Report of the Greater Manchester/Lancashire/PHLS Liaison Group Survey on
the Microbiological Examination of Ready to Reheat Delicatessen Meals in
Retail Food Outlets
K. Williamson, G. Allen, F. J. Bolton, PHLS North West FESL - Preston PHL
S. Clarke, Chorley EHD
Date of Report:
07/06/99
Survey Code No. 804023
Introduction
A number of retail outlets now provide ready to reheat meals in a ‘takeaway’ form. The purchasers
can choose from a range of bulk foods on display which are then served into containers for taking
home and reheating by the customer. Since this type of product is becoming more widely available
it was decided to determine the microbiological quality of ready to reheat delicatessen meals. A
questionnaire (Appendix 1) relating to retailer, product, storage, serving and other hygienic practices
was analysed so that risk factors associated with microbiological quality could be identified. Other
factors including reheating instructions and shelf life were also examined.
Because this type of product is not ready to eat it is not included in the PHLS microbiological
guidelines for some ready to eat foods sampled at point of sale (1).
The survey aimed to provide recommendations including a microbiological guideline for this type
of product to EHO’s so as to assist them with their task of ensuring food safety.
Materials and Methods
Sample collection
Ready to reheat meals collected from retail outlets were examined at Preston PHL between January
- March 1999 according to a standardised protocol (Appendix 1). The samples included curry,
pasta, mousaka, stews and rice dishes. Prepacked ready meals from display shelves were
specifically excluded from this study. Samples were collected from supermarket delicatessen
counters, market stalls and branded grocers by staff from the Lancashire and Greater Manchester
Environmental Health Departments in accordance with the Food Safety Act 1990, Code of Practice
No. 7 (2).
Information relating to the premises, product, preparation and serving was obtained by observation
and enquiry, and was recorded on a standard proforma (Appendix 1).
Sample examination
The samples were examined for aerobic colony count (ACC) (30°C/48h), Enterobacteriaceae,
E. coli, Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Listeria spp and
Salmonella spp using UKAS accredited food methods.
Results
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A total of 262 ready to eat meals were submitted and examined from 25 out of the 26 authorities in
Greater Manchester and Lancashire as detailed in Appendix 1.
Microbiological results
The microbiological results are summarised in Table 1.
Table 1. Microbiology results of ready to reheat delicatessen meals (n = 262).
Detected
ACC
Enterobacteriaceae
E.coli
S.aureus
B.cereus
C.perfringens
Listeria spp
Salmonella spp
Not
detected
<10
<20
<102
10-<102
20-<102
24
112
50
3
-
258
258
258
260
1
258
0
2
102-<103
103-<104
104-<105
105-<106
106-<107
>107
28
50
4
4
1
2
56
23
-
72
17
1
-
35
9
-
27
-
20
1
-
262
The results were assessed using Categories 2, 3 and 4 of the PHLS microbiological guidelines for
some ready to eat foods (1) and the Preston PHL proposed guidelines for Enterobacteriaceae (3).
The results are summarised in Table 2.
Table 2.
Microbiological quality of ready to reheat delicatessen meals using Categories 2,
3 and 4 (2) and (3) (n = 262)
Category 2 applied
Category 3 applied
Category 4 applied
Table 3.
Satisfactory (%)
101 (39)
161 (62)
181 (69)
Borderline (%)
75 (29)
45 (17)
44 (17)
Unsatisfactory (%)
85 (32)
55 (21)
36 (18)
Unacceptable
1
1
1
Key to classification (1).
Microbiological
parameter
Aerobic Colony Count;
Food category 2
Food category 3
Food category 4
Enterobacteriaceae*
E. coli
S. aureus
B. cereus
Listeria spp.
C. perfringens
Salmonella spp.
