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Advances in Environmental Biology, 7(1): 177-181, 2013
ISSN 1995-0756
This is a refereed journal and all articles are professionally screened and reviewed
ORIGINAL ARTICLE
Bacteria Commonly Associated with Bakery Equipments in Selected Areas Around
Olabisi Onabanjo University Environ, Ago – Iwoye, Nigeria.
1
Adesetan, T.O., 1Ilusanya, O.A.F., 2Sobowale, A.A. and 1Jamani, U.P.
1
Department of Microbiology, Olabisi Onabanjo University, PMB 2002, Ago- Iwoye, Ogun State, Nigeria.
Department of Plant Science and Applied Zoology, Olabisi Onabanjo University, PMB 2002, Ago- Iwoye,
Ogun State, Nigeria.
2
Adesetan, T.O., Ilusanya, O.A.F., Sobowale, A.A. and Jamani, U.P.; Bacteria Commonly Associated
with Bakery Equipments in Selected Areas Around Olabisi Onabanjo University Environ, Ago –
Iwoye, Nigeria.
ABSTRACT
Research was carried out to identify the bacteria associated with equipments used in bread bakeries. Sterile
swabs sticks were used to take a total of 78 samples from pre-baking and post-baking equipments surfaces viz.,
cutting machine (1), millers (5), mixers (5), scales (3), tables (5) and baking pans (20) from five selected bread
bakeries across Ago – Iwoye, a town densely populated with tertiary institution students and examined for
bacterial contamination. Cultural characteristics and biochemical tests were carried out on pure cultures of
isolates for identification purposes. Three genera of bacteria were identified, viz., one gram positive cocci and
two gram positive bacilli. They were Staphylococcus aureus, Bacillus subtilis and B. cereus. 66.7% of the
equipments were contaminated with S. aureus, 14.1% with B. subtilis, 7.7% with B. cereus and 11.5% had no
bacterial growth. Strict hygienic practice should be observed when handling these equipments to guard against
food poisoning.
Key words: bread, bakery equipments, S. aureus, B. subtilis, B. cereus
Introduction
Bread is a staple food consumed by most people
in Nigeria. Locally made bread prepared in Ago Iwoye town, Ogun State, Nigeria is consumed mostly
by tertiary students residing in the town. The locally
made bread is prepared by cooking a dough of flour
and water, salt, fat and leavening agents such as yeast
and baking soda.
The surface of a freshly baked loaf of bread is
practically free of viable microorganism but is
subject to contamination by mold spores from the air
during cooling and before wrapping. During slicing,
contamination may take place from microorganisms
in the air, on the knives, or on the wrapper. Spores of
bacteria able to cause ropiness in bread will survive
the baking process [9].
The occurrence of pathogenic microorganisms
has always been attributed to several factors, which
include contamination through water, soil, food
processing equipments, food contact surfaces and
most importantly food handlers [1,11]. Improper
handling of food is responsible for most cases of
food borne diseases and intoxication, including
improper use of preparation and storage temperature,
cross contamination and poor personal hygiene [10].
When food handlers do not practice proper personal
hygiene or correct food preparation, they may
become vehicles for microorganisms, through their
hands, mouth, skin among others [6,18]. There are a
number of important sources of microbiological
contamination in any food manufacturing operation,
but most microbiologists would probably rank
people, raw materials and processing water as their
top three [15].
All types of flour, especially wheat flour, are
contaminated with Bacillus spores as a result of soil
contamination [14,15], cultivation and processing
methods [8,24]. Other origins of the Bacillus
contamination have been reported to be raw materials
and bakery equipment [3,16]. Staphylococcus species
are found in a broad range of commercial foods,
including meat and meat products, poultry and egg
products, salads, bakery products, sandwich fillings,
milk and dairy products. Food products that require
considerable handling during preparation or are kept
at slightly elevated temperatures after preparation are
frequently involved in staphylococcal food poisoning
[4]. Most species of staphylococci can produce some
form of enterotoxin, the causative agent of
staphylococcal enteritis
Corresponding Aauthor:
Adesetan, T.O., Department of Microbiology, Olabisi Onabanjo University, PMB 2002, AgoIwoye, Ogun State, Nigeria.
