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Assessment of Microbiological Quality of Some Drinks Sold in the Streets of Dhaka University Campus in Bangladesh

Mahbub Murshed Khan
Institute of Nutrition and Food Science, University of Dhaka, Dhaka, Bangladesh

Md Tazul Islam
Department of Food Technology and Nutrition Science, Noakhali Science and Technology University, Noakhali, Bangladesh

Mohammed Mehadi Hassan Chowdhury
Department of Microbiology, Noakhali Science and Technology University, Noakhali, Bangladesh

Sharmin Rumi Alim
Institute of Nutrition and Food Science, University of Dhaka, Dhaka, Bangladesh

Abstract/ Executive Summary:

Background

Various kinds of fruit juices and sherbets sold by the street vendors are widely consumed in Dhaka city. These street vended fruit juices and sherbets are usually high in microbial loads. So, the present study was undertaken to assess the microbiological load, possible risk factors and identity of freshly squeezed juices and sherbets and their safety for human consumption in terms of pathogens.

Result

For the study purpose papaya juice, sugarcane juice, tukmaria sherbet, lemon sherbet and wood apple sherbet were taken as samples. The study showed a high microbial load in the drinks. The range of average total viable count (microbial load) and total coliforms were 7.7 × 10³ - 9 × 10⁸ cfu/ml and 210–1100 cfu/100 ml, indicated the heavy presence of microorganisms in all the drinks analyzed in this study. The study revealed that tukmaria sherbet was most contaminated with a count of 9 × 10⁸ cfu/ml. The least contamination was observed in lemon sherbet. A count of 1.98 × 10⁶ cfu/ml was observed in papaya juice and 3.4 × 10⁵ cfu/ml was in wood apple sherbet. Total coliforms were present in all samples and average count for total coliforms was high in tukmaria sherbets than others. Various pathogenic species of bacteria such as Proteus sp., Enterobacter sp, E. coli, Shigella sp, Citrobacter sp, Vibrio sp, Yersinia sp and Hafnia sp were isolated from the juices and sherbets. Unhygienic water for dilution, dressing with ice, prolonged use without refrigeration, insanitary surroundings, raw materials, chemical properties, equipment, fruit flies and airborne dust are the risk factors of contamination.

Conclusion

It was revealed that consumption of these street drinks were harmful for people. These drinks can cause various food borne illnesses. People should avoid these drinks.

Keywords: Microbiological quality, Drinks sold, Streets of Dhaka University Campus, Bangladesh

Location: Institute of Nutrition and Food Science, University of Dhaka, Dhaka, Bangladesh

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Juice

Objectives:

The present study was undertaken to assess the bacteriological load and identity of freshly squeezed juices and sherbets and their safety for human consumption in terms of bacterial pathogens.

Methodology:

Sample collection

Two different types of drinks were taken as sample for the study purpose; these were 1) Fruit juice and 2) Sherbet. There were two varieties of fruit juices namely papaya juice and sugarcane juice, and three types of sherbets namely tukmaria sherbet, lemon sherbet and wood apple sherbet. 3 samples of each type, total 15 samples were collected for test. The drinks were collected in sterile containers from the different vendors of five different places of Dhaka University Campus. The vendors were the drink and juice producers and they produced these in their makeshift stalls with unhygienic raw materials such as water, ice, syrups etc. and environment. The containers were kept in ice-boxes and transported to the laboratory.

Sample processing

The samples were in liquid form, so further processing was not required. One ml of liquid sample was taken and transferred into sterilized cotton plugged test tubes containing 9 ml of 0.1% peptone water. Then they were mixed thoroughly by shaking 20 times. This time the solution was allowed to stand for 5-10minutes.Thus initial dilution of homogenate was prepared and from this homogenization further serial dilution were prepared.

Bacteriological studies

Pour plate method was used for the determination of total viable count using total plate count agar for water. This media is unique and nonselective to count bacteria and fungi. The samples were diluted at 10 fold dilution up to 10⁻⁶ according American public Health Association (APHA) sample dilution guidelines (APHA 1992). Two plates from every dilution for each temperature at (36 ± 2)°C for (44 ± 4) hrs for bacteria and (22 ± 2)°C for (68 ± 4) hrs for yeast & molds were incubated. To identify the isolated bacteria; cultural, morphological and biochemical characteristics were studied carefully by using “Bergey’s Manual of Determinative Bacteriology”, 9th Ed. (Holt et al. 1994). Different types of selective agar were used for isolation and identification of bacterial colonies using streak plate method. The instructions for using of media were followed by guidelines of producing company. MacConkey agar was used to isolate Gram-negative enteric bacteria. To isolate and differentiate between Shigella sp. and Salmonella sp. SS agar was used because it was a differential media. TCBS agar was used as a selective media to isolate Vibrio spp. EMB (Eosin methylene blue) agar was used for the isolation of E.coli as a selective medium for E.coli and Proteus. The bacterial colonies grown on different types of medium were collected and maintained in Nutrient slant agar for further analysis. Some biochemical tests such as Kliger’s Iron Agar (KIA) test, Motility test, Imvic test, Indole test, Urea (MIU), test Catalase and Oxidase tests were performed for the identification of bacterial isolates. MPN method is used for the quantitative estimation for coliforms using three test tubes where inoculums size were 10, 1, 0.1 ml. MacConkey broth and BGLB (Brilliant green lactose broth) were used in this experiment (APHA 1992).

Source of Information: International Journal of Food Contamination 2, Article number: 4 (2015)

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Low price and availability make the street vended juices and sherbets highly popular to general people. But these drinks will be beneficial if these are free from contamination. The current study revealed that all the studied fruit juices and sherbets had a higher microbial load than the specification set for fruit juices in some parts around the world. Regular monitoring of the quality of fruit juices for human consumption is recommended to avoid any future bacterial pathogen outbreak.

Knowledge Management: Journal