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Microbiological quality (cfu/g unless stated)
Borderline - limit
Satisfactory
of acceptability
Unsatisfactory
<104
<105
<106
<5.0 x 102
<20
<20
<103
<20
<10
Not detected in
25g
104 - <105
105 - <106
106 - <107
5.0 x 102 - <104
20 - <102
20 - <102
103 - 104
20 - <102
10 - <102
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105
106
107
104
102 - <104
102 - <104
104 - 105
102 - <104
102 - <104
Unacceptable/
potentially
hazardous
N/A
N/A
N/A
N/A
104
104
105
104
104
Detected in 25g
N/A = Not applicable
*
= Preston PHL proposed microbiological guidelines (2)
From these results it is recommended that the PHLS guidelines for some ready to eat foods (1) and
in particular Category 3 for the ACC, and the Preston PHL proposed guidelines for
Enterobacteriaceae (3) should be used to assess ready to reheat delicatessen meals. Based on the
Category 3 guideline, 161 (62%) of the samples were satisfactory, 45 (17%) borderline, 55 (21%)
unsatisfactory and 1 (<1%) samples were of unacceptable quality. The ACC was the
microbiological parameter most often associated with unsatisfactory results accounting for 47 of the
56 unsatisfactory/unacceptable samples. The remainder (unsatisfactory results not due to ACC)
were caused by the presence of Enterobacteriaceae (4; 14%) in excess of 104 cfu/g, Staphylococcus
aureus (4; 14%) and Clostridium perfringens (1; 2%) in excess of 100 cfu/g. There was only one
unacceptable result due to a high level ( 104 cfu/g) of E. coli. This sample was also unsatisfactory
for ACC and Enterobacteriaceae.
Enterobacteriaceae at unsatisfactory levels i.e. at or greater than 104 cfu/g were present in 27 (10%)
samples. Low numbers of unsatisfactory results due Staphylococcus aureus, Bacillus cereus,
Clostridium perfringens and Listeria spp. were obtained as demonstrated in Table 1. Significantly
only one sample produced an unsatisfactory level of E. coli. Salmonella spp. was not detected in
any of the samples.
Questionnaire results
Questionnaire results were analysed in relation to microbiological quality when relevant. A copy of
the questionnaire is available in Appendix 1.
Q.1
The majority of samples, 227 (87%) were collected from supermarkets and 23% of these gave
unsatisfactory results, 61% satisfactory results. There were too few samples from other premises to
comment.
Q.2, Q.3
The majority of meals examined 165 (63%) were meat and 21% of these gave unsatisfactory results
and 61% gave satisfactory results. Eighty-nine vegetable meals including rice and pasta produced
22% unsatisfactory and 63% satisfactory results.
The main ingredient was indicated for 255 of the meals. Chicken was the most common meat
ingredient and was included in 97 samples (38%). These samples produced 29 (30%)
unsatisfactory and 48 (49%) satisfactory results. Rice was the most common non meat main
ingredient and was included in 63 samples (24%). These samples produced 15 (24%) unsatisfactory
and 36 (57%) satisfactory results.
Q.4
The majority (91%) of the meals were not made on the premises.
Q.5, Q.6
The majority (94%) of the bulk product was stored chilled, and 6% frozen.
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A dedicated fridge/freezer was used to store 80% of the meals. Of these 22% gave unsatisfactory
results and 60% were satisfactory. Of the 20% not stored in a dedicated fridge/freezer 22% gave
unsatisfactory results and 66% were satisfactory.
Q.7, Q.8, Q.9
Cleaning procedures for 257 display areas were checked and all were satisfactory and appeared
clean. The temperature of a relevant food product in 250 display units was recorded.
A total of 200 (80%) samples were collected form chill displays at <5°C. Of these 46 (23%) were
unsatisfactory and 117 (58%) satisfactory. Fifty (20%) samples were obtained from chill displays at
5-8°C. Of these 9 (18%) were unsatisfactory and 34 (68%) satisfactory. No food products were
found to be stored at >8°C in this study.
Q.10, Q.11, Q.16, Q.17
Information on the type of container used for display was available for all 262 samples. The
majority of samples (202: 77%) were in reusable containers and the remaining 60 (23%) were in
disposable containers.
Of the 202 samples in reusable containers 51 (25%) produced unsatisfactory and 106 (52%)
satisfactory results. Of the 60 samples in disposable containers, 4 (7%) produced unsatisfactory and
51 (85%) satisfactory results.
Most of the reusable display containers (192; 95%) were washed between display periods.
The same display container was used throughout the serving period at 62% of the premises visited.
Of these 20% produced unsatisfactory and 66% satisfactory results.