E-mail: titilayoronke@yahoo.com
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Adv. Environ. Biol., 7(1): 177-181, 2013
Materials and Methods
agar. Blood Agar was prepared by allowing sterilized
nutrient agar cool to 45°C and 5% sterile defibrinated
sheep blood was aseptically added, mixed and
poured into Petri dishes to set.
Collection of Samples:
Bacterial characterization:
Samples were collected from five different
bakeries. Sterile swab sticks were used to collect
samples from the surfaces of several pre-baking and
post-baking equipment surfaces viz., cutting
machine, miller, table, mixer, scale and different
baking pans. The samples were transported to the
laboratory immediately after collection. The bakeries
were coded BA1- BA5
In bakery BA1; 18 samples were collected from
pre-baking and post-baking equipments which
include 4 baking pans each. In bakery BA2; 14
samples were collected from pre-baking and postbaking equipments which include 4 baking pans
each. In bakery BA3; 16 samples were collected from
pre-baking and post-baking equipments which
include 4 baking pans each. In bakery BA4; 16
samples were collected from pre-baking and postbaking equipments which include 4 baking pans
each. In bakery BA5; 14 samples were collected from
pre-baking and post-baking equipments which
include 4 baking pans each.
Representative colonies of isolates resulting
from the isolation were sub cultured and preserved
on nutrient agar slant. Cultural characteristics of the
isolates on the plates were noted. The organisms
were identified based on Bergey’s manual of
determinative bacteriology (Buchanan and Gibbons,
1974).
The aims of this research work are to isolate and
identify bacterial from selected bakery equipments.
Isolation of Bacteria:
The streak plate method was used for isolation.
The sterile swab sticks were dipped in saline water
and then used to streak the surface of already
solidified agar. The media used for isolation were
Nutrient agar (Oxoid, UK CM0003B) and Blood
Results:
Biochemical characterization:
Three species of bacteria were isolated and these
are Staphylococcus aureus, Bacillus subtilis and
Bacillus cereus.
Incidence of bacteria in bakery equipment:
The single cutting machine, mixers, tables in
bakeries BA1 and BA2 and scales from bakeries BA1
and BA3 analyzed were contaminated with S. aureus.
No bacteria were isolated from the scales in bakery
BA4. Thirteen baking pans were contaminated with
S.aureus, 3 with B. subtilis, 3 with B. cereus and no
growth in 1 before (pre) baking; 16 with S. aureus
and 4 with B. subtilis after baking (post baking). In
bakery BA3 all the baking pans were contaminated
with B. subtilis after (post) baking (Tables 1 and 2).
Table 1: Incidence of bacteria isolates on bakery equipments before baking (pre-baking).
Equipment
No sampled
S. aureus
B. cereus
B. subtilis
Cutting machine
1
2.6% (1)
Mixer
5
7.7% (3)
2.6% (1)
2.6% (1)
Miller
5
7.7% (3)
2.6% (1)
Tables
5
5.1% (2)
2.6% (1)
Scale
3
5.1% (2)
Baking pan
20
33.3%(13)
7.7% (3)
7.7% (3)
Total
39
61.5%
12.9%
12.9%
No growth
2.6%(1)
5.1%(2)
2.6%(1)
2.6%(1)
12.9%
Table 2: Incidence of bacteria isolates on bakery equipments after baking (post-baking).
Equipment
No sampled
S. aureus
B. cereus
Cutting machine
1
2.6% (1)
Mixer
5
7.7% (3)
2.6% (1)
Miller
5
7.7% (3)
Table
5
7.7% (3)
Scale
3
5.1% (2)
Baking pan
20
41.0%(16)
Total
39
71.8%
2.6%
No growth
2.6%(1)
5.1% (2)
2.6% (1)
12.9%
Incidence of bacteria in bakery equipments before
and after baking:
B. subtilis
2.6%(1)
2.6% (1)
10.3%(4)
15.5%
contamination after baking.
