Listeria

1
???????????????????????????????????????????????
???????????????????????
?????????????? ??.?????? ?????????? ??????????????
?????????? ?????????????? ?????????????????????
2
1. Risk
A function of the probability of an adverse
health effect and the severity of that effect,
consequential to a hazard (s) in food. (CAC, 1999)
3
2. Hazards
A biological, chemical or physical agent in, or
condition of, food with the potential to cause an
adverse health effect.
(CAC, 1999)
4
Hazards
Pathogen in condition/in foods
Hazards
Toxic substance in condition/in foods
Hazards
Foreign material in condition/in foods
Hazards
5
3. Risk Analysis
Components of risk analysis
Risk communication
(FAO/WHO, 2004)
6
3. Risk Analysis
3.1 Risk assessment
Step 1 hazard identification
Step 2 hazard characterization
Step 3 exposure assessment
Step 4 risk characterization
(CAC, 1999)
7
3. Risk Analysis
3.2 Risk management
The process of weighing policy alternative in
the light of the result of risk assessment, if
required, and selecting and the process of
implementing appropriate control option,
including regulatory measures.
(CAC, 1999)
8
3. Risk Analysis
3.3 Risk communication
The interactive exchange of information and
options concerning risk and risk management among
(CAC, 1999)
9
3. Risk Analysis
3.3 Risk communication
Risk assessors
Consumers and other interested parties
Risk managers
(CAC, 1999)
10
Risk Assessment
1. Hazard identification
The identification of biological, chemical, and
physical agents capable of causing adverse health
effects and which may be present in a particular
food or group of foods.
(CAC, 1999)
11
4. Risk Assessment
Cassin et al., 1998
Objective
Estimating the probability of infection with
E.coli O157H7 in ground beef hamburger
12
Risk Assessment
Cassin et al., 1998
1. Hazard identification
For purpose of microbiological risk assessment
the concerns relate to microorganisms and/or
their toxins.
E.coli O157H7
Hazard
Gram negative, facultative anaerobe, rod shaped
bacteria
13
4. Risk Assessment
Cassin et al., 1998
1. Hazard identification
Cause illness Enterohemorrhagic
E. coli (EHEC) (subgroup of verocytotoxigenic
E.coli (VTECs)
VTECs produce verotoxins
14
4. Risk Assessment
Cassin et al., 1998
1. Hazard identification
Contamination
Slaughtering
Processing
Humans
15
Risk Assessment(conti.)
2 Hazard characterization
The qualitative and/or quantitative evaluation
of the nature of the adverse health effects
associated with the hazard.
(CAC, 1999)
16
4. Risk Assessment
17
Risk Assessment(conti.)
3 Exposure assessment
The qualitative and/or quantitative evaluation
of the likely intake of biological, chemical, and
physical agents via food as well as exposures
from other sources if relevant.
(CAC, 1999)
18
3. Exposure assessment
Flow diagram of mathematical model of exposure
assessment for E.coli O157H7 in hamburgers
Prevalence in faeces
Concentration in faeces
Prevalence in fresh ground beef
Concentration in fresh ground beef
Prevalence in cooked hamburger
Concentration in cooked hamburger
Probability of exposure
Ingested dose
19
Risk Assessment (conti.)
4 Risk characterization
The process of determining the qualitative
and/or quantitative estimation, including
attendant uncertainties, of the probability of
occurrence and severity of known or potential
adverse health effects in a given population
based on hazard identification, hazard
characterization and exposure assessment.
(CAC, 1999)
20
4. Risk Assessment
Cassin et al., 1998
4. Risk characterization
Probability of exposure
Ingested dose
Probability of illness
Probability of mortality
Probability of HUS
21
(No Transcript)
22
4. Risk Assessment
Cassin et al., 1998
4. Risk characterization
The probability of infection with E.coli O157H7
in ground beef hamburger
1.9x10-7 for mortality
23
??????????????????????????????????
24
Codex Alimentarius Food Hygiene Basic Texts

• Joint FAO/WHO Food Standards Programme
• CODEX ALIMENTARIUS COMMISSION
• Codex Alimentarius
• Food Hygiene
• Basic Texts
• Third Edition 2003
• FOOD AND AGRICULTURE ORGANIZATION
• OF THE UNITED NATIONS
• WORLD HEALTH ORGANIZATION

