DETECTION OF FORMALIN AND QUALITY CHARACTERISTICS OF SELECTED FISH FROM WET MARKETS AT SYLHET CITY IN BANGLADESH

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1 BANGLADESH RESEARCH PUBLICATIONS JOURNAL ISSN: , Volume: 7, Issue:, Page: 6-69, July - August, 0 DETECTION OF FORMALIN AND QUALITY CHARACTERISTICS OF SELECTED FISH FROM WET MARKETS AT SYLHET CITY IN BANGLADESH M. M. Rahman*, S. Ahmed, M. M. Hosen and A. K. Talukder M. M. Rahman, S. Ahmed, M. M. Hosen and A. K. Talukder (0). Detection of formalin and quality characteristics of selected fish from wet markets at Sylhet city in Bangladesh. Bangladesh Res. Pub. J. 7(): Retrieve from Abstract Formaldehyde is unethically used by some fishermen and fish vendors to preserve the fish and seafood from microbial spoilage. The study was undertaken to determine the presence or absence of formaldehyde and some quality characteristics of fish from wet markets. Information was collected from fish retailers and consumers about the use of formalin in fish through the survey. The retailers easily recognize the fish coming from far distance on the basis of organoleptic characteristics such as color,, texture and general appearance etc. The retailers also claimed that they did not use any type of chemicals for increasing shelf life. Studies were conducted on the detection of formalin on fish obtained from different markets by formalin detection kit. We found 6 formalin treated fish out of 0 samples in which 6% in Modina Market, 6% in Ambar Khana, % in Lal Bazar, % in Kazir Bazar and 6% intucker Bazar. Studies were also conducted on the quantitative changes of bacterial load in fish. The average aerobic plate count (APC) under controlled condition of Rohi (Labeo rohita), Mrigal (Cyprinus mrigala), Shrimp (Marobrachium rosenbergii), Hilsa (Hilsa ilisa) and Catla (Catla catla) were cfu/g, cfu/g, cfu/g, cfu/g and cfu/g respectively. The ph of all selected fish ranged from 6.7 to 7.. In this study, the average ph value recorded of Rohi, Mrigal, Shrimp, Hilsa and Catla were 6.7, 6.8, 6.87, 6.79 and 6.87 respectively. There was no significant difference among fish purchased from different wet market. Keywords: Fish, Formalin, Microbial quality, Organoleptic, Wet market Introduction Fish and seafood are an important part of a healthy diet and are considered as the biggest source of protein (Ashie et al., 996). Fish culture has been contributing significantly to the export earning, employment generation, poverty alleviation and to the economic development of Bangladesh. Bangladesh has a vast fisheries resources comprising of fresh, brackish and marine waters inhabited by 96 fresh and brackish water species and marine species, 4 exotic species of fish and 4 species of prawn (DoF, 009). Available endemic species includes species of carps (both major and minor) and 4 species of catfishes including Indian major carp: Catla (Catla catla); Rohi (Labeo rohita); Mrigal (Cirrhinus mrigala) and the River shad (Tenualosa ilisha). Although the total fish production has increased significantly over the last few decades (DoF, 009), it is still not sufficient to meet up the growing demand of the country. This paves the way of entering imported fishes from neighboring countries into the domestic * Corresponding author: bau_mintu@yahoo.com, Department of Food Engineering & Tea Technology, SUST, Sylhet-4 Department of Microbiology & Hygiene, SAU, Sylhet-00

