Street foods have been reported to be contaminated with pathogens and have
also been implicated in food-borne epidemics. It was found that in most localities,
the street foods remain hygienically poor since bacterial loads are moderately
high. Street foods like panipuri, bhelpuri and chaats are cheap, readily available
and appeal to the taste of common people in India, though they may be deficient
in nutritive value. Selection of street foods is based on taste, price and last
on nutritional quality (Bhat and Waghray, 2000).
Raw foods, especially ready-to-eat vegetable salads, sprouts and cut fruits
have been implicated in outbreaks of food borne diseases in both developed and
developing countries (Kumar et al., 2006). In
countries, where street food vending is prevalent, there is commonly a lack
of information on the incidence of food borne diseases related to the street
vended foods. However, microbial studies on such foods in American, Asian and
African countries have revealed increased bacterial pathogens in the food. There
have been documented outbreaks of illnesses in humans associated with the consumption
of street-vended foods (Mahale et al., 2008).
In India, chaats are sold at all public places and roadside shops. However,
their consumption, quick method of cleaning and handling, could often prove
to be a public health threat. There are reports of food borne illnesses associated
with the consumption of unhygienic foods at several places in India. Hazards
and critical control points (HACCP) conducted for a selected bhelpuri vendor
from urban Vadodara that involved microbial analysis of 8 ingredients of bhelpuri
and 7 samples indicative of personal hygiene and environmental sanitation showed
the presence of E. coli in almost all the samples and Salmonella
and Shigella in knife, hand rinse, dishwater and sevpuri samples (Sheth
et al., 2005). Bacteria like Salmonella sp. Shigella
sp. Campylobacter sp. and E. coli can contaminate the food
through contact with sewage and contaminated water (Fredlund
et al., 1987; Blostein, 1993; Beuchat,
1996; Gayler et al., 1955). Thus, the hazards
and critical control points identified were high initial contamination of raw
foods, poor personal hygiene and environmental sanitation, cross-contamination
between raw and cooked foods, holding of foods at ambient temperature and poor
cleaning practices for stall and utensils (Sheth et al.,
The consumption of these roadside foods potentially increases the risk of food
borne diseases caused by a wide variety of pathogens. There are different sources
of microbial invasion of street-vended foods. Pathogens may invade the interior
surfaces of the food during peeling, slicing, handling, trimming and other processes
like packaging, storing and marketing (Barro et al.,
Vendors-sold foods usually make use of simple facilities like wheel barrows,
trays, mats, tables and make-shift stalls, thus further increasing the risk
of food contamination. Contamination from raw materials and equipments, additional
processing conditions, improper handling and prevalence of unhygienic conditions
contribute substantially to the entry of bacterial pathogens (Mahale
et al., 2008). The present study was aimed at examining the microbiological
quality and safety of street foods like panipuri and bhelpuri sold at different
parts of Bangalore city in India.
MATERIALS AND METHODS
The present study was conducted during the period from 27.10.2009 to 11.01.2010 at Genohelix, Centre for Excellence in Biotechnology, Jain University, Chamarajpet, Bangalore, Karnataka, India.
All the media used during the course of the study were obtained from Himedia Laboratories Pvt. Limited (A- 406, Bhaveshwar Plaza, Mumbai-400086, India).
Collection of samples: Four locations in Bangalore city, India, were chosen for the collection of samples. Samples of panipuri and bhelpuri were picked up from at least two shops in each zone where the sale was maximum per day. All the samples were aseptically collected in sterile containers, stored at 4°C and analyzed within an hour of procurement. Samples were removed aseptically for pH measurement using pH meter.
Isolation and enumeration of microorganisms: Isolation and enumeration
of microbes were performed using serial dilution and spread plate technique.
One gram of the street food sample was properly homogenized using a sterile
mortar and pestle. One milliliter of the resultant homogenate was added to 9
mL of sterile 0.85% saline in a test tube and diluted serially to obtain dilutions
upto 10-5. For bacterial isolation 0.1 mL of the appropriate dilution
from each tube was aseptically pipetted out and plated onto different selective
and differential media (Tryptone Glucose Yeast Extract agar, MacConkey agar,
Deoxycholate Citrate agar, Salmonella Shigella agar, Thiosulphate Citrate
Bile Sucrose agar, Eosin Methylene Blue agar, Cetrimide agar, Baird Parkers
agar, Blood agar and Hichrome UTI agar) using the spread plate technique. All
the bacterial plates were incubated in an inverted position under aerobic conditions
at 37°C for 24 to 48 h. The fungal isolation was done on Potato Dextrose
agar and Sabouraud Dextrose agar. The plates were incubated at 27°C for
3 to 5 days. For bacterial enumeration the plates were used to determine the
number of colony forming units (cfu) per gram of food sample.
