria spp., colonised the ponds, indicating that the latter two cyanobacteria might have caused off-flavour in Nile tilapia raised in integrated pond-cage culture system. [PUBLICATION ABSTRACT]