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Chapter IV: Growth/Survival Tables

Analysis and Evaluation of Preventive Control Measures for the Control and Reduction/Elimination of Microbial Hazards on Fresh and Fresh-Cut Produce

Table of Contents

Chapter IV

Incidence Tables   |   Outbreaks Tables   |   Growth/Survival Tables

Outbreaks Associated with Fresh Produce: Incidence, Growth, and Survival of Pathogens in Fresh and Fresh-Cut Produce


Table G/S-1: Survival and Growth of Pathogenic Bacteria on Raw Melons

PathogenMelon TypepHMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Campylobacter jejuniWatermelon, cubes3.0Spot inoculation, cells suspended in saline. 0.02 ml inoculated per cube.24 cm2 cubes with 0.05 ml of lemon juice added per cube. Stored in covered sterile stainless-steel trays.25-292.96 h2CFU/cube
pH 4.8 after 6 h.Castillo and Escartin 1994
C. jejuniWatermelon, cubes5.5Spot inoculation, cells suspended in saline. 0.02 ml inoculated per cube.24 cm2 cubes without lemon juice. Stored in covered sterile stainless-steel trays.25-292.76 h2.1CFU/cube
pH 5.5 after 6 h.Castillo and Escartin 1994
C. jejuniWatermelon, cubes5.5Spot inoculation, cells suspended in saline. 0.02 ml inoculated per cube.24 cm2 cubes without lemon juice. Stored in sterile stainless-steel trays with cover.25-292.46 h1.6CFU/cube
pH 5.5 after 6 h.Castillo and Escartin 1994
Escherichia coli O157:H7
(4 strains)
Cantaloupe, rind surfaceNRaSpot inoculation, cells diluted in 0.1% peptone.Melons were held in covered plastic boxes with 93 + 5% relative humidity.25
5
~5.2
~5.2
21 d
8 d
~7.1
<1.0
CFU/cm2
CFU/cm2
-Del Rosario and Beuchat 1995
E. coli O157:H7 (4 strains)Cantaloupe, cubes7.01Cell suspension diluted in 0.1% peptone and added to sample.Cubes placed in sealed stomacher bags and incubated.25
5
3.0
~3.1
34 h
34 h
~7.0
~3.1
CFU/g
CFU/g
-Del Rosario and Beuchat 1995
E. coli O157:H7 (4 strains)Watermelon, cubes5.56Cell suspension diluted in 0.1% peptone and added to sample.Cubes placed in sealed stomacher bags and incubated.25
5
3.0
3.0
34 h
34 h
~8.7
~3.0
CFU/g
CFU/g
-Del Rosario and Beuchat 1995
E. coli O157:H7 (4 strains)Watermelon, rind surface-Spot inoculation, cells diluted in 0.1% peptone.Melons were held in covered plastic boxes with 93 + 5% relative humidity.25
5
~5.2
~5.2
14 d
14 d
~6.4
<1.0
CFU/cm2
CFU/cm2
-Del Rosario and Beuchat 1995
Salmonella (5 serotypes)Cantaloupe, cubes6.67Cell suspension diluted in Butterfield's phosphate buffer, added to sample.Cubes placed in open stomacher bags and incubated aerobically.23
5
2.0
2.0
24 h
24 h
~7.2
~1.6
CFU/g
CFU/g
-Golden and others 1993
Salmonella (5 serotypes)Honeydew, cubes5.95Cell suspension diluted in Butterfield's phosphate buffer, added to sample.Cubes placed in open stomacher bags and incubated aerobically.23
5
2.0
2.0
24 h
24 h
~8.0
~1.8
CFU/g
CFU/g
-Golden and others 1993
Salmonella (5 serotypes)Watermelon, cubes5.90Cell suspension diluted in Butterfield's phosphate buffer, added to sample.Cubes placed in open stomacher bags and incubated aerobically.23
5
2.0
2.0
24 h
24 h
8.6
~1.9
CFU/g
CFU/g
-Golden and others 1993
Shigella flexneriWatermelon, cubesNRSpot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated and stored in sterile covered glass trays.22-262.86 h4.5CFU/cm2-Fernandez Escartin and others 1989
S. sonnei
Watermelon, wholeNR30 ml of inoculum was injected into the whole watermelon through the stem scar.30 ml of inoculum was injected and incubated.30
22
2.0
2.0
2 d
4 d
~9.0

~9.0
CFU/g CFU/gInoculated with > 102 CFU/g. Melon rotten within 1-2 days at 30°C and 2-3 days at 22°C.Fredlund and others 1987
a Not reported


 

Table G/S-2: Survival and Growth of Pathogenic Bacteria on Raw Fruit Other than Melons

