Report of the Greater Manchester/Lancashire/PHLS Liaison Group Survey on
the Microbiological Examination of Conveyor Belts in Supermarkets
K. Williamson, G. Allen, F. J. Bolton, PHLS North West FESL – Preston PHL.
Date of Report, October 2000
Survey Code No. 004001
Introduction
Previous local surveys on microbiological contamination of the outer packaging of
prepacked fresh chicken demonstrated the presence of Campylobacter spp in 8%
(Lancashire FOG, 1996) and 5.8% (Lancashire FOG/Greater Manchester FLG, 1999,
Survey No. 904015). These surveys recommended further studies of surfaces that
may become contaminated with Campylobacter spp either from the outer packaging
or leakage from raw products.
A wide variety of foods both raw and ready to eat are carried on supermarket
checkout conveyor belts, hence the purpose of this survey was to determine the
microbiological quality and to assess the cleaning and hygiene control of conveyor
belts.
Because this survey involved sampling procedures within normal business hours,
permission was initially obtained from supermarket head offices and co-operation and
approval was confirmed with store managers.
Materials and Methods
Sample Collection
This survey was carried out as part of the Greater Manchester FLG/Lancashire
FOG/Preston PHL sampling programme during January – June 2000. Conveyor belt
surface samples were taken from three belts in current use, chosen at random from
each supermarket visited. Supermarkets included in the survey are listed in Appendix
1. The stores were visited without prior warning, and samples were taken according
to a standard protocol (Appendix 2). Two swabs were moistened in buffered peptone
water (BPW) and a random area of belt was vigorously swabbed. One swab was
placed into Campylobacter enrichment broth (CEB), and the other in BPW. Both
containers were placed in food grade bags, sealed and transported to Preston PHL in
coolboxes maintained at <5°C. Information relating to the premises and conveyor
belt cleaning practices was obtained by observation and enquiry and recorded on a
standard questionnaire (Appendix 3).
Microbiological examination
A total of 655 conveyor belt surfaces were swabbed and examined from 219
supermarket visits. The samples were submitted from 23/26 authorities in Greater
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Manchester and Lancashire as detailed in Appendix 4, and examined for the presence
of Salmonella and Campylobacter and enumeration of E. coli.
Results
Microbiological results
Table 1. Microbiological results of conveyor belt surfaces (n = 655)
Detected/sample
E. coli
Salmonella
Campylobacter
Not
detected/sample
<40cfu/sample
655
0
0
655
655
Questionnaire results
Questionnaire results are listed below but were not analysed in relation to
microbiological quality due to all results being satisfactory.
Q.1.
How many checkouts are there? (n = 219)
1-5
75 (34%)
Q.2.
11-15
28 (13%)
16-20
15 (7%)
>20
40 (18%)
Are bags available to the customer at point of fresh raw meat/poultry
display? (n = 180)
Yes
73 (41%)
Q.3.
6-10
61 (28%)
No
107 (59%)
Appearance of belts at checkouts:
Checkout
A(n=214)
B(n=214)
C(n=214)
Total (n=642)
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Clean
181 (85%)
175 (82%)
168 (79%)
524 (82%)
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Wet
3 (1%)
5 (2%)
5 (2%)
13 (2%)
Soiled
30 (14%)
34 (16%)
41 (19%)
105 (16%)
Q.4.
Who cleans the belts? (n=219)
Contract cleaners
37 (17%)
Q.5.
Once per day
173 (80%)
Twice per day
20 (9%)
Other
24 (11%)
Are the belts cleaned immediately if the belt appears:
Wet (n=211)
Soiled (n=207)
Breakage/spill (n=211)
Q.7.
Both
29 (13%)
How often are the belts cleaned? (n=217)
Never
0
Q.6.
Supermarket staff
153 (70%)
Yes
208 (99%)
202 (98%)
210 (99.5%)
No
2 (1%)
5 (2%)
1 (0.5%)
Are cleaning materials available at: (n=214)
Every checkout
Every other checkout
Other*
Other
54 (25%)
20 (9%)
140 (65%)
114 (53%)
* NB. The majority were readily available from a storeroom or cleaners room
Q.8.
What cleaning agent is used (n=197)
Detergent
60 (30%)
Q.9.
Sanitiser
97 (49%)
Detergent/disinfectant
24 (12%)
Disinfectant
9 (5%)
Window cleaner
7 (4%)
How is the cleaning agent stored at the point of use? (n=191)
Spray
138 (72%)
Container
37 (19%)
Wipe
16 (8%)
Q.10. How often is the cleaning cloth disposed? (n=213)
Each time used
133 (62%)
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Daily
40 (19%)
>Daily
24 (11%)
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Not known
16 (8%)
Conclusions
(1)
In relation to the indicator and pathogen organisms investigated, the
microbiological quality of conveyor belt surfaces was considered excellent.
There was no evidence of transfer and/or survival of Salmonella,
Campylobacter or E. coli on the belt surface.
(2)
The results of the questionnaire indicated good hygiene practices associated
with conveyor belt cleaning e.g. frequency, appearance, spillage, etc.
(3)
The potential for cross contamination from the outer packaging of raw poultry
has been established (Survey No. 904015). Leakage from raw products
particularly frozen poultry on thawing (Survey 004006) may also be a
potential source of pathogen transfer. Hence the provision of bags at raw
meat/poultry display for customer use is considered good practice and
recommended. However the provision of bags was only observed, during
73/180 (41%) of supermarket visits.
Future work

Further surveys relating to potential sources of Campylobacter in retail outlets.

Future sampling points need to be identified for investigation i.e. shopping
trolleys/baskets, shelving.
Acknowledgements
The authors would like to thank Alan Walker (Preston) and particularly Kathryn Beryl
(Oldham) for their assistance in producing the questionnaire and protocol, and for
their support and advice.
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APPENDIX 1
LIST OF PARTICIPATING SUPERMARKETS: -
Co-operative Retail Services Ltd
United Norwest Co-operative Ltd
Somerfield Stores Ltd
Safeway Stores PLC
Iceland Frozen Foods PLC
Aldi Stores
Tesco Stores Ltd
Marks and Spencer PLC
Lidl UK
Wm. Morrisons Supermarkets PLC
Sainsbury’s Supermarkets Ltd
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APPENDIX 2
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APPENDIX 3
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APPENDIX 4
A total of 655 samples were received from 23 out of the 26 authorities in Greater
Manchester and Lancashire
Authority
Number of supermarket
visits
Number of samples
received
Barrow
Blackburn
Blackpool
Bolton
Burnley
Bury
Chorley
Fylde
Hyndburn
Lancaster
Manchester
Oldham
Pendle
Preston
Ribble Valley
Rochdale
Rossendale
Salford
South Lakes
South Ribble
Stockport
Tameside
Trafford
West Lancs
Wigan
Wyre
0
0
11
10
12
13
12
12
5
6
10
10
0
14
5
8
8
12
4
4
6
12
11
12
10
12
0
0
33
30
36
39
35
36
13
18
30
30
0
42
15
24
24
36
12
12
18
36
34
36
30
36
TOTAL
219
655
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