Identification and characterization of microbial isolates: Following
incubation, the isolated colonies were pure cultured and Gram stained. Biochemical
characterization of the isolated colonies was carried out using standard protocols
(Kannan, 2002). Identification was carried out according
to Bergeys Manual. Identification of the fungal isolates was performed
by lactophenol cotton blue staining and observation of macroscopic and microscopic
A total of eight samples of panipuri and bhelpuri were examined in this study.
The samples collected aseptically in sterile containers at a temperature of
32°C, showed pH varying between 3.4 and 4.0. Among the samples tested, majority
of them revealed pathogenic contamination with faecal coliforms. Bacterial enumeration
revealed a high count of faecal coliforms and faecal streptococci in all the
tested samples indicating poor bacteriological quality of the chaats. The significant
results of bacterial enumeration have been presented in Table
1. Total viable counts of bacteria in all the samples varied between 0.4-3x104
cfu g-1, faecal coliforms between 0.03-0.14x104 cfu g-1
and faecal streptococci between 0.2-11x104 cfu g-1.
||Enumeration of pathogenic bacteria (x 104 cfu g-1)
encountered in street-vended panipuri and bhelpuri in Bangalore city, India
|a: Total viable counts
||Bacterial colonies on Tryptone Glucose Yeast Extract agar
||Bacterial colonies on Hichrome UTI agar; E, E. coli;
K, Klebsiella sp.; S, Streptococcus faecalis
Total viable counts were enumerated on Tryptone Glucose Yeast Extract agar
as shown in Fig. 1.
Based on the growth on selective and differential media and biochemical tests,
various bacterial isolates were identified as Escherichia coli, Klebsiella
sp. and Streptococcus faecalis. Figure 2 represents
the selective isolation of Escherichia coli, Klebsiella sp. and
Streptococcus faecalis on Hichrome UTI agar as identified by the differential
pigmentation produced by the colonies. The morphology of the faecal streptococci
was studied by Grams staining as depicted in Fig. 3.
Coagulase-positive Staphylococcus aureus and Bacillus sp. were
also isolated from different samples of the street-foods as revealed by the
microscopic observations of the Gram stained preparations in Fig.
4 and 5, respectively.
||Y, yeasts; S, Streptococcus faecalis
Detection of Pseudomonas sp. in the food samples also implied the
insanitary quality of these street-vended foods. Salmonella and Vibrio
cholerae were not encountered in any of the samples.
Colonies of acidophilic yeasts were isolated on Sabouraud Dextrose agar as
depicted in Fig. 6. Based upon macroscopic and microscopic
characteristics, yeast isolates obtained from the street-vended chaats were
identified as Saccharomyces sp. (Fig. 6, 7).
Among the filamentous fungal forms isolated on Potato Dextrose agar, Mucor
sp. and Rhizopus sp. were identified as shown in Fig. 8
and 9, respectively.
||Gram positive bacilli arranged in chains
||Colonies of yeasts on Sabouraud dextrose agar
Different opportunistic and obligate bacterial pathogens and aciduric yeasts
and moulds were isolated from panipuri and bhelpuri sold by street vendors.
Low pH and high temperature (above 28°C) favoured the growth of facultative
acidophiles and neutrophiles, thus reducing the shelf life of street foods.
In the present investigation, all the samples showed occurrence of high bacterial
loads consisting of faecal coliforms and faecal streptococci. Bacterial enumeration
revealed a total viable count of 0.4-3.0x104 cfu g-1.
The presence of these microbes in food can be linked to a number of factors
such as improper handling and processing, use of contaminated water during washing
and dilution, cross contamination from rotten fruits and vegetables, or the
use of dirty processing utensils like knife and trays (Bryan
et al., 1992a; Khalil et al., 1994).
This might also implicate the processing and rinsing water as possible sources
of contamination of panipuri sold by street vendors (Nwachukwu
et al., 2008).
Among the different bacterial pathogens isolated in the present study E.
coli and Streptococcus faecalis showed the highest counts of 0.03-
0.14x104 cfu g-1 and 0.2-11x104 cfu g-1,
respectively, followed by Staphylococcus aureus and Bacillus sp.
(Table 1). The high frequency of isolation of E. coli (Fig.
1, 2) and Streptococcus faecalis (Fig.
2, 3), which are faecal and non faecal indicators of water
pollution respectively, indicated faecal contamination of the processing water
resulting in poor bacteriological quality of the chaats. Our findings are in
perfect correlation with the previous reports of high incidences of total faecal
coliform counts and coagulase positive S. aureus encountered in street-vended
fruit chaats in Patiala city (Kumar et al., 2006).