PathogenFruit TypepHMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Campylobacter jejuniPapaya, cubes3.0Spot inoculation, cells suspended in saline. 0.02 ml inoculated per cube.24 cm2 cubes with 0.05 ml of lemon juice added. Stored in sterile stainless-steel trays with cover.25-293.36 h<1.0CFU/cube
pH 3.6 after 6 h.Castillo and Escartin 1994
C. jejuniPapaya, cubes5.0Spot inoculation, cells suspended in saline. 0.02 ml inoculated per cube.24 cm2 cubes without lemon juice. Stored in sterile stainless-steel trays with cover.25-292.86 h1.7CFU/cubepH 5.0 after 6 h.Castillo and Escartin 1994
Escherichia coli O157:H7Apple (Golden delicious, fresh cut tissue)NRaSpot inoculation, 25 µl inoculated per wound. Inoculum suspended in 0.85% saline.Apples were wounded (one wound per fruit) aseptically by removing a cyclinder of tissue 3 mm in diameter by 3 mm deep. Stored in plastic boxes on fruit pack trays.242.0
4.0
6.0
48 h
48 h
48 h
~5.5
~6.0
~6.5
CFU per wound-Janisiewicz and others 1999
E. coli O157:H7 (2 strains)Apples (Red delicious, ground)4.10Cell suspension in tryptone soy broth, inoculated into sample.Ground apples were stored in a plastic stomacher bag.4
10
25
~7.518 d
12 d
5 d
~6.8
~5.8
~8.5
CFU/ml CFU/ml CFU/mlFinal pH 5.11. At 25oC no growth within 24 h.Fisher and Golden 1998
E. coli O157:H7 (2 strains)Apple (Golden delicious, ground)3.84Cell suspension in tryptone soy broth, inoculated into sample.Ground apples were stored in a plastic stomacher bag.4
10
25
~7.518 d
12 d
5 d
~7.2
~6.8
~8.2
CFU/ml CFU/ml CFU/mlFinal pH 4.95. At 25oC no growth within 24 h.Fisher and Golden 1998
E. coli O157:H7 (2 strains)Apples (Rome, ground)3.70Cell suspension in tryptone soy broth, inoculated into sample.Ground apples were stored in a plastic stomacher bag.4
10
25
~7.518 d
12 d
5 d
~6.8
~7.0
~7.5
CFU/ml CFU/ml CFU/mlFinal pH 3.91. At 25oC no growth within 24 h. Slight growth at 48 h followed by decline.Fisher and Golden 1998
E. coli O157:H7
(2 strains)
Apples (Winesap, ground)3.47Cell suspension in tryptone soy broth, inoculated into sample.Ground apples were stored in a plastic stomacher bag.4
10
25
~7.518 d
12 d
5 d
~7.0
~7.0
~7.0
CFU/ml CFU/ml CFU/mlFinal pH 4.03.Fisher and Golden 1998
E. coli O157:H7Apple
(5 cultivars, whole)
3.5-4.9Infected with 0.1 ml of saline suspension of cells, then wholes were sealed with tape.Stored in plastic tub at room temperature.20-255.0-5.22 d4.8 - 8.3CFU/appleSurvival and growth depended on cultivars and days post harvest.  dropped fruit did not differ from tree-picked fruit in promoting growth.Dingman 2000
E. coli O157:H7 (2 strains)Orange (Hamlin, peeled)6.0-6.5Spot inoculation, 20 µl inoculated and spread over 1/8 of total suface area. Inoculum suspended in Butterfield's phosphate buffer.Inoculated fruit were individually packed in perforated plastic containers.4
8
24
3.514 d
14 d
1 d
~3.2
~2.5
~7.5
CFU/g CFU/g CFU/gpH of surface 6.0-6.5. Juice pH 3.8.Pao and others 1998
Listeria monocytogenes (2 strains)Orange, (Hamlin, peeled)6.0-6.5Spot inoculation, 20 µl inoculated and spread over 1/8 of total suface area. Inoculum suspended in Butterfield's phosphate buffer.Inoculated fruit were individually packed in perforated plastic containers.4
8
24
3.914 d
14 d
1 d
~4.0
~3.3
~5.5
CFU/g CFU/g CFU/g-Pao and others 1998
Staphylococcus aureus
(2 strains)
Orange, (Hamlin, peeled)6.0-6.5Spot inoculation, 20 µl inoculated and spread over 1/8 of total suface area. Inoculum suspended in Butterfield's phosphate buffer.Inoculated fruit were individually packed in perforated plastic containers.4
8
24
~2.814 d
14 d
1 d
~2.0
~2.0
~3.5
CFU/g CFU/g CFU/g-Pao and others 1998
Salmonella ChesterApple (Golden delicious, disks)4.1Dip inoculation, 30 s. Cells suspended in phosphate-buffered saline (pH 7.2).NR8~ 5.566 h~ 5.3CFU/diskAcidity did not markedly affect viabilityLiao and Sapers 2000
S. ChesterApple (Golden delicious, disks)4.1Dip inoculation, 30 s. Cells suspended in phosphate-buffered saline (pH 7.2).NR20~ 5.566 h~ 10.4CFU/diskIncreased to ca. 10.2 log10 CFU/disk within 18 hLiao and Sapers 2000
S. TyphiPapaya, cubes5.69Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated, and stored in covered glass trays.25-272.96 h4.3CFU/cube-Fernandez Escartin and others 1989
S. TyphiPapaya, cubes3.59Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, 0.05 ml lemon juice added, inoculated, and stored in covered glass trays.25-273.06 h3.8CFU/cube-Fernandez Escartin and others 1989
Salmonella (2 serotypes)Orange, (Hamlin, peeled)6.0-6.5Spot inoculation, 20 µl inoculated and spread over 1/8 of total suface area. Inoculum suspended in Butterfield's phosphate buffer.Inoculated fruit were individually packed in perforated plastic containers.4
8
24
4.414 d
14 d
1 d
~3.5
~2.5
~7.6
CFU/g CFU/g CFU/g-Pao and others 1998
Shigella (3 species)Papaya, cubes5.69Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated and stored in covered glass trays.25-272.0-2.46 h3.8-4.2CFU/cubeS. sonnei,
S. flexneri,
S. dysenteriae
Fernandez Escartin and others 1989
a Not reported


