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Indian Journal of Medical Microbiology, Vol. 24, No. 1, January-March, 2006, pp. 75-76 Correspondence Microbiological safety of street vended fruit chats in Patiala city Kumar M, Agarwal D, Ghosh M, Ganguli *A Department of Biotechnology and Environmental Sciences, Thapar Institute of Engineering and Technology, Patiala - 147 004, Punjab, India Correspondence Address: Ganguli *A, Email: aganguli@mail.tiet.ac.in Code Number: mb06019 Dear Editor, Street-vended foods are appreciated for their unique flavours and convenience, as well as for maintaining the nutritional status of the population. They also assure food security for low-income urban population and livelihood for a significant proportion of the population in many developing countries. In spite of these potential benefits, street foods have been reported to be contaminated with pathogens and have also been implicated in food-borne epidemics.[1] Raw foods, especially ready-to-eat salad vegetables, sprouts and cut fruits have been implicated in outbreaks of food borne diseases in both developed and developing countries.[2] 'Fruit chats' comprising of slices of banana, guava, papaya and apple with a dash of salt and lemon juice enjoy a very high consumer preference in Northern, Western and Eastern parts of India. Fruit chats are usually consumed as a nutritious midday meal or as an accompaniment to meals and like all street foods are exposed to the abundant sources of contamination and could be important in causing food borne illnesses to consumers. In the present study, we selected the city of Patiala to assess the microbiological safety of fruit chats where the latter is appreciated and consumed by people across the socio economic spectrum. A total of 150 samples were collected from five major areas, which represented whole of the city and served at least 100 customers (all income groups) per day. All samples were collected from the vendors in presterilized zip-lock bags (HiMedia, Mumbai) and transported to the laboratory on ice and analysed within 1-2 hours of procurement. Portions of fruit chats weighing 25g were diluted with 250mL of sterile Butterfields phosphate buffer, blended for two minutes and diluted tenfold with the same. Appropriate dilutions were enumerated using standard bacteriological procedures. [3] for total aerobic plate counts using plate count agar, total faecal coliforms using violet red bile agar and Staphylococcus aureus using Baird-Parker agar. For detecting the presence of Salmonella , 10g portions of 'chutneys' were pre-enriched with 100 mL universal pre enrichment broth for 24 hours at 37 0C following which 0.1mL of the preenriched culture was inoculated in semisolid Rappaport Vassilidis agar and incubated at 42 0C for 24 hours, loopful portions of the latter were streaked on xylose -lysine desoxycholate agar; presumptive isolates of Salmonella were sent to the National Centre for Escherichia coli and Salmonella , Central Research Institute, Kasauli, India for further confirmation . Presence of Shigella was also assessed. Isolates of S.aureus obtained on Baird-Parker agar were characterized for their production of coagulase, thermostable DNAse activity, catalase, hemolysin production and mannitol fermentation.[3] The production of enterotoxins - A, B, C and D by all isolates of coagulase positive S.aureus strains were confirmed using a reversed passive latex agglutination based kit (SET RPLA, Oxoid).[3] The mean total aerobic plate counts (APC) and total staphylococcal counts (TSC) obtained were 8.46 log cfu/g (2.88x10 8cfu/g) and 6.98 log cfu/g (7.5x10 6cfu/g) whereas the mean total faecal coliform (TFCC) and total coliform counts (TCC) were 6.93log cfu/g (8.5x10 6cfu/g) and 6.67 log cfu/g (4.6x10 6cfu/g), respectively [Table - 1] Coagulase positive S.aureus was detected in 66 (44%) samples, of which 38 produced enterotoxins B and C. Salmonella enteritidis was found in 3(2%) of the samples . Shigella spp. was not detected in any sample. The high total aerobic plate counts indicated poor general quality of the fruit chats. Both total coliform and the total faecal coliform counts were notably high indicating faecal contamination of the samples. The high total Staphylococcus counts and the presence of enterotoxigenic S.aureus may be attributed to totally unhygienic handling by the vendors. Qualitative analysis showed the presence of Salmonella enteritidis in three samples, which further confirms the poor microbiological quality of these products. Hazard analysis and Critical Control Points- Total Quality Management lay down the microbial quality of raw foods. [4] Food containing < 4 log 10 cfu/mL of organisms is rated "good" and those containing approximately> 8 log 10 cfu/mL as spoiled food. In adittion, the suggested level of E.coli for the purchaser is < 10cfu/g. Our study indicated a prevalence of S.aureus which is able to grow at wide range of pH (4.8-9.3) and temperatures (7-43 o C). Although enterotoxin production is mediated only by cells of high population (10 8 cfu/g), a high number of S. aureus may result in the production of enterotoxins [2] causing food-borne diseases. Furthermore, growth of these pathogens, especially in the fruit chats (pH of fruit surfaces range from 6.5-7.5) during the long display periods (6-8 hours) at ambient temperature is quite possible. Salmonella enteritidis may have been transmitted through the hands of the vendors or from those of vendors who sold egg products in the vicinity. Although raw eggs and egg products have been implicated in contamination with Salmonella enteritidis the ability of this pathogen to survive for up to 7-14 days on the surface of many fresh fruits as in melons have been reported.[2] Since, people of almost all ages and income groups have a high preference for these product- possibility of food related outbreaks of diseases cannot be ruled out. We recommend appropriate intervention by regulatory authorities to ensure safety of such food available in the market. References
Copyright 2006 - Indian Journal of Medical Microbiology The following images related to this document are available:Photo images[mb06019t1.jpg] |
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