A Survey in Bacteriological Quality of Traditional Dried Seafood Products Distributed in Chon Buri, Thailand

P-ISSN 2586-9000 E-ISSN 2586-9027 Homepage : https://tci-thaijo.org/index.php/SciTechAsia Science & Technology Asia Vol. 24 No. 4 October - December 2019 Page: [102-114] Original research article A Survey in Bacteriological Quality of Traditional Dried Seafood Products Distributed in Chon Buri, Thailand Subuntith Nimrat1,2,*, Namphueng Butkhot2, Sireeporn Samutsan2, Kittikoon Chotmongcol2, Traimat Boonthai3 and Veerapong Vuthiphandchai4 1Department of Microbiology, Faculty of Science, Burapha University, Chon Buri 20131, Thailand 2Environmental Science Program, Faculty of Science, Burapha University, Chon Buri 20131, Thailand 3Biological Science Program, Faculty of Science, Burapha University, Chon Buri 20131, Thailand 4Department of Aquatic Science, Faculty of Science, Burapha University, Chon Buri 20131, Thailand Received 11 April 2019; Received in revised form 15 July 2019 Accepted 24 July 2019; Available online 31 October 2019 ABSTRACT This study aimed to assess physicochemical and bacteriological qualities of dried seafood products distributed in Chon Buri province, Thailand. Forty-four dried seafood samples were collected from local markets and examined for pH, water activity (aw), salt content, numbers of viable bacteria and halophilic and halotolerant bacteria, numbers of Escherichia coli and Staphylococcus aureus and the presence of Salmonella, Vibrio parahaemolyticus and Vibrio cholerae using a standard protocol. Values of pH, aw and salt content in dried seafood products were 5.16 ± 0.04 – 8.63 ± 0.03, 0.221 ± 0.01 – 0.822 ± 0.02 and 0.28 ± 0.03 – 18.92 ± 0.10%, respectively. Numbers of viable bacteria, and halophilic and halotolerant bacteria were 102 – 109 and 102 – 109 CFU g-1, respectively. Main compositions of total viable bacteria, and halophilic and halotolerant bacteria in dried seafood products were Staphylococcus, Bacillus and Pantoae. Based on regulatory standards for cooked ready-to-eat and prepared seafood products set by the Department of Fisheries, Thailand, nineteen (43.18%) samples contained viable bacteria numbers exceeding the allowable limit. Two dried shrimp products (4.55%) harbored E. coli over a regulatory acceptable value of 10 MPN g-1. All dried seafood products had S. aureus numbers within allowable limit for good quality of *Corresponding author: [email protected] doi: 10.14456/scitechasia.2019.31 S. Nimrat, et al. | Science & Technology Asia | Vol. 24 No. 4 October - December 2019 processed seafood products. None of Salmonella, V. parahaemolyticus and V. cholerae was isolated from all dried seafood products. This study indicates that consumption of cooked ready-to-eat and prepared dried seafood products may constitute a potential hazard of foodborne infection. Keywords: Dried seafood product; Viable bacteria, Halophilic and halotolerant bacteria; Water activity; Chon Buri 1. Introduction microorganisms. They are typically Seafood products have been widely preserved in plastic bags outside accepted as a good source of various therefrigerators and distributed in open essential nutrients such as proteins, markets; consequently, they are easily vitamins, minerals, omega-3 fatty acid and exposed to bacterial contaminants that may taurine [1]. Dried processed seafood contribute to morbidities and mortalities of product, a popular food in Thai cuisine due consumers. to its accustomed taste and aroma, is one of There have been a number of the most important processed food products pathogenic bacteria found in dried seafood to the economy of Thailand with export products such as Clostridium botulinum, revenue of $1,315 million in 2016 [2]. Staphylococcus aureus, Vibrio Major raw seafood materials, including parahaemolyticus, Listeria monocytogenes, shrimp, fish, crab, bivalve and cephalopod Salmonella Typhi and Salmonella caught from farms and the Gulf of Thailand, Enteritidis [3-4, 7]. The pathogenic bacteria have been supplying local facilities to could threaten consumer health, in particular produce a variety of dried seafood stuff. the food eaten without cooking before Traditional simple processes are applied to consumption. In addition, the high salt and seafood, e.g. drying, salting, brining, low moisture content characteristics of the marinating and fermenting, to retard traditional dried seafood products have spoilage and prolong the shelf-life [3]. contributed to propagation of pathogenic Traditional dried seafood products are halophilic and halotolerant bacteria [7, 8-9]. usually stable at high temperature, leading Diminished prevalence and growth to storage and distribution at ambient prevention of pathogens is necessary for the temperature for 6 months or more [4]. food safety and quality. During recent years, However, they are also vulnerable to human dried seafood products have been intoxication and pathogen contamination. confronted with stringent criteria enforced Despite high salt and low moisture contents by regulatory authorities. limiting growth of most microorganisms, Chon Buri is a popular province in the traditional dried seafood products have been eastern region of Thailand with 18.4 million also considered as a vehicle for a serious of visitors in 2018. By 2017, 88 local risk to human health in terms of factories associated with dried seafood contamination of indigenous and pathogenic production are found in Chon Buri province, bacteria derived from handling during which has a total processing capacity of ca. production processes [1, 5-6]. 