 

Table G/S-3: Survival and Growth of Pathogenic Bacteria on Raw Tomatoes

PathogenProduce TypepHMethod of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Listeria monocytogenes (2 strains)Tomato (chopped)4.1Cells suspended in 0.1 M phosphate buffer, 10 ml mixed in 1000 g of tomatoes.Stored in sealed bags with 3% O2 and 97% N2 or ambient air. Tomatoes either unwashed or washed in 210-280 ppm chlorine prior to chopping.104.5-4.810 d~3.5-4.2CFU/gSubjectively judged to be inedible after 10 days due to deterioration.Beuchat and Brackett 1991
L. monocytogenes (2 strains)Tomato (chopped)4.1Cell suspension in 0.1 M phosphate buffer, 10 ml mixed in 1000 g of tomatoes.Stored in sealed bags with 3% O2 and 97% N2 or ambient air. Tomatoes either unwashed or washed in 210-280 ppm chlorine prior to chopping.2158 d1.0-3.5CFU/gSurvival slightly better in chlorine treated samples.Beuchat and Brackett 1991
L. monocytogenes (2 strains)Tomato (whole, cherry)NraDip inoculation, inoculum suspended in 0.1 M phosphate buffer.Stored in sealed bags with 3% O2 and 97% N2 or ambient air. Tomatoes either not washed or washed in 210-280 ppm chlorine.103.5-3.720 d3.5-5.0CFU/gSignificant growth observed only for Scott A inoculated onto chlorine treated tomatoes stored in air. Little difference between strains, tomato treatments, or storage conditions.Beuchat and Brackett 1991
L. monocytogenes (2 strains)Tomato (whole, cherry)NRDip inoculation, inoculum suspended in 0.1 M phosphate buffer.Stored in sealed bags with 3% O2 and 97% N2 or ambient air. Tomatoes either not washed or washed in 210-280 ppm chlorine.213.4-3.62-8 d4.8-5.5CFU/gSignificant growth observed only for Scott A inoculated onto chlorine treated tomatoes stored in air. Little difference between strains, tomato treatments, or storage conditions.Beuchat and Brackett 1991
Salmonella BaildonTomato (diced)4.50-4.52Cells suspended in deionized water; 30 ml mixed with 2270 g of tomatoes.Tomatoes (450 g) were sealed in plastic bags. Stored for up to 12 d.40.412 d<1.0CFU/gNot detected in 6 enriched 25-g samples analyzed each day (0, 2, 5, 8, 12 d).Weissinger and others 2000
S. BaildonTomato (diced)4.50-4.52Cells suspended in deionized water; 30 ml mixed with 2270 g of tomatoes.Tomatoes (450 g) were sealed in plastic bags. Stored for up to 12 d.43.412 d1.8CFU/gCounts were reduced by 0.40, 0.67. and 0.75 log10 CFU/g after 2, 5, and 8 d, respectively.Weissinger and others 2000
S. BaildonTomato (diced)4.39-4.41Cell suspended in deionized water; 20 ml mixed with 600 g of tomatoes.Tomatoes (100 g) were sealed in plastic bags. Stored for up to 72 h.210.7972 h8.1CFU/gCounts were 5.32 and 7.60 log10 CFU/g after 24 and 48 h, respectively.Weissinger and others 2000
S. BaildonTomato (diced)4.39-4.41Cells suspended in deionized water; 20 ml mixed with 600 g of tomatoes.Tomatoes (100 g) were sealed in plastic bags. Stored for up to 72 h.300.7972 h7.94CFU/gCounts were 7.30 and 7.90 log10 CFU/g after 24 and 48 h, respectively.Weissinger and others 2000
S. MontevideoTomato (cut slices)4.31-4.52Spot inoculation, inoculum suspended in distilled water. 25 µl inoculated onto each slice.Tomato sliced into quarters.253.4
4.4
7.4
12 h
12 h
12 h
~7.5
~8.0
~9.5
CFU/slice-Wei and others 1995
S. MontevideoTomato (mature green, wounded)4.33-4.52Spot inoculation, inoculum suