Dried fish is one of the traditionally preserved foods in Sri Lanka.Since dried fish is often an important component of daily meal, this study was aimed to assess the quality of selected dried fish varieties in the local market. Dried fish samples of nine selected varieties were collected under three categories, viz. locally produced, imported dried fish before and after distribution to retail market. They were analyzed for microbiological and chemical parameters. Water activity of the samples was also measured. Samples were found to be negative for Escherichia coli, Staphylococcus aureus and halophilic bacteria. Aerobic Plate Count and yeast and mould count of the majority of the samples were within the acceptable limit. Histamine content exceeded 100 mg/kg level in 33% and 13% of imported and local samples respectively. Water activity of the samples was <0.75 except for imported prawn samples of retail outlets. There was no significant difference (p>0.05) between the analyzed parameters of all three categories.

No abstract

This study aimed to identify histamine-forming bacteria (HFB) and the sources of introduction of such bacteria to recommend control measures to mitigate histamine formation in yellowfin tuna (YFT). Field samples were collected from multi-day boats that landed at Dikkowita, Negombo, Trincomalee and Dondra fishery harbours. Ice from the fish holds (n=63) and chill transport vehicles (n=63), and swabs from the fish holds (n=63), the boat decks (n=63) and the skin of YFT (n=63) were collected. Fish loin samples (n=15), ice samples (n=36) and swabs from the skin of YFT (n=18), floor (n=18) and chill transport vehicles (n=18) were collected from fish processing plants. Presumptive HFB isolated from Nivens medium and Violet Red Bile Glucose (VRBG) agar were screened for histamine forming ability in Tripticase soy broth (TSB) supplemented with 1.0% L-histidine. HFB isolates were characterized by sequencing approximately 1400 bp of the 16S rDNA. Seven isolates that produced histamine in the range of 3000–4000 ppm in TSB isolated from ice samples, and a swab sample collected from the boat deck, were confirmed as Klebsiella aerogens (n=6) and Morganella morganii (n=1) respectively. Hafnia alvei (n=1), Serratia sp. (n=2), Citrobacter freundii (n=1), Rahnella sp. (n=1) and Aeromonas salmonicida (n=8) were also among the isolated histamine forming bacteria. Pseudomonas sp. (n=24) and Shewanella baltica (n=7), which are known as spoilage bacteria were also isolated and showed weak histamine formation. Hence, it is evident that histamineforming bacteria could be introduced into the fish from ice and contacting surfaces. This necessitates the practice of rigorous cleaning procedures and adaptation of proper postharvest handling procedures to minimize contamination of the fish.