Resistance – Thermal and Other Robert L. Buchanan DHHS Food and Drug Administration Center for Food Safety and Applied Nutrition.
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Resistance – Thermal Resistance – Thermal and Other and Other
Robert L. BuchananRobert L. BuchananDHHS Food and Drug AdministrationDHHS Food and Drug Administration
Center for Food Safety and Applied Center for Food Safety and Applied NutritionNutrition
Thermal Resistance of Thermal Resistance of E. E. sakazakii – sakazakii – Laboratory TrialsLaboratory Trials Nazarowec-White and Farber (1997)Nazarowec-White and Farber (1997)
Open stainless steel tubes in constant Open stainless steel tubes in constant temperature water bathtemperature water bath
5 pooled food strains and 5 pooled 5 pooled food strains and 5 pooled clinical strainsclinical strains
Edelson-Mammel and Buchanan Edelson-Mammel and Buchanan (2003)(2003) Submerged coil apparatusSubmerged coil apparatus 12 individual strains – food and clinical12 individual strains – food and clinical
Thermal Resistance Thermal Resistance
D-Value:D-Value: Time at a given temperature Time at a given temperature
needed to reduce a microbial needed to reduce a microbial population by 90%population by 90%
Z-Value:Z-Value: Change in temperature needed to Change in temperature needed to
change D-value by 90%change D-value by 90%
2
3
4
5
6
7
8
9
0 500 1000 1500 2000 2500
Heating Time (sec)
Su
rviv
ors
[Log
(CF
U/m
L)]
Thermal Death Time Curves for 2 Thermal Death Time Curves for 2 Enterobacter sakazakiiEnterobacter sakazakii Strains Strains Heated at 58Heated at 58CC
D = 30.5 secD = 30.5 sec
D = 591.9 secD = 591.9 sec
Distribution of DDistribution of D5858°C°C-values for -values for 12 12 Enterobacter sakazakiiEnterobacter sakazakii strainsstrains
0
1
2
3
4
5
6#
of S
trai
ns
0-100 100-200
200-300
300-400
400-500
500-600
D-value (sec)
Comparison of DComparison of D5858°C°C-Values for -Values for Different EnterobacteriaceaeDifferent Enterobacteriaceae
0
100
200
300
400
500
600
D-v
alue
(se
c)E. sakazakii 607
E. coli O157:H7
E. sakazaki N&F-pooledK. pneuomoniae
Salmonella Hartford
E. coli
E. aerogenes
E. sakazakii 51329
Effect of Heating Temperature Effect of Heating Temperature on D-Value for on D-Value for E. sakazakiiE. sakazakii 607 607
1
10
100
1000
10000
55 60 65 70
Heating Temperature (C)
D-V
alu
e (
sec)
Reported Z-valuesReported Z-values
Nazarowec-White and Farber Nazarowec-White and Farber (1997)(1997) Pooled food isolates: 5.6Pooled food isolates: 5.6°C°C Pooled clinical isolates: 6.0 °CPooled clinical isolates: 6.0 °C All: 5.8 °CAll: 5.8 °C
Edelson-Mammel and Edelson-Mammel and Buchanan (2003)Buchanan (2003) Strain 607: 5.6 °CStrain 607: 5.6 °C
Predicted InactivationPredicted Inactivation
Results of these Results of these heating trials heating trials indicate that indicate that heating heating rehydrated infant rehydrated infant formula at formula at 7070°°C C for even a few for even a few seconds will result seconds will result in a substantial in a substantial inactivation of inactivation of E. E. sakazakiisakazakii
0.001
0.01
0.1
1
10
100
65 70 75 80 85 90 95
Temperature (C)Tim
e to
5D
inact
ivati
on (
sec)
Effect of Temperature of Water Effect of Temperature of Water Used to Rehydrate Infant Used to Rehydrate Infant FormulaFormula Inoculated dried infant formula in
baby bottle Add water pre-heated to different
temperatures Cap and agitate periodically for 10
minutes Analyze rehydrated formula for E.
sakazakii
Temperature Decline During Temperature Decline During Rehydration of Infant Rehydration of Infant FormulaFormula
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
Sample Time (min)
Tem
pera
ture
(C)
Rehydration of Dried Infant Rehydration of Dried Infant FormulaFormula
0
1
2
3
4
5
6Surv
ivors
[L
og(C
FU/m
l)]
23 50 60 70 80 90 100
Water Temperature (C)
Lower Limit of Detection
Impact of Heating on Impact of Heating on Nutrient ContentNutrient Content
Conducted by Atlanta Center Conducted by Atlanta Center for Nutrient Analysis (ACNA)for Nutrient Analysis (ACNA)
Used boiling water as the worst Used boiling water as the worst case and compared against case and compared against controlcontrol
Analyses done in triplicateAnalyses done in triplicate Results expressed in terms of Results expressed in terms of
units/100 calunits/100 cal
Impact of Heating on Impact of Heating on Nutrient ContentNutrient Content
Formula Formula 11
Formula Formula 22
Formula Formula 33
Formula Formula 44
Vitamin Vitamin AA
300/712300/712
686(-3.7)686(-3.7)300/677300/677
678(+0.1)678(+0.1)300/597300/597
613(+2.7)613(+2.7)300/451300/451
459(+1.8)459(+1.8)
Vitamin Vitamin DD
60/7160/71
73(+2.8)73(+2.8)60/5860/58
53(-8.7)53(-8.7)60/5760/57
63(+10.8)63(+10.8)60/5760/57
55(-2.3)55(-2.3)
Vitamin EVitamin E 1.5/2.91.5/2.9
2.9(0.0)2.9(0.0)2.0/5.22.0/5.2
4.4(-14.0)4.4(-14.0)1.4/3.11.4/3.1
3.0(-3.2)3.0(-3.2)2.0/3.72.0/3.7
3.6(-3.5)3.6(-3.5)
Vitamin Vitamin KK
8.0/17.88.0/17.8
17.9(+0.6)17.9(+0.6)8.0/9.48.0/9.4
9.7(+3.2)9.7(+3.2)8.3/11.88.3/11.8
11.9(+0.9)11.9(+0.9)8.2/15.48.2/15.4
14.8(-3.9)14.8(-3.9)
ThiaminThiamin 100/223100/223
218(-2.2)218(-2.2)80/16880/168
170(+1.2)170(+1.2)100/164100/164
178(+8.5)178(+8.5)60/14160/141
141(0.0)141(0.0)
Impact of Heating on Impact of Heating on Nutrient ContentNutrient Content
Formula Formula 11
Formula Formula 22
Formula Formula 33
Formula Formula 44
RiboflaviRiboflavinn
150/266150/266
261(-1.9)261(-1.9)90/15490/154
143(-7.1)143(-7.1)150/247150/247
257(+4.1)257(+4.1)135/337135/337
308(+8.6)308(+8.6)
Vitamin Vitamin BB66
60/8660/86
81(-6.4)81(-6.4)60/11460/114
116(+1.8)116(+1.8)62.5/13662.5/136
139(+2.2)139(+2.2)75/11875/118
120(+1.7)120(+1.7)
Vitamin Vitamin BB1212
0.25/0.900.25/0.90
0.86(-4.4)0.86(-4.4)0.30/0.720.30/0.72
0.72(0.0)0.72(0.0)0.30/0.400.30/0.40
0.41(+3.3)0.41(+3.3)0.22/0.610.22/0.61
0.62(+2.0)0.62(+2.0)
NiacinNiacin 1050/15031050/1503
1521(+1.21521(+1.2))
1000/14181000/1418
1456(+2.71456(+2.7))
750/1242750/1242
1236(-0.5)1236(-0.5)750/1176750/1176
1282(+9.01282(+9.0))
Folic Folic AcidAcid
15.0/36.015.0/36.0
36.1(+1.0)36.1(+1.0)16.0/32.316.0/32.3
33.3(+3.1)33.3(+3.1)7.5/26.97.5/26.9
28.3(+5.2)28.3(+5.2)15.0/43.915.0/43.9
45.2(+3.0)45.2(+3.0)
Impact of Heating on Impact of Heating on Nutrient ContentNutrient Content
Formula Formula 11
Formula Formula 22
Formula Formula 33
Formula Formula 44
PantotheniPantothenic Acidc Acid
450/1010450/1010
1060(+5.01060(+5.0))
500/793500/793
803(+1.3)803(+1.3)450/633450/633
649(+2.5)649(+2.5)450/770450/770
755(+1.9)755(+1.9)
BiotinBiotin 4.4/9.94.4/9.9
10.4(+5.1)10.4(+5.1)3.0/4.63.0/4.6
4.2(-8.0)4.2(-8.0)5.5/6.65.5/6.6
6.7(+2.1)6.7(+2.1)2.2/4.32.2/4.3
4.3(+1.9)4.3(+1.9)
Vitamin Vitamin CC
9.0/16.69.0/16.6
11.5(-11.5(-30.7)30.7)
12.0/26.212.0/26.2
9.0(-65.6)9.0(-65.6)8.3/10.78.3/10.7
10.1(-5.6)10.1(-5.6)8.0/18.38.0/18.3
