M. Hossain
Department of Microbiology, Jashore University of Science and Technology, Jashore 7408, Bangladesh
B.K. Dey
Department of Fisheries and Marine Bioscience, Jashore University of Science and Technology, Jashore 7408, Bangladesh
Enterobacteriaceae, Bacterial Load, Colony Count, Microbial, Fast Foods, Bangladesh
Two sub-districts namely Jashore Sadar and Chaugachha of Jashore District, Bangladesh
Pest Management
Sample collection Two sub-districts namely Jashore Sadar and Chaugachha of Jashore District, Bangladesh were included in this study. A total of 30 samples comprising 15 Plum Sauce (PS) and 15 Tomato Sauce (TS) were collected from 30 different selected places (one sample from each site) in those selected sub-districts during March 2015. Also, all the 30 vendors were interviewed to know whether they received any food hygiene training. Samples were obtained from vendors, put into sterile containers, and then kept in an icebox. Immediately after collection, the samples were transported to the Laboratory of Microbiology, Jashore University of Science and Technology, Jashore, Bangladesh.
Enumeration of total bacteria and Enterobacteriaceae Overall bacterial cell enumeration was done by following dilution plate technique that had been described by Buchanan and Gibbons (1974). At first, 1 g of each sample was homogenized with 9 ml of sterilized distilled water. Thereafter, 1 ml homogenized sample was serially diluted for 10 times (10-1 -10-10). From each dilution tube, 0.1 ml liquid was spread on to the Nutrient Agar (Oxoid, UK) plate. The inoculated plates were incubated at 37oC for 48 h and then, the bacterial colonies were enumerated. The plates giving a range between 30 and 300 colonies were considered to take into account. Enumeration of Enterobacteriaceae was performed by following the same techniques, but Violet Red Bile Glucose Agar (Oxoid, UK) was used instead of Nutrient Agar; and the round purple colonies surrounded by a purple halo were considered to be Enterobacteriaceae colonies (FDA, 2002). For total bacteria and Enterobacteriaceae, presence of more than 103 and 104 Colony Forming Unit (CFU)/g sauce sample, respectively has been considered as unsatisfactory markers as recommended by CFS (2014).
Detection of Salmonella spp. Detection of Salmonella spp. was performed in accordance with Buchanan and Gibbons (1974) where Bismuth Sulfite Agar (Oxoid, UK) was used. The dilution step was the same as previously described in the section of “Enumeration of total bacteria and Enterobacteriaceae”. For instance, however, the dilution was performed up to 5 times (10-1 -10-5 ) instead of 10 times. Salmonella colonies were detected depending on their morphological characteristics and confirmed through further tests including biochemical tests. For Salmonella spp., presence of 0 (zero) CFU/25 g sauce has been set as an unsatisfactory marker based on CFS (2014).
Enumeration of E. coli E. coli was enumerated by using membrane filtration technique (0.45-micron cellulose nitrate filter paper) as previously described by Vergine et al. (2017). The dilution procedure was the same as previously described in the section of “Enumeration of total bacteria and Enterobacteriaceae”. For instance, however, 6-fold dilution was performed instead of 10-fold. Briefly, 1 ml liquid from each dilution was mixed with 9 ml of sterilized distilled water, and followed by filtration. The filter paper was placed on MacConkey Agar (Oxoid, UK), and incubated at 44 oC for 24-48 h. E. coli colonies were detected depending on their morphological characteristics and confirmed through further tests including biochemical tests. For E. coli, the presence of more than 102 CFU/g sauce has been considered as an unsatisfactory marker according to CFS (2014).
Journal of Food Quality and Hazards Control 6 (2019) 115-120
Journal