GMP
25
HACCP
12 Steps of Codex
26
?????????
L. monocytogenes ?????????????????????????????????
???
????????????????????????? Listeriosis
??????????????????????????????? 30
Listeria spp. ?????????????????????????????????
??????????????????????????????????????????????????
???? ??????????
27
?????????????????????????????????????? L.
monocytogenes ??????????????????????
????????????????
??????????????????????? (Finished product
testing) ??? ??????????? (Environmental swabs)
?????????????? ?????????????????? ??? ???????
?????????????
??????????????????? ????? L. monocytogenes
???????????? ???????????????
28
??????? ??????? Listeria spp. ???????????????????
?????????????????????????????????????????
????????????? ??????????????? ????????????????????
???????????? ????????????????????????????????
29
Risk Analysis Framework

• Risk Assessment
• Hazard identification
• Hazard characterization
• Exposure assessment
• Risk characterization

• Risk Management
• Asses control options
• Selection and implement appropriate opinions

• Risk Communication
• Interactive exchange of information and opinions

30
?????????????????????
?????????????????????????????????
Pre-cook area
Post-cook area
31
?????????????????????
1 ????????????????????????????????????????????????
??? Listeria spp. ???????????
2. ??????????????????????? Listeria spp.
??????????????????
3 ??????????????????????? Listeria spp.
???????????????????????????
4 ???????????????????????????? Listeria spp.
?????????????????? ???????????????????????????????
????????
32
?????????????????????
5.????????????????????????????????????????????????
?????
6.????????????????????????????????????????????????
??????????????????????? Listeria spp. ???????????
33
?????????????????????
?????????????????????????? Listeria
????????????? ??????????????? Listeria spp. ???
L. monocytogenes ?????????
Tompkin (2000) ????????? ??????????????? Listeria
spp. ??????? L. monocytogenes ?????? 40
???????????????? ?????????????????????????????????
?????????????????
L. monocytogenes ?????????????????????????
34
1 ????????????????????????????????????????????????
??? Listeria spp. ????????????????????????????????
??????????? ?? ???? ??????
????????????
????????????????????????????????
?????????????????????????????????? 20 ???????
??????
35
1 ????????????????????????????????????????????????
??? Listeria spp. ????????????????????????????????
??????????? ?? ???? ??????
????????????????????????? 100 ??? 300 ????
(???????????????????????)
???????????? 6 ????? 1 ??????? (1 ???) ??????????
10 ??????? (10 ???)
????????????????????? Listeria spp.
???????????????????????? ISO 11290-11996
36
2 ??????????????????????? Listeria spp.
?????????????????? ?????? ???? ?? ??????
???????????????????????? ?????????????????????????
????????? Cooker ?????
37
???????? 1. ????????????????????? Listeria spp.
??????????? ??????????????????????
????????????????
38
3 ??????????????????????? Listeria spp.
??????????????????????????? ?????????????????? 3
zones
Zone 2
Zone 1
Zone 3
39
Sanitary Zones
From Dr. R.Bruce Tompkin
40
4.3 ??????????????????????? Listeria spp.
??????????????????????????? ?????????????????? 3
zones
Zone 1
?????????????????????????????????????????
?????????????
??????????????????????
??????????????????????????????????????????????????
41
4.3 ??????????????????????? Listeria spp.
??????????????????????????? ?????????????????? 3
zones
Zone 2
Conveyer
42
3 ??????????????????????? Listeria spp.
??????????????????????????? ?????????????????? 3
zones
Zone 3
Drain
Conveyer
43
3. ??????????????????????? Listeria spp.
??????????????????????????? ?????????????????? 3
zones
1 ??? ??????? ?????? 1 ??????? (6 ??????????)
?????????? 10 ???
????????????????????? Listeria spp. ??? ??? 3M
PetrifilmTM
44
???????? 2. ????????????????????? Listeria spp.
???????????????????? ??? zone ?????
45
(No Transcript)
46
(No Transcript)
47
?????? 1. ????????????????????? Listeria spp.
???????????????????? ??? zone ????????????
48
?????? 2. ????????????????????????????????????????
Listeria spp. ???????????????????
????????????????????? ??? zone ?????
49
?????? 4. ????????????????????????????????????????
Listeria spp. ?????????????????????
????????????????????? ??? zone ?????
50
?????? 6. ????????????????????????????????????????
Listeria spp. ??????????????????????? zone 1 ???
zone 2 ??? 3
51
4 ???????????????????????????? Listeria spp.
?????????????????? ???????????????????????????????
????????
Y ?0?1X1?2X2?kXk?
????? Y ?????????? Listeria spp. ???????????
(?????????)
X ?????????? Listeria spp. ?????????????????????
?? (???????????)
52