Of the 98 (38%) containers which were changed during the serving period 23% produced
unsatisfactory and 55% satisfactory results. Residual food in 55% of the display containers was
discarded at the end of the serving period. Of these (19%) produced unsatisfactory and 60%
satisfactory results.
Residual food in 45% of the display containers was not discarded at the end of the serving period.
24% of these produced unsatisfactory and 60% satisfactory results.
Q.12
The product shelf life following initial display was obtained for 244 samples and is summarised
below.
1 day
2 days
3 days
4 days
>4 days
59 (24%)
88 (36%)
45 (18%)
23 (10%)
29 (12%)
Q.13, Q.14, Q.15
Of the 141 (54%) of meals served in foil containers, 18% produced unsatisfactory results and 60%
satisfactory.
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Of the 43 (16%) meals served in polystyrene containers 26% produced unsatisfactory results and
63% satisfactory.
The majority, 96% of meals were served using dedicated utensils.
Information relating to delicatessen serving staff also handling raw foods was obtained for 255 staff.
Of these 70 (27%) also handled raw foods, and 183 (73%) did not.
Of the 70 staff who also handled raw food, 26% of the delicatessen meals produced unsatisfactory
results and 61% satisfactory.
Of the 185 staff who never handled raw foods, 20% of the delicatessen meals produced
unsatisfactory results and 61% satisfactory.
Q.18, Q.19, Q.20
The following information was obtained in relation to instructions given with the takeaway product.
Were reheating instructions provided? (n = 261)
Written
208 (80%)
Verbal
6 (2%)
None
47 (18%)
Were domestic storage instructions provided? (n = 261)
Written
139 (53%)
Verbal
3 (1%)
None
119 (46%)
Was a ‘use by’ time specified (n = 260)
Written
203 (78%)
Verbal
3 (1%)
None
54 (21%)
Conclusions
1.
Category 3 of the PHLS microbiological guidelines for some ready to eat foods (2) and the
Preston PHL proposed guidelines for Enterobacteriaceae (3) are recommended for assessing
the microbiological quality of ready to reheat delicatessen meals.
2.
Overall the microbiological quality of this type of product, sampled in the survey was good
with only one sample giving an unsatisfactory level of E. coli. The potential foodborne
pathogens, Staphylococcus aureus, Bacillus cereus, Clostridium perfrigens and Listeria spp
present in a small number of samples were all detected at <1000/g. Salmonella was not
detected in any of the samples.
3.
Hygiene practices associated with the meals sampled in this survey i.e. use of dedicated
storage conditions, display temperatures, dedicated serving utensils, cleaning procedures etc.
were good.
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4.
The use of disposable display containers produced meals of better microbiological quality
than those from the reusable containers. However, only 23% of the meals were stored in
disposable containers.
5.
A surprisingly high number of delicatessen serving staff also handled raw products (27%).
Meals served by these staff produced a higher number of unsatisfactory results than the
meals served by dedicated delicatessen staff.
6.
Consumer information was not provided with all of the meals. Reheating instructions were
not provided for 18% of the meals purchased, the use by date was not specified for 21% and
domestic storage instructions were not provided for 46% of the samples.
7.
The shelf life following initial display was  4 days for 22% of the products. The age of the
product was not specified in this survey and the conclusions are therefore drawn from
samples at different stages of their shelf life. It may be useful to carry out further studies on
ready to reheat meals 4 days after initial display.
References
(1)
PHLS. 1996. Microbiological guidelines for some ready-to-eat foods sampled at the point
of sale - an expert opinion from the PHLS. PHLS Microbiological Digest. 13: 41-43.
(2)
Ministry of Agriculture, Fisheries and Food. Department of Health, Food Safety Act 1990,
Code of Practice No. 7: Sampling for Analysis and Examination. 1990. London. HMSO.
(3)
Suggested guidelines for Enterobacteriaceae counts in food samples. G. Allen, F. J. Bolton,
K. Williamson Preston PHL. PHLS Annual Scientific Meeting September 1998, Poster
presentation.
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APPENDIX 1
No. of pages
(A)
Protocol
(1 - 3) Available on request
(B)
Questionnaire
(1)
(C)
Survey participants
(1)
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