Bacterial contamination of fish sold in fish markets in the central province of Sri Lanka

This study was conducted to investigate the and the recent trend is for high quality products. bacterial, chemical and sensory quality of fish and sanitary ~ h ~ ~ ~ f ~ ~ ~ , t he present investigation was conditions of the sales outlets. The Salmonella sp.and Vibrio undertaken to evaluate the quality of the fish and cholera were not detected in fish samples investigated during the study. Of the fish samples analyzed 56.6% were found the handling practices adopted at several selected unsuitable for consumption. The sanitary conditions of 50% sales outlets in three different climatic zones. of the fish stalls were not within the stipulated standards. The estimated levels of total coliform and Escherichia coli in n%l3THODOLOGY the fish samples analysed were 7-2.4x103/g and <3-2.4x10Vg and the estimated maximum and the minimum counts of total bacteria were 3.25xlOVg and 6.83x1Og/g respectively. The presence of fecal Coliforms and E.coli in the tuna samples investigated can be attributed to the fecal contamination of fish from capture upto marketing.


INTRODUCTION
The present study was conducted at eight selected towns in three different climatic zones based on the ambient temperature. A=<P7 O C (Hatton and Nuwaraeliya), B=17-25 O C (Gampola and Nawalapitiya) and C = 25-26 O C (Dambulla, Galewela, Matale and K a n d~) .~ A total of 60 samples of tuna collected during the study were sensory analyzed, observed a n d scored organoleptically. Approximately 250 g of fish was purchased from each fish stall. Eight fish stalls The marine fisheries sectors is one of t h e were visually evaluated for the sanitory facilities important sectors of the Sri Lankan economy, available and scored using a scoring system contributing to approximately 2.8% of the gross developed previously. The number of fish stalls domestic production (GDP) of the island.' The analyzed from each town varied from -6. importance of fish as a source of animal protein i s well understood a n d t h e avoidance of unnecessary quality losses and the contamination ofharvested fish with pathogenic bacteria are very important. The number and the nature of the bacteria on fish are affected by many factors such as sea water pollution, temperature, method of capture, preservation methods adopted and handling practices. The fish that live in water polluted with human and the animal fecal matter may carry substantial numbers of bacteria such as Salmonella, V. cholera, Clostridium botulinum, E. coli a n d other Coliforms. The quality requirements of consumers have been changing The samples collected from each fish stall were labeled, sealed in polythene bags and stored in an insulated box containing ice packs. Four visits were made to each sales outlet and a triplicate of t h e samples were analyzed. Laboratory analysis was carried out according to previously established methods3 to determine the levels of Salmonella, V. cholera , Total Bacterial Count (TBC), Total Coliform (TC) , Fecal Coliform (FC) and the E. coli. The Total Volatile Nitrogen (TVN) content of these samples were also determined.4

RESULTS AND DISCUSSION
The microbiologgcal analysis revealed that, none of the samples investigated contained Salmonella and V. cholera indicating that the fish marketed in the Central Province were free from highly pathogenic bacteria. However, of the total samples investigated 56.6% were not suitable for consumption. This figure was much higher in the samples collected from the sites with ambient temperature of 17 -25 C and 25 -26 C and were 65.4 and 77.8% respectively. In the <17 O C climatic zone, 81.2% of the samples were suitable for consumption.
On the average, 56.6% of the fish samples examined during the present study had thg TBC > 106/g. The estimated percentages of the fish samples containing TBC >106/g were very much higher in the temperature zones 17 -25 O C and 25 -26 O C and were 76.92% and 55.6% respectively. In the <17 O C temperature zone only 25% of the fish samples analyzed contained TBC >106/g. The study indicated t h a t there is a considerable influence of the ambient temperature on the TBC recorded in fish.
About 73.4% of the fish samples investigated during the present study contained the TC counts >102/g with a potential of causing health hazards.40% of t h e fish samples investigated had fecal coliform counts >102/g while 35% contained counts <50/g. Most of the samples contained E. coli counts >10/g while 16.67% of the fish samples were with counts >lo3/ g. The considerably high counts of coliform and E. coli recorded in this study indicates high fecal contamination of fish.
Majority of the samples analyzed (87.5%) contained TVN levels <30mg/100g. But in the 17O C-25O C and 25O -26O C temperature zones, 80.77% and 77.7% of the samples contained TVN levels >30mg/100g and only 19.23% and 22.3% of the samples were found to contain TVN <30mg/ 100g respectively. Since the above figures were more or less similar to the estimated TVN levels of the majority of fish samples analyzed during the present investigation, it is reasonable to conclude that these were in initial or advanced stages of spoilage.
The combined effect of poor sanitary conditions and high temperature exerted on fish over a long period, increases the rate of spoilage and reduces the nutritional quality of fish at sales outlets. Most of the fish vendors do not have the knowledge on factors affecting fish spoilage and how to regulate the process. Therefore, awareness programmes should be arranged to educate the fish venders on proper handling of fish. This would enable them to acquire quality fish safe for consumption. The study also indicated the importance of taking measures to improve the facilities of fish sales outlets, formulation of a mechanism for proper handling of fish from capture to marketing and also waste management.