4 ???????????????????????????? Listeria spp.
?????????????????? ???????????????????????????????
????????
??????????????????????????????????????????
Listeria spp. ??????????????????? ??????????????
Listeria spp. ????????????????? 1.224 x
Listeria spp. ?? zone 1 ????????????????????? 0
???????????????????? zone ???????????????????????
??????????????? Listeria spp. ????????????????????
? (P 0.05)
53
1. ??????????????????????? 80oC ?? 1 ????
????????????????? Listeria spp. ?????????????????
???? ?? ??????
2. Listeria spp. ?????????????????????????????????
?????????????????????????????????
54
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Dose Response
???????????????? (Hazard Characterization)
Ps
Probability of Listeria spp. on surface (zone
1) at any given time
Proast
Probability of Listeria spp. contamination in
roasted product
0.2214
0.01304 (Ps)
55
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Dose Response
???????????????? (Hazard Characterization)
Proast
Model validation
Predicted
Observed
Ps
56
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Dose Response
???????????????? (Hazard Characterization)
Ps
Probability of Listeria spp. on surface (zone
1) at any given time
Psteam
Probability of Listeria spp. contamination in
steamed product
0.5335
0.00487 (Ps)
57
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Dose Response
???????????????? (Hazard Characterization)
Model validation
Psteam
Predicted
Observed
Ps
58
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Exposure Assessment
x PGrowth
Pinitial x PZ2Z3
Ps
59
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Listeria spp. ????????????????????????
?????????????
Listeria spp. ???????????????????
Growth
Growth
Listeria spp. ???????????????? zone 2 ??? zone 3
????????
60
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
??????? Listeria spp. ???????????????????
??????? Listeria spp. ????????????????????????
x ?????????????? 1 ???????? Listeria spp. ???
zone 2 ??? 3
X ???????? Listeria spp. ??????????????? 1
????????????????????????????
61
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
??????? Listeria spp. ????????????????????????
(Pinitial)
????????????????
1. ??????????????
2. ??????????????????????????????????
3. ?????????????????
62
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Pbefore x Pwater x Pdetergent x Psanitizer
Pinitial
Pbefore
??????? Listeria spp. ??????????????????????
Pwater
???????? Listeria spp. ????????????????????????
????
Pdetergent
???????? Listeria spp. ????????????????????????
??????????
Psanitizer
???????? Listeria spp. ????????????????????????
????
63
1). ??????????????
??????????? 40 50 ??? 60 ????????????
??????? Listeria ?????????????????
???????Listeria ?????????????????
??????????????
64
1). ??????????????
Pwater
water temperature (oC)
65
2). ????????????????????
????????????????????????????
2 1 ??? 0.5
?????????????? 5 10 20 ????
?????????? Listeria ?????????????????
?????????? Listeria ?????????????????
????????????????????
66
4.5.3 ??????????????????? (exposure assessment)
2). ????????????????????
Pdetergent
concentration of detergent ()
contact time (min)
67
3). ?????????????????
?????????????????????????
1.25 0.5 ??? 0.25
?????????????? 5 10 20 ????
??????? Listeria ?????????????????
???????Listeria ?????????????????
?????????????????
68
3). ?????????????????
Psanitizer
concentration of sanitizer ()
contact time (min)
69
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
Psanitizer

????????????????????????? ()
C
T
?????????????? ()
70
4.5 ?????????????????????????????????????
Listeria spp. ??????????????????
???????????????????????? Listeria spp.
?????????????
????????
Pbefore x Pwater x Pdetergent x Psanitizer
Pinitial
Y x 1 x 1 x

Y
?????????? Listeria spp. ??????????????????????
????????????????????????? ()
C
71
4.5 ?????????????????????????????????????
Listeria spp. ??????????????????
???????????????????????? Listeria spp.
?????????????
????????
Pinitial x
Ps
PZ2Z3 x Pgrowth
72
4.5 ?????????????????????????????????????
Listeria spp. ??????????????????
???????????????????????? Listeria spp.
?????????????
??????????? (ti) 0 10 20 ???????
????????????? (??????????????? ti)
??????? Listeria ???????????????
???????Listeria ??????? ti
73
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
PZ2Z3 x Pgrowth
production time (h)
74
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
PZ2Z3 x Pgrowth
2.170
1 0.01352 t
t
Production time (h)
75
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
???????? ??? ??
Pinitial x PZ2Z3 x Pgrowth
Ps
2.170
( 1 0.01352 t )
4.1474 x Y x
Ps