4,841-t raw seafood materials to dried Unfortunately, traditional dried seafood seafood products per year [10]. In the past products in Thailand are produced under decade, several reports stated that traditional unhygienic processes and unawareness of dried seafood products distributed in Chon proper sanitation during distribution leading Buri province were not safe to a relatively high contamination of bacteriologically owing to contamination with high numbers of total viable count and 103 S. Nimrat, et al. | Science & Technology Asia | Vol. 24 No. 4 October - December 2019 pathogenic bacteria e.g. Salmonella, 2.3 Bacteriological analysis Staphylococcus aureus and Bacillus cereus Numbers of total viable bacteria, and [11-12]. To date, there is little scientific halophilic and halotolerant bacteria were information available enumerated using the spread plating method regarding bacteriological quality and safety [15-16]. A portion of a sample (50 g) of dried seafood products in Thailand. excised aseptically from each dried seafood Therefore, the present study aimed to product was homogenized vigorously with elucidate the physicochemical and 450 mL Butterfield’s Phosphate - Buffered bacteriological characteristics of traditional Dilution Water (BPD) using a stomacher for dried seafood products in Chon Buri 2 mins. Successive decimal dilutions were province, Thailand. prepared by mixing 1 mL of the previous dilution with the same sterile diluents (10 2. Materials and Methods mL). Then, an aliquot of each dilution (0.1 2.1 Sample collection mL) was plated in triplicate onto Plate Forty-four samples of a variety of Count Agar (PCA; BD Biosciences, Sparks, dried seafood products were purchased Maryland, USA) and PCA containing 7.5% monthly from five retail markets located in (w v-1) NaCl for counting numbers of total Chon Buri, Thailand between May 2011 and viable bacteria, and halophilic and April 2012. Dried seafood samples were halotolerant bacteria, respectively. All petri categorized into two groups: prepared dishes were incubated at 35 °C for 24 h. products that need minimum heating before Petri dishes with 25-250 colonies were consumption (dried shrimp, dried seasoned counted and calculated as CFU g-1. Bacterial whole fish, salted fish and dried mussels) isolates were purified by re-streaking on and cooked ready-to-eat products (seasoned Trypticase Soy Agar (TSA; BD fish strips, crispy rolled seasoned squids, Biosciences) or TSA added with 7.5% (w v- crushed squids in seasoned syrup and crispy 1) NaCl. The purified isolates were dried seasoned crabs). All samples were characterized on the basis of morphological wrapped in aseptic bags, placed in an icebox and biochemical characteristics [17-18]. and immediately transported to the Isolations of V. parahaemolyticus, V. laboratory within 2 h. cholerae, Salmonella, S. aureus, and total coliforms and E. coli were carried out 2.2 Physicochemical characterization according to the guidance of the US FDA The values of pH and water activity [15]. (aw) of dried seafood samples were Enumeration of V. parahaemolyticus examined according to the AOAC [13] was achieved by a three-tube MPN procedure. Dried seafood samples (10 g) enrichment method. A portion (25 g) of were homogenized with distilled water (10 samples was homogenized in 225-mL mL) in sterile sampling bags using a alkaline peptone water (APW), pH 8.5 0.2 stomacher (AES Laboratories, Combourg, using a stomacher and serially diluted by France). The homogenates were then 10-fold dilution technique. After incubation measured directly using a regular calibrated at 35 °C for 6-8 h, all turbid tubes were pH meter (Sartorius, Professional Meter PP- subcultured onto Thiosulfate Citrate Bile 50, Gottingen, Germany). Value of aw was salt Sucrose (TCBS) agar (BD Biosciences) determined using a water activity meter and incubated at 35 °C for 24 h. The green (Novasina MS 1, Lachen, Switzerland) at 25 and/or blue-green colonies were picked °C. Salt contents in dried seafood products from each sample and streaked on TSA were estimated using the

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