2 Rahman et al. market. It was reported that more than 80 MT of fish and fishery products enter into Bangladesh every day through the Teknaf border from Myanmar (Kibria, 007). By composition, fish contain fat free amino acids and water which is susceptible to spoilage by microorganisms and biochemical reactions during post mortem process (Fernandes and Venkatraman,99; Ismail, 00). Thus, fish and seafood are very perishable and can only be kept fresh in ice for 8 to 4 days depending on the species. In order to keep the freshness of fish and seafood, fishermen and fish vendors tend to intentionally and carelessly use formaldehyde as preservative agent. Available reports suggest that formalin is sometimes added or sprayed to the fishes by the fish traders while transporting to domestic marketing chain to prevent spoilage and increase shelf life (BFRI, 006). The traders may dip the whole fish or inject formalin in the fish body cavity or spray formalin mixed water on the surface while the fish are displayed in the retail market. It is not known whether some local fish are also sprayed with formalin to prevent their spoilage (Kibria, 007). Formalin is a generic term which describes a solution of 7% formaldehyde gas dissolved in water. Solution of formalin for use in fish should contain 0-% methanol which inhibits formation of a highly toxic compound. Recently, International Agency for Research on Cancer (IARC) has classified formaldehyde as a Group carcinogenic to humans (004). According to the United States Environmental Protection Agency (EPA), maximum daily dose reference (RfD) for formaldehyde is 0. µg/g body weight per day (Wang et al., 007). In 98, Italian Ministry of Health has proposed formaldehyde values of 60 µg/g and 0 µg/g for Gadidae (family of marine fish) and crustaceans(arthropods), respectively (Bianchi et al., 007). Now-a-days available reports in the newspaper, the dishonest businessmen are using formalin in fish to keep freshness or shelf life for longer time without signs of spoilage (Sapthahik, 0). They have very little knowledge about formalin s effect on human body. They know very well that formalin is not allowed to use in fish in our or in foreign countries. Although, formalin is still one of the most effective and widely used compounds in fish culture for therapeutic and prophylactic treatment of fungal infection and external parasites of fish egg. Considerable information is available on the shelf life of fish under various storage conditions by determining organoleptic and physical characteristics. Passy et al., (98) studied the combined effect of Initial microbial count, storage temperature and CO flushing of the package on shelf-life of fresh fish. The organoleptic quality of locally produced fishes such as Rohi, Catla and Hilsa was found with natural flavor and. The gills were red and the eyes were full bloom and bright appearance. The eyes were bulging with protruding lens and transparent. There were no slime on the surface of the body, and flesh was firm and elastic. All the locally produced fishes available in the market were organoleptically excellent condition. On the other hand, organoleptic characteristic of imported fishes such as of neck, of gill, colour of gill, general appearance, eye, slime and consistency of flesh of imported fish were not satisfactory and unacceptable. Besides p H is the most critical factor affecting microbial growth and spoilage of foods. The ph of living fish, although generally between 6.7 and 7.0, is subjected to variation with time of year, feeding, and degree of activity of the fish (Woyewoda et al., 986). Almost all freshwater fish inhabit waters with a ph from.0-9.0, with the majority of these inhabiting water with a slightly acidic to neutral ph (6-7.) (Kyrana et al., 997). Liken ph to the way the water "feels" against their skin. Low ph is highly acidic, burning their skin; high ph is highly alkaline, chapping their skin. When ph varies more than in a 4-hour, 6

3 Formalin Detection from fish wet markets the water experiences what is called a ph swing. Swings are very dangerous, as they interfere with basic body functions, leaving fish vulnerable. In Bangladesh, the fish marketing system is a traditional, complex and less competitive but relatively efficient one. However, it faces serious problems, including heavy losses and waste and poor quality. Since fish demand generally exceeds supply, there is limited incentive for traders to improve the quality of marketing system. During transportation of large quantities of fish to more distance, agents or wholesaler are not using adequate quantity of ice for short term preservation which leads to shortened shelf life of fish. Quality loss also occurs due to rough handling when the fishes are transported to market with ice by means of trucks, carrier launches and rail way for short and long distance transport (Reza et al., 009). As a result, considerable portion of total fish lose its quality by the time it reaches to the consumer. There is lack of studies on the marketing of commercially important fishes in the markets of Sylhet city. Besides, there is no information available whether formalin treated fish are marketed in this region or not. The study attempts to have and understanding on the present status of formalin treated fish and quality characteristics available in different markets of Sylhet city in Bangladesh. Materials ad Methods Selection of fish sample and area There is a large number of fish market in Sylhet City. We visited several fish markets and selected five important fish markets in Sylhet city i.e. Modina Market, Ambar Khana, Lal Bazar, Kazir Bazar, Tucker Bazar for our experiment because of their location, large scale marketing, economic condition of the inhabitants etc. 0 samples under five species fish such as Rohi (Labeo rohita), Mrigal (Cyprinus mriga), Shrimp (Marobrachium rosenbergii ), Hilsa ( Hilsa ilisa) and Catla (Catla catla) were collected from these market for the determination of formalin and quality characteristics. Determination of Defect points by Organoleptic method Sensory methods are used to assess the degree of freshness based on organoleptic characteristics such as general body appearance, consistency of flesh,, colour, eye and gill condition etc. Ranking systems have been developed to evaluate the judgments or results (Table ). Sensory methods have advantages that it can be adapted by the human being easily and the quality can be assessed by or visual inspection for quality defects. Human senses indeed are more efficient in some complex tasks than the instruments. There is, however, no single satisfactory test developed for the quality assessment of fish. A combination of chemical, biological and organoleptic tests would be the best procedure to assess such freshness. 6