76
5 ????????????????????????????????????? Listeria
spp. ?????????????????? ????????????????????????
Listeria spp. ?????????????
??????????????????? (risk characterization)
Psteam
0.5335
0.00487 (Ps)
2.170
4.1474 Y 0.0560 Y t
Ps

77
????????????????? (roasted product)
?????????????????????????
?????????? Listeria spp. ????????? zone 1
????????
????????
?????????????????????????
78
??????????????????? (risk characterization)
??????????????????? (Steamed product)
?????????????????????????
?????????? Listeria spp. ????????? zone 1 ????????
????????
?????????????????????????
79
6 ????????????????????????????????????????????????
??????????
???????????? ??????????????????????????????????
???

• ?????????????????????????

1.25 ???? 0.5 ???? 0.25

• ????????

0 ???? 10 ???? 20 ???????

• ???????????????????????????????????

20 ???? 10 ???? 5 ????
80
6 ????????????????????????????????????????????????
??????????
????????????????????????????????????????????
???????????? Listeria spp. ?????????????????? ???

• ?????????????????????????

1.25 ???? 0.5 ???? 0.25

• ????????

5 ???????
0 ???? 10 ???? 20 ???????

• ???????????????????????????????????

20 ???? 10 ???? 5 ????
81
6 ????????????????????????????????????????????????
??????????
????????????????????????????????????????
????????????????????? Listeria spp. ???????????
???????
?????????????????
0.0002 ???? 0.02
???????????????????
0.0001 ???? 0.01
82
6 ????????????????????????????????????????????????
??????????
???????????? ??????????????????????????? ???

• ?????????????????????????

1.25 ???? 0.5 ???? 0.25

• ????????

0 ???? 10 ???? 20 ???????

• ???????????????????????????????????

20 ???? 10 ???? 5 ????
83
6 ????????????????????????????????????????????????
??????????
??????????????????????????? ??????????????????????
????????????????????? ????????????????????
Listeria spp. ???????? 106 cfu/ml
??????????????????????????????????????????????????
??

• ??????????????????

40 ???? 50 ???? 60oC

• ????????????????????????????

2 ???? 1 ???? 0.5

• ??????????????????????????????????????

20 ???? 10 ???? 5 ????
84
7 ????????????????????????????????????????????????
??????????????????????? Listeria spp. ???????????
?????????? Listeria spp.???????????
????????????????????????? ??? ???????????????????
aL. innocua and L. welshimeri
85
7 ????????????????????????????????????????????????
??????????????????????? Listeria spp. ???????????
?????????? Listeria spp.????????????????????
????????????????????????? ??? ???????????????????
aL. innocua and L. welshimeri
86
???????????????????????????????????????

• ?????????????????? (Prevent contamination)
• ????????????????????? (Inhibit growth)
• ???????????????? (Remove contamination)

Adapted from Sofos, et al., 1998
87
????????????????????????????????? Listeria
monocytogenes
Doubling Time at 37OC 45 min.
Optimum Temperature37?C Optimum pH 7.0
88
????????????????????????????????? E.coli
a
pH
Oxygen
Temperature
Salt
w
Min.
Max.
Min.
Max.
Max.
Min.
Max.
Requirement
Facultative
O
O
0.95
gt0.99
4.0
9.0
6.5
49.4
C
7.7
C
Anaerobe
O
Doubling Time at 37
C 30 minutes
89
????????????????????????? ????????????????? E.coli
a
Optimum pH
Optimum Temperature
Optimum
w
Min.
Max.
Min.
Max.
0.995
O
O
6.0
7.0
40
C
35
C
90
????????????????????????????????? Salmonella spp.
91
????????????????????????? ?????????????????
Salmonella spp.
a
Optimum pH
Optimum Temperature
Optimum
w
Min.
Max.
Min.
Max.
0.99
O
O
7.0
7.5
43
C
35
C
92
????????????????????????????????? Clostridium
perfringens
a
pH
Oxygen
Temperature
Salt
w
Min.
Max.
Min.
Max.
Max.
Min.
Max.
Requirement
0.97
7
O
O
Anaerobe
0.93
5.0
9.0
52
C
10
C
At 43-47 O C generation time is less than 10 min.
in meat.
93
????????????????????????????????? Bacillus cereus
a
pH
Oxygen
Temperature
Salt
w
Min.
Max.
Min.
Max.
Max.
Min.
Max.
Requirement
-
4.3
9.3
18
O
O
Aerobe
0.92
55
C
4.0
C
94
Danger Zone
95
Cooling Foods
96
???????????????????????????????????????