15.0(-15.0(-18.0)18.0)
Thermal Resistance of Thermal Resistance of E. E. sakazakii sakazakii – Pilot Plant– Pilot Plant
Nazarowec-White et al. (1999)Nazarowec-White et al. (1999) Pooled strains?Pooled strains? HTST pasteurizerHTST pasteurizer
Effectiveness of Effectiveness of PasteurizationPasteurization
3 sec3 sec 10 sec10 sec 16 sec16 sec 30 sec30 sec 60 sec60 sec
5959°C°C 100100 100100
60 60 °C°C 6363 5050
61 61 °C°C 100100 7979 5050 2020
62 62 °C°C 100100 4040 3.23.2 3.23.2
63 63 °C°C 38.838.8 50.150.1 2020 0.630.63 0.400.40
64 64 °C°C 39.839.8 1616 5.05.0 0.0130.013 0.0400.040
65 65 °C°C 31.631.6 2.02.0 0.200.20 0.00040.0004
66 66 °C°C 6.316.31 0.200.20 0.0790.079
67 67 °C°C 0.3980.398
68 68 °C°C 0.0630.063
Resistance to Other Resistance to Other TreatmentsTreatments
Great deal of information available Great deal of information available about about EnterobacteriaceaeEnterobacteriaceae in general in general
Resistances If Like Other Resistances If Like Other EnterobacteriaceaeEnterobacteriaceae Not heat resistantNot heat resistant Moderate acid resistance if adaptedModerate acid resistance if adapted Moderate alkali resistance if adaptedModerate alkali resistance if adapted Low to moderate chlorine resistanceLow to moderate chlorine resistance Low to moderate irradiation Low to moderate irradiation
resistanceresistance Will remain viable in refrigerated and Will remain viable in refrigerated and
frozen products for extended periods, frozen products for extended periods, particularly if neutral pHparticularly if neutral pH
Moderate to good resistance to dryingModerate to good resistance to drying
Resistance to Other Resistance to Other TreatmentsTreatments
Little published Little published information available information available specifically about specifically about E. E. sakazakiisakazakii
Even less available on Even less available on distribution of resistancesdistribution of resistances
Other ResistancesOther Resistances
Isolation from dried foods indicates Isolation from dried foods indicates resistance to dryingresistance to drying
Isolation from seeds treated with Isolation from seeds treated with hypochlorite suggest that at least hypochlorite suggest that at least some strains may be relatively some strains may be relatively resistant to chlorine (Okuda et al., resistant to chlorine (Okuda et al., 1994)1994)
Relatively sensitive to the growth Relatively sensitive to the growth inhibiting effects of chitosans (No et inhibiting effects of chitosans (No et al., 2002)al., 2002)
Resistance to DehydrationResistance to Dehydration
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0 2 4 6 8 10
Storage Time (mon)
Surv
ivin
g P
opula
tion
[Log(C
FU/m
L)]
SummarySummary
Not a particularly thermally Not a particularly thermally resistant microorganismresistant microorganism
Substantial diversity in thermal Substantial diversity in thermal resistance among strainsresistance among strains
Good agreement among studiesGood agreement among studies Inactivation at temperatures above Inactivation at temperatures above
7070°C, even for a few seconds °C, even for a few seconds Specific information on its Specific information on its
resistance to other treatments is resistance to other treatments is generally lackinggenerally lacking
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