4 Rahman et al. 64 Table. Determination of Defect points by Organoleptic method Characteristics of whole fish of neck when broken of gills Colour of gills General appearance Slime Eye Texture Defect characteristics Natural or Neutral Faint of medium of strong sour putrid Natural/Neutral Faint sour Slight to moderate sour Moderate to strong sour Slightly pinkish red. Pinkish red brownish red, some mucus may be present Brownish or gray colour and may be cover with mucus. Bleached; thick yellow slime Full bloom; bright, shining, and iridescent. Slight dullness and loss of bloom Definite dullness and loss of bloom Reddish lateral line; dull, no bloom Usually clear, transparent and uniformly spread Becoming turbid opaque and milky Thick, sticky, yellowish or green in colour Bulging with protruding lens; transparent eye cap Slight cloudy of lens and sunken Dull, sunken, cloudy Sunken eye covered with yellow slime Firm and elastic; Moderately soft and some loss of elasticity; Some softening Limp and floppy Direct points Grade * * * * Less than - /, to less than - Good/, and above- Bad/ Determination of Formalin on Selected Fish At first, the samples were washed with small quantity of water. Three drops washed-out water was taken in a test-tube using a dropper. Formalin detection kit in food developed by Bangladesh Council of Scientific and Industrial Research (BCSIR) was used in this experiment. The kit contains three solutions (No. -). Added drops from solution No. in the test-tube containing washed-out water. After well stirring, the solution was allowed to wait for 0 seconds. Then drops from solution No. were added in the same test-tube containing solution. After well stirring, the solution was also allowed to wait for 0 seconds. After then drops from solution No. were added in the same test-tube containing solution.

5 Formalin Detection from fish wet markets After adding No. solution, if the color of the solution changes into pink or red color, the presence of formalin will be ensured. On the other hand, if the colour of the solution remains unchanged, there is no formalin in the sample. Determination of ph on Selected Fish Ten (0g) gram of sample was removed aseptically from the body of the fish with sterile sharp knife. Then it is finely ground by using blender and homogenized thoroughly with 00 ml distilled water for minutes. Then, the ph of fish was recorded by the Digital ph meter. Determination of Microbial quality on selected Fish Standard plate count expressed as colony forming units per gram (cfu/g) of muscle of the fish samples were determined by consecutive decimal dilution techniques using spread plates. i. Dilution Ten gram of sample was removed aseptically from the body with sterile knife and then homogenized with 90ml of sterile saline solution (0.8 NaCl) in a sterile blender jar to obtain :0 dilution..0 ml of diluted sample was transferred with a sterile pipette to test tube containing 9.0 ml of 0.8% physiological saline and the test tube was shaken thoroughly for mixing. Using similar process several dilutions were made up to the desired level. ii. Total plate count All plating was done on nutrient agar..0 ml of desired dilution of sample was pipetted out and transferred aseptically to the agar plates by raising the upper lids sufficient enough to admit the tip of the pipette. The sample pipette into the plate were spread by L-shaped glass rod throughout the surface of the media until the sample were dried out. The plates were incubated at 0 0 C in inverted position. After 48 hrs of incubation, the plates having 0 to 00 colonies developed were counted in order to get the cfu/g. 6 Where, C = Number of colonies found D = Dilution factor V = Volume of original sample S = Weight of sample in grams cfu = Colony forming unit. Results and Discussion Detection of Organoleptic quality of selected fish Table shows the organoleptic quality changes in Rohi, Mrigal, Shrimp, Hilsa and Catla. The quality was evaluated by grading the fish using the score from less than to and above based on organoleptic characteristics such as color, and general appearance. The grade defined in terms of the total number of points was less than considered as very excellent or acceptable; to less than good or acceptable; and above very bad or rejected condition. In controlled samples, the organoleptic characteristics such as appearance, textural condition, color and indicated that the Rohi fish bear all of good characteristic such as natural, bright shining, firm & elastic consistency. Mrigal & Shrimp do not maintain the standard organoleptic characteristics. So they are not acceptable in condition. The sample Hilsa and Catla shows some good and bad characteristics. So they are acceptable in condition.

6 Name of the fish Rohi Mrigal Shrimp Hilsa Catla Rahman et al. Table. Determination of defect points of fish Natural Some loss of natural Slight Loss of Natural Natural Natural of gill Natur al Slight mode rate to strong sour Slight mode rate to sour Slight mode rate to strong sour Mode rate to sour Color of gill Sligh t pun kish red Brow n or grey colo r Sligh t pinki sh red Sligh tly pinki sh Pinki sh Colo ur Detection of formalin in fish Defect characteristics General appearace Full bloom, bright shinning Definite dullness and loss of bloom Full bloom; bright; shining Bright shining Full bloom Eye Slime Consist ency of fish Bulgi ng with protr udin g lens Dull, sunk en, Clou dy Bulgi ng with Protr udin g lens Sunk en clou dy Sunk e eye cove red with yello w slime Usuall y clear, trans paren t Beco ming turbid opaq ue and milky Usuall y not clear Usuall y clear Thick, sticky, yello wish or green in colou r Farm & elastic Defect points Some softeni ng 66 Overall grade Not softeni ng Not acceptable Moder ately rigid acceptable Moder ately rigid acceptable Studies were also conducted on the detection of formalin in fish obtained from different markets and the results are presented in Table. It was found that Rohi, Catla and Hilsa produced locally were formalin free. On the other hand, formalin was detected in imported Rohi and Catla which were selling in different markets of Sylhet city. Studies were also conducted upon 0 (0 samples from each market) samples that 6% formalin treated fish found in Modina Market, 6% in Ambar Khana, % in Lal Bazar, % in Kazir Bazar and 6% in Tucker Bazar. It was observed that in formalin treated fish, there was a chance of washing out of formalin from the surface of the fish body along with melting of ice. This is why the retailers do not use any type of ice while selling to consumers. Besides of all

7 Formalin Detection from fish wet markets retailers have little or no information about the use of any types of chemicals which creates health hazard in human for increasing the shelf life of the fish in the wholesale or any other marketing chain. Table. Formalin detection in fish Name of the markets Modina Market Ambar Khana Lal Bazar Kazir Bazar Tucker Bazar Name of the fish Amount of ph in selected Fish Polled sample (No. of fish) Formalin presence (p) or absence (A) in fish Rohi 6 P () Shrimp 6 P() Catla 6 A Rohi 6 P() Shrimp 6 P() Catla 6 P() Rohi 6 A Shrimp 6 P() Catla 6 P() Rohi 6 P(4) Shrimp 6 P() Catla 6 A Rohi 6 P() Shrimp 6 A Catla 6 P() Total formalin treated fish 67 Percentage (%) 6% 8 6% 4 % 7 % 6% P H first decreases with the onset of rigor but then progressively increases from microbial activity. For some fish, a ph value greater than 7.0 indicates spoilage (Woyewoda et al., 986). The ph in fish tissues drops due to smoking (as preservative), generally to 6. or less (Doe, 998). Table shows the results for ph of the selected fish from different wet markets. The highest ph recorded was in Shrimp and Catla at The lowest ph was found in the Rohi sample at 6.7. The lowest ph of the fish muscle was due to the glycogen in the muscle which would have been metabolized to lactic acid by then and would account for the low ph recorded. The typical ph of live fish muscle was equivalent to 7.0. The production of alkaline bacterial metabolites in spoiled fish which coincided with the increase in Total Volatile Basic Nitrogen (TVB-N) might increase the ph level of samples. The increase in ph in fish muscle occurred due to the storage period which was also associated with the state of rapid spoilage of fish. Thus the fish might have been stored for a long period before being distributed to wet markets.