• ?????????????????? (Prevent contamination)
• ????????????????????? (Inhibit growth)
• ???????????????? (Remove contamination)

Adapted from Sofos, et al., 1998
97
D - Value ???????????????????????????????????
90 (1 log) Z - Value O F/ O C ????????
thermal destruction curve ???? 1 log cycle
(D - Value ???? 10 ????)
Rate of destruction curve.
Thermal death time curve.
Spore of strain F.S.7 heated at 240 OF in canned
pea brine pH 6.2
Jay, J. M., 2000. Modern Food Microbiology 6th
edition. Aspen Publishers.
98
Inactivation of Microorganisms
99
????????????????? Salmonella spp.
????????????????????????? D-Value ???????
a
O
pH
Organism
Medium
D-Value
Temp (
C)
w
S.
Typhimurium
0.99
57.2
1.1 min
6.9
Aq. Sucrose
S.
Typhimurium
0.96
6.9
57.2
14.3 min
Aq. Sucrose
S.
Typhimurium
6.9
0.93
30.5 min
57.2
Aq. Sucrose
6.9
0.90
46.7 min
57.2
Aq. Sucrose
S.
Typhimurium
6.9
0.87
61.5 min
57.2
S.
Typhimurium
Aq. Sucrose
ICMFS (1996), Microorganisms in Foods 5
Characteristics of Microbial Pathogens, Blackie
Academic Professional
100
pH ?????????? D-Value
ICMFS (1996), Microorganisms in Foods 5
Characteristics of Microbial Pathogens, Blackie
Academic Professional
101
????????D-Value???Z-Values ??? Salmonella spp.
D-Value
Z-Value
a
Organism
Medium/Food
w
O
(min)
(
C)
D
61 min
Salmonella
spp.
5.6
-
Ground Meat
(51.6 OC)
D
64 min
6.1
Fat System
-
(51.6 OC)
D
11.32 min
S.
Senftenberg 775
Custard
6.6
-
(60.0 OC)
Chicken a
D
9.61 min
-
6.4
la king
(60.0 OC)
Heart Infusion
D
0.5-0.6 min
6.8
S.
Senftenberg 775
0.998
Broth
(60.0 OC)
Heart Infusion
D
0.5-0.6 min
0.9
13
Broth
(60.0 OC)
ICMFS (1996), Microorganisms in Foods 5
Characteristics of Microbial Pathogens, Blackie
Academic Professional
102
Table 7
Summary of Some Findings on Thermal Destruction
of
L. monocytogenes
Heating
Number of
D Value
z Value
Temp.
Heating Menstrum
O
Cells/ml
(sec.)
(
C)
Strains Tested/State
(
O
C)
5
Scott A, free suspension
10
Sterile skim milk
71.7
1.7
6.5
5
10
Sterile skim milk
71.7
2.0
6.5
5
10
Sterile skim milk
71.7
0.9
6.3
5
Scott A, intracellular
10
Whole raw milk
71.7
1.9
6.0
5
10
Scott A, free suspension
Whole raw milk
71.7
1.6
6.1
6
10
F5069, intracellular
Sterile whole milk
71.7
5.0
8.0
6
F5069, free suspension
Sterile whole milk
71.7
3.1
7.3
10
5
Scott A, free suspension
10
Ice cream mix
79.4
2.6
7.0
8
10
pH 7.2 phos. buffer
70.0
9.0
-
8
10
pH 5.9 meat slurry
70.0
13.8
-
7
10
Liquid whole egg
72.0
36.0
7.1
7
10
Ten strains
Irradiated ground meats
62.0
61.0
4.92
5
Chicken/meat isolate
10
Beef
70.0
7.2
5
10
Minced chicken
70.0
6.7
ICMSF, Vol5
103
???????????????????????????????????????