Incidence of bacteria in each bakery:
Figure 1 show there was an increase in
contamination by S. aureus and B. subtilis after
baking. There was drastic reduction in B. cereus
Figure 2 shows the rate of occurrence of bacteria
isolates in each bakery. All the bakeries are
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contaminated with at least two species of bacteria
except bakery BA4 that was contaminated with S.
aureus only. All the bakeries are contaminated with
S. aureus with BA1 having the highest value.
Fig. 1: Incidence of bacteria in bakery equipments before and after baking.
Fig. 2: Incidence of bacteria in each bakery.
Discussion:
Isolation of Staphylococcus aureus, Bacillus
subtilis and Bacillus cereus from bakery equipments
conforms to the work of (Viljoen and Von Holy,
1997) that isolated Bacillus species from equipment
surfaces, air, raw materials, and hands of workers,
and (Nasir and Islam, 2007) who isolated Bacillus
and Staphylococcus from bakery foods in
Bangladesh. Bacillus species was also isolated from
flour and ropy bread as the main species involved in
bread spoilage (Sorokoluva et al., 2003) and reported
the source of contamination to be from raw materials
and bakery equipment. Toxigenic B. cereus has been
isolated from Nigeria flour based foods (Yusuf et al.,
1992).
S. aureus was isolated from most of the
equipments with 66.7% occurrence, followed by B.
subtilis with 14.1%, B. cereus 7.7% while 11.5% had
no growth. From the work of (13) Bacillus has
84.62% while Staphylococcus has 76.92%. This
shows that Bacillus and Staphylococcus are the
bacteria frequently encountered in bakery products
and equipments.
There was high increase in S. aureus and a little
increase in B. subtilis contamination after baking.
According to Bremer et al. (2004), the presence of S.
aureus on the surfaces of equipment after production
could be as a result of recontamination by food
handlers. Food handlers are usually the main source
of food contamination. However, the surfaces of
equipment can also be a source of S. aureus
contamination. Staphylococci exist in air, dust,
sewage, water, milk, and food or on food equipment,
environmental surfaces, humans, and animals.
Humans and animals are the primary reservoirs.
Staphylococci are present in the nasal passages and
throats and on the hair and skin of 50% or more of
healthy individuals. Although food handlers are
usually the main source of food contamination in
food poisoning outbreaks, equipment and
environmental surfaces can also be sources of
contamination with S. aureus.
It was observed during sampling that the
bakeries were not carrying out proper hygiene
practices, their equipments were rarely covered
(often exposed) and prior to the baking process,
equipment are not properly cleaned; a knife used as
cutter is also used to scrape off the residue of dough.
The bakery environments were dusty and unkempt:
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Adv. Environ. Biol., 7(1): 177-181, 2013
an evidence of lack of regular and proper cleaning.
This fact could explain the high rate of
Staphylococcus aureus found in these bakeries.
However, bakery BA3 showed a high number of
Bacillus subtilis, which could have been from the
raw material. The ability of Bacillus species to resist
dessication allows their survival on dried products
such as cereal and flours. B. cereus is widely
distributed in the environment and can be isolated
from soil, water and vegetation [2].
B. subtilis is a notable food spoiler, causing
ropiness in bread and related food. Ropy bread or
rope is a bacterial spoilage condition of bread
[23,12]. A major source of Bacillus contamination is
from raw ingredients [23] so ideally it would thus be
profitable for bakeries to use only ingredients with
low levels of contamination.
In conclusion, vegetative bacteria, as well as,
moulds and viruses, are readily destroyed during
baking, but post-baking contamination from air,
equipment and handlers can occur [7]. Due to the
high incidence of S. aureus carriage by humans,
prevention of staphylococcal food poisoning relies
on good hygienic practices to reduce the incidence of
contamination of food by food handlers. It can thus
be concluded from this study that the high
occurrence of Staphylococcus aureus as related to
bakery equipment contamination is as a result of
food handlers which are usually the main source of
food contamination. Surfaces of equipment can also
be a source of S. aureus.
Staphylococcus aureus and Bacillus species, the
bacteria found in or on the bakery equipments can be
eliminated by proper hygienic practices and abiding
by rules and regulations as laid down by the
legislative bodies.
7.
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