8 Rahman et al. Table. ph of fish from different wet markets Name of the ph markets Rohi Mrigal Shrimp Hilsa Catla Modina Market Ambar Khana Lal Bazar Kazir Bazar Tucker Bazar Mean Minimum Maximum Microbiological profile Aerobic plate count in Bacto nutrient agar for producing bacteria for all fish types from five different wet markets were shown in Table 4. The highest total plate count was found in the Hilsa sample at cfu /g while the lowest count was in the Rohi at cfu /g. The higher value for total plate count that ranged from 0 to 0 7 cycles might due to improper handling of fish in wet markets and cross contamination might have occurred. Based on the data collected, these samples are still not considered as spoiled. During the aerobic storage, specific spoilage bacteria should be around 0 8 to 0 9 cfu/g to produce significant amount of chemical compounds associated with spoilage (Huss, 99.). These results are in agreement with putrescine and cadaverine forming bacteria in anchovies stored in ice (Pons-Sánchez-Cascado et al., 00). Table 4. Aerobic plate count (at 7 C) of selected fish from wet market Name of the Bacteriological count, CFU/g markets Rohi Mrigal Shrimp Hilsa Catla Modina (F) Market Ambar Lal Kh Bazar.4 0 (F) Kazir Bazar (F) Tucker Bazar Mean Minimum Maximum Note: F stands for formalin treated fish. Conclusion The present study gives information about the influence of formalin on quality changes of fish such as Rohi, Mrigal, Shrimp, Hilsa, Catla with the ranges 6% to 6% formalin treated fish found in different market of Sylhet city where the oprganoleptic qualities were poor compared to non-treated fish. Based on the findings of study, it can be seen that the imported fishes are not meet the consumer demand because of their unacceptable organoleptic characteristics. On the other hand, the consumer prefers the locally caught fish. Although it is necessary to conduct such type of study in whole different fish markets, this study reveals an idea of the extent of formalin contamination of fish in Bangladesh. So 68

9 Formalin Detection from fish wet markets the government and other agencies need to take necessary steps to prevent such type of blacken activates by the fish traders to safe guard public health. References Ashie, I. N. A., Smith, J. P., Simpson, B. K. and Haard, N. F. (996). Spoilage and shelf-life extension of fresh fish and shellfish. Critical Reviews in Food Science and Nutrition 6 (&): P: 87-. BFRI (Bangladesh Fisheries Research Institute) (006). Presence of formalin in fish and its affect on fish quality. In: Research progress report for P Bianchi, F., Careri, M., Musci, M. and Mangia, A. (007). Fish and food safety: Determination of formaldehyde in fish species by SPME extraction and GC-MS analysis. Food Chemistry 00: P Doe, P.E. (998). Fish Drying and Smoking Production and Quality. Technomic Publishing Co., Inc. Lancaster, Pennsylvania. DoF (Department of Fisheries) (009). Fish fortnight publication, 009. Published by the Department of Fisheries, Ministry of Fisheries and Livestock. Fernandes, G. and Venkatraman, J. T. (99). Role of omega- fatty acids in health and disease. Nutrition Research (): P Huss, H.H. (99). Quality and quality changes in fresh fish. FAO Fisheries Technical Paper 48, FAO, Rome, Italy. IARC (International Agency for Research on Cancer) (004). Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 88, International Agency for Research on Cancer, Lyon, France. Ismail, H. M. (00). The role of omega- fatty acids in cardiac protection: An overview. Frontiers in Bioscience 0: Kibria, G. (007). Formalin and Fish Trade in Bangladesh - Human and Environmental Risks. News article retrieved from the internet Kyrana, V.R., Lougovois, V.P. and Valsamis, D.S. (997). Assessment of shelf-life of maricultured gilthead sea bream (Sparus aurata) stored in ice. International Journal of Food Science and Technology (4): P Passy, R., Kapia T.A. and Stearling K. (98). Shelf life of fish and sea food. Critical Reviews in Food Science and Nutrition 6(&): P Pons-Sánchez-Cascado, S., Bover-Cid, S., Veciana- Nogués M. T. and Vidal- Carou, M. C. (00). Amino acid-decarboxylase activity of bacteria isolated from ice-preserved anchovies. European Food Research and Technology 0 (-4): P. -. Reza, M.S., Bapary, M.A.J., Ahasan, C.T., Islam, M.N. and M. Kamal, (009). Shelf life of several marine fish species of Bangladesh during ice storage. Int. J. Food Science and Technology, 44: P Sapthahik (0). Business men using formalin in fish published in the newspaper Sapthahik-000. March,0.Bangladesh. Wang, S., Cui, X. and G. Fang, (007). Rapid determination of formaldehyde and sulfur dioxide in food products and Chinese herbals. Food Chem., 0: DOI: 0.06/j.foodchem Woyewoda, A.D., Shaw, S.J., Ke, P.J. and Burns, B.G. (986). Quality indices-lipid related. In Recommended Laboratory Methods for Assessment of Fish Quality. Canadian technical report of fisheries and aquatic science, Canada. 69