• Adherence to GMPs (proper facilitiesproper
  equipment design) and SSOPs
• HACCP
• Aggressive environmental monitoring
• Effective corrective actions
• Proper handling practice
• Refrigerate perishable RTE products at lt40 º F
  (lt4.40º C)
• Consume perishable RTE products quickly

104
Logic Behind Environmental Control Program
Finished product testing has significant
limitations.
Probability of Missing Contamination
Contamination in Lot
Number ofSamples Tested
10
2
1
0.5
3 73 94 97 99 10 35 82 90 95 60 lt0.5 3
0 55 74 120 lt0.5 8.5 30 55 180 lt0.5 2.6
16 41 240 lt0.5 0.8 9 30
105
Effectiveness of corrective actions

• Prompt, effective corrective action can limit
  product contamination!

From Dr. R.Bruce Tompkin
106
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107
Four Important Concepts
3. Microbiological Criteria (cfu/g)
Consumption
Illness
Storage
Pasteurization
Raw Ingredients
2. Food Safety Objective (FSO)
4. Performance criteria(Logs Inactivation)
Rather than Process Criteria
1. Acceptable Level of Protection(ALOP)
108
Country level
Food Safety Control
- high level, generic
ALOP
- providing guidance/targets
Risk Analysis
- link between operation and policy
FSO
Food Safety Objective
Operational level
Food Safety Management
Local and specific management at supply chain
level
HACCP
GHPs / GMPs / GAPs
109

110
In conducting the hazard analysis, wherever
possible the following should be included

• the likely occurrence of hazards and severity of
  their adverse health effects
• the qualitative and/or quantitative evaluation of
  the presence of hazards
• survival or multiplication of microorganisms of
  concern
• production or persistence in foods of toxins,
  chemicals or physical agents and,
• conditions leading to the above

111
Health Risk Assessment Model2 Dimensional
Risk
Sa
Mi
Ma
Cr
High
Likelihood of Occurrence
Sa
Mi
Ma
Ma
Med
Sa
Low
Mi
Mi
Mi
Sa
Sa
Sa
Sa
Neg
Low
Med
High
Sa Satisfactory (Negligible) Mi Minor Ma
Major Cr Critical
Severity of Consequences
112
Food-borne Illness

• ?????????????????????
• (Preventable)
• ????????????????????????????????????????

113
Food Safety

• ??????????????
• ???
• ????????????

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???????
114
Main references
CAC. 1999. Principles and guidelines for the
conduct of a microbiological risk assessment
(CAC/GL-30). In Codex Alimentarious Vol. 1B
General requirements (food hygiene). Rome
FAO. Cassin, M. H., Lammerding, A. M., Todd, E.
C. D., Ross, W., and McColl, R. S. 1998.
Quantitative risk assessment for Escherichia coli
O157H7 in ground beef hamburgers. 41
21-44. Lammerding, A. M. and Fazil, A. 2000.
Hazard identification and exposure assessment for
microbial food safety risk assessment. Int. J.
Food Microbiol. 58 147-157. Walls, I. and Scott,
V. N. 1997. Use of predictive microbiology in
microbial food safety risk assessment. Int. J.
Food Microbiol. 36 97-102. Montville, R., Chen,
Y., and Schaffner, D. W. 2002. Risk assessment of
hand washing efficacy using literature and
experimental data. Food Microbiol. 73 305-313.
115
References
Sumalin Lekroengsin, Suwimon Keeratipibul and
Kasame Trakoonlerswilai. 2007. Contamination
Profile of Listeria spp. in Three Types of RTE
Chicken Meat Products, J. of Food Prot. 70(1)in
press Tompkin, et al. 1999. Guidelines to
prevent post-processing contamination from
Listeria monocytogenes. Dairy, Food and Environ.
Sanit. 19551-562. Tompkin. 2002. Control of
Listeria monocytogenes in the food-processing
environment. J. Food Prot. 65709-725. No author
names. 2002. Sampling to assess control of the
environment. Pages 199-224. In Microorganisms in
Foods 7 Microbiological Testing in Food Safety
Management, Kluwer Academic/Plenum Publishers,
New York, NY. Tompkin. 2004. Environmental
sampling A tool to verify the effectiveness of
preventive hygiene measures. Mitt. Lebensm. Hyg.
9545-51. Scott, et al. 2005. Guidelines for
Listeria testing of environmental, raw product
and finished product samples in smoked seafood
processing facilities. Food Prot. Trends 2523-34
116
Thank You
for your attention