Food
safety control aims to safeguard
public health and provide assurance
on food safety. To this end, microbiological
analyses are useful ways to assess
the safety and quality of food
involved. This paper presents
the recommended microbiological
guidelines for ready-to-eat food.
Scope
of the Guidelines
2. In
the Hong Kong Special Administrative
Region, the legal powers and instruments
for the enforcement of microbiological
safety of food are provided for
in the Public Health and Municipal
Services Ordinance, Cap. 132.
Section 54 stipulates that it
is an offence to sell food that
is unfit for human consumption.
General protection for purchasers
of food is provided in Section
52 of the Ordinance when the food
is not of the nature, substance,
quality of the food demanded by
the purchaser.
3. For
enforcement purposes, microbiological
limits are specified which are
also used for assessment of microbiological
safety and monitoring of food
. This set of recommended microbiological
guidelines for ready-to-eat food
provides operational support for
food safety monitoring and control.
Definition
and Interpretation
4. Microbiological
Guidelines are criteria indicating
the microbiological condition
of the food concerned so as to
reflect its safety and quality.
They can be introduced to the
food industry to observe voluntarily
or stipulated in legislation for
compliance.
5. "Ready-to-eat"
is defined as the status of the
food being ready for immediate
consumption at the point of sale.
It could be raw or cooked, hot
or chilled, and can be consumed
without further heat-treatment
including re-heating.
6. "Aerobic
colony count (ACC)" is a count
of viable bacteria based on counting
of colonies grown in nutrient
agar plate. This is commonly employed
to indicate the sanitary quality
of foods. The incubation condition
of ACC used in this guideline
is 30¢XC for 48 hours.
7. "Indicator
organism" refers to the selected
surrogate markers. The main objective
of using bacteria as indicators
is to reflect the hygienic quality
of food. E. coli is commonly
used as surrogate indicator. Its
presence in food generally indicates
direct or indirect faecal contamination.
Substantial number of E. coli
in food suggests a general
lack of cleanliness in handling
and improper storage.
8. "Specific
pathogens" refer to bacteria that
may cause food poisoning. Mechanisms
involved may be toxins produced
in food or intestinal infection.
The symptoms of food poisoning
vary from nausea and vomiting
(e.g. caused by S. aureus),
through diarrhoea and dehydration
(Salmonella spp. and Campylobacter
spp.) to paralysis and death in
the rare cases of botulism. The
infectious doses vary from less
than 10 to more than 106
organisms.
Components
of Microbiological Criteria
9. The
microbiological limits of this
set of guidelines are organized
under the following three components:
Aerobic
Colony Count;
Indicator
Organisms - E. coli count
is the only indicator organism
included; and
Specific
Food Poisoning Pathogens -
nine specific bacterial pathogens
are included in this set of
guidelines.
10. For
assessment of hygienic quality,
food items are grouped into five
categories taking into account
the raw ingredients used, and
the nature and degree of processing
before sale. The categorization
is summarized in the Food
category table for ACC assessmentin the Annex.
Classification
of Microbiological Quality
11. The
microbiological assessment of
ready-to-eat food on the above
three components will lead to
the classification of the food
quality into one of the following
four classes.
Class A:
the microbiological status
of the food sample is satisfactory.
Class B:
the microbiological status
of the food sample is less
than satisfactory but still
acceptable for consumption.
Class C:
the microbiological status
of the food sample is unsatisfactory.
This may indicate a sub-optimal
hygienic conditions and microbiological
safety levels. Licensees of
food premises should be advised
to investigate and find out
the causes and to adopt measures
to improve the hygienic conditions.
Taking of follow-up samples
to verify the improvement
may be required.
Class D:
the microbiological status
of the food sample is unacceptable.
The food sample contains unacceptable
levels of specific pathogens
that is potentially hazardous
to the consumer. In addition
to giving advice to the licensee
of the food premises as stated
in (c) above, warning letters
as well as other enforcement
actions should be considered.
Table
of Microbiological Limits
12. Microbiological
limits in respect of the above
components, and the associated
microbiological quality of the
food samples concerned are summarized
in the following table.
Microbiological
Limits for Assessment of Microbiological
Quality of Ready-to-Eat Foods
Criterion
Microbiological
quality
colony-forming
unit (cfu) per gram unless
specified
Class
A
Satisfactory
Class
B
Acceptable
Class
C
Unsatisfactory
Class
D
Unacceptable
Aerobic
colony count (ACC) [30¢XC/48
hours]
Food
Category
(see
table next page)
1
<
103
103
¡V < 104
>
104
N/A
2
<
104
104
¡V < 105
>
105
N/A
3
<
105
105
¡V < 106
>
106
N/A
4
<
106
106
¡V < 107
>
107
N/A
5
N/A
N/A
N/A
N/A
Indicator
organisms (apply to all
food categories)
E. coli (total)
<
20
20 ¡V < 100
>
100
N/A
Pathogens
(apply to all food categories)
Campylobacter spp.
Not
detected in 25g
N/A
N/A
Present
in 25g
E. coli O157
Not
detected in 25g
N/A
N/A
Present
in 25g
L.
monocytogenes
Not
detected in 25g
N/A
N/A
Present
in 25g
Salmonella spp.
Not
detected in 25g
N/A
N/A
Present
in 25g
V. cholerae
Not
detected in 25g
N/A
N/A
Present
in 25g
V. parahaemolyticus
<
20
20
¡V < 100
100
¡V < 103
>
103
S. aureus
<
20
20
¡V < 100
100
¡V <104
>
104
C. perfringens
<
20
20
¡V < 100
100
¡V <104
>
104
B. cereus
<
103
103
¡V < 104
104
¡V < 105
>
105
N/A denotes "Not
applicable"
Annex:
Food Category Table for Aerobic
Colony Count Assessment
Cakes,
pastries, slices and desserts
¡V with dairy cream
Cakes,
pastries, slices and desserts
¡V without dairy cream
Cheesecake
Mousse
/ dessert
Tarts,
flans and pies
Trifle
3
2
5
1
2
3
Savoury
Bean
curd
Cheese-based
bakery products
Fermented
foods
Flan /
quiche
Dips
Mayonnaise
/ dressings
Samosa
Satay
Spring
rolls
5
2
5
2
4
2
2
3
3
Vegetable
Coleslaw
/ salads (with or without
meat)
Fruit
and vegetables (dried)
Fruit
and vegetables (fresh)
Rice
Vegetables
and vegetable meals (cooked)
3
3
5
3
2
Dairy
Cheese
Yoghurt
5
5
Ready-to-eat
meals
Pasta
/ pizza
Meals
(others)
2
2
Sandwiches
and filled rolls
With
salad
Without
salad
4
3
Sushi
& sashimi
Fish
fillet and fish roe sashimi
/ sushi
Sashimi
other than fish fillet and
fish roe
3
4
The Frozen Confection Regulations
and Milk Regulations under Cap
132 provide specification on the
microbiological quality of frozen
confections and milk and milk
beverages. The Milk Regulations
also include microbiological limits
for milk in its raw state.
Centre for Food Safety
Food and Environmental Hygiene
Department
Last revision date: 02-05-2006