An investigation on the quality and handling practices of skipjack tuna (Katsuwonus pelamis) along the main commercial distribution channels of Beruwala fishery harbour
G.J. GANEGAMA ARACHCH1, M.G.I.U. KARTYAWASAM, P.P.M. HEENATIGALA, D.S.ARIYARATNE, T. DAHANAYEKA AND J.M.P.K. JAYASINGHE
Beruwala fishery harbour is one of the main fish-landing sites in Kalutara district in the southwestern coast of Sri Lanka. Skipjack tuna (Katsuwanus pelamis) is one of the major constituents of the catch of multi-day boats (MDRs) operated from this harbour. The marine fish catch landed in this district in 2001 was around 32110 mt. Recent studies based on sensory evaluation have shown that the post harvest loss of skipjack tuna at Beruwala fishery harbour is around 27±115%. Main objective of this study was to investigate the quality deterioration of skipjack tuna at different handling stages along the main commercial distribution channel starting from MDBs operating from Beruwala fishery harbour to final retailing stage that ends up at Matugama and Horana and to suggest remedial measures to reduce the quality deterioration along the handling chain. Mean Aerobic Plate Count (APC) of skinned fish from MDBs and pier were log 5.20±1.10 cfu/g and log 5.35±1.20 cfu/g respectively. APC of fish from transport vehicle, fish stall and retailed stage along Matugama channel were log 6.16±0.94 cfu/g, log 7.08±0.96 cfu/g and log 6.96±0.46 cfu/g respectively. In Horana distribution channel mean APC were log 5.14±0.71 cfu/g, log 6.13±t0.49 cfu/g and log 6.40±0.15 cfu/g in fish from vehicle, stall and retailed stage respectively. E.cail were positive (>10 cfu) in 17%, 43%, 50%, 87% and 100% of flesh (skinned) samples of skipjack tuna in MDB, at pier, in transport vehicle, at stall and retailed stage respectively. E.coli were found in skin-on samples from all stages and the range detected was 102-103cfu/g. The average ambient temperature recorded on board of the MDB during fishing trip was 29.8°C with a variation of ± 3.7°C. Core temperature of fish stored in fish hold in MDB, at pier, inside transport vehicle and stall in market were 2.7±2.1°C, 6.3±4.1 °C, 13.0±2.5°C and 17.0±2.4°C respectively. Fish is stored in fish hold of the MDB for about 7 days and after unloading, fish reaches retail shop within around 5 h. Based on criteria for levels of APC, six out of nine lots of fish were acceptable, in MDB, at pier and in vehicle. At retail stalls only three out of nine fish lots were acceptable. Average trimethyl amine (TMA) and total volatile base (TVB) contents of fish in all stages were found in the ranges of 7.67-11.89 mg/100g and 13.65-26.92 mg/100g respectively. Poor infrastructure and bad handling practices in boat, pier, transport vehicle, retail markets are found to be responsible for quality deterioration along distribution channel, which results in poor quality of fish available for consumers.