Previous investigations performed by Mahale and coworkers also reported the
isolation of E. coli and coagulase positive S. aureus from street-vended
fruit juices from Mumbai City, India (Mahale et al.,
The results of the present study are in agreement with those reported by Sheth
and coworkers (Sheth et al., 2005) which revealed
the presence of high Aerobic Mesophilic Colony Count (AMCC) and Staphylococcus
aureus counts along with the presence of Escherichia coli in bhelpuri
samples from urban Vadodara. The presence of coagulase-positive Staphylococcus
aureus in the chaats (Fig. 4) with a count of 0.01-0.8x104
cfu g-1 might be explained by the fact that it forms the normal microflora
present on/in several parts of the human body (Nester et
al., 2001).This can be introduced into the street foods during handling,
processing or vending.
The isolation of Bacillus sp. from panipuri and bhelpuri samples (Fig.
5) implicated the ubiquitous nature of bacterial spores especially in dusty
road side locations. The mesophilic spore-formers might have been introduced
into the prepared food due to the use of contaminated puffed-rice used in preparation
of bhelpuri. The prevalence of these mesophilic bacilli, showing a count of
0.01-0.9x104 cfu g-1 in the street-vended foods, could
also be explained by the fact that the ingredients such as wheat and rice flour
used in preparation of these Indian chaats generally contain spores of Bacillus
(Frazier and Westhoff, 2005). In general, the presence
of mesophilic spore-formers Bacillus cereus in food is of great significance
since this organism produces heat-sensitive (diarrheal) and heat- stable (emetic)
toxins associated with food poisoning (Bryan et al.,
1992b). Similar findings by Hanashiro suggested that 35% of the selected
street food samples from a restricted area of São Paulo city, Brazil
were considered unsuitable for consumption due to higher load of B. cereus
(Hanashiro et al., 2005). Staphylococcus
and Bacillus normally exhibit tolerance to a wide range of temperature
and pH, which justifies the presence of these bacteria even at highly acidic
The presence of respiratory pathogen such as Klebsiella in panipuri water might be attributed to the bacterial aerosols generated due to sneezing and coughing in public places. Handling of soiled notes and currencies by the street-food vendors might also act as vector for transmission of Pseudomonas into the panipuri water.
Many a times the street foods are sold by unlicensed vendors with poor education
level and untrained in food hygiene (Muinde and Kuria, 2005;
Barro et al., 2006). Cross- contamination of
street foods is also increased by unsanitary processing and preservation. The
use of dirty utensils, as well as the open display of street foods encourages
visits by flies, cockroaches, rodents and dust (Bryan et
al., 1992b). Preservation of prepared foods that requires no further
processing before consumption, at ambient temperatures during retail, maintenance
of the food at optimum temperatures, allow the invasion by pathogenic mesophiles
(Muinde and Kuria, 2005).
The organisms isolated might cause diseases that vary in severity from mild
gastroenteritis to severe and sometimes chronic or opportunistic infections
including food poisoning. Overall, the results of this study indicated that
street foods like panipuri and bhelpuri sold in many parts of Bangalore city
showed contamination with faecal coliforms and faecal streptococci. One major
source of contamination of foods sold by street vendors is the washing and processing
water (Khalil et al., 1994). It is contended
that contamination is mainly due to poor quality of water used for dilution
as well as prevailing unhygienic condition related to improper washing of fruits,
vegetables and utensils, inadequate storage of these at ambient temperatures
in unhygienic places, maintenance of premises and personal hygiene by vendors.
In addition, the presence of surface microflora of fruits and vegetables including
yeasts and moulds, use of unhygienic dusty surroundings, often swarming with
flies and fruit flies, other insects and airborne dust, mixing of rotten portions
with fresh stock and serving the prepared foods in filthy covers can also act
as potential sources of contamination. Sweet chutney (syrup) used in the preparation
of bhelpuri and panipuri might act as a chief source of osmophilic yeasts such
as Saccharomyces (Fig. 3, 6 and
7) and certain molds such as Mucor (Fig.
8) and Rhizopus (Fig. 9). Similar observations
have been reported by Frazier and Westhoff (2005). The
prevalence of various mold forms in Indian chaats could also be attributed to
the practice of mixing inadequately washed grated fruits and vegetables as important
ingredients in these foods.
The location of street-vended food stalls by the side of a dusty road with heavy vehicular traffic (air borne particles) and overcrowding (bus station and market) seems to add contamination. Such locations should be avoided for establishing the food stalls. In order to minimize the contamination level of foods, better hygiene is necessary. However, proper sanitary conditions must also be practised by the food vendors. Regular monitoring of the conditions of street-foods and better surveillance on the activities of street-food vendors must be introduced to minimize the risk of disease outbreaks associated with the consumption of street-foods like panipuri and bhelpuri.
Authors wish to extend their sincere gratitude to Dr. Chenraj Jain, Chairman, Jain Group of Institutions, Bangalore, for providing them with the financial and laboratory facilities required for this research work. Authors also wish to thank all the faculties and the entire supporting staff of the laboratory whose help has been invaluable for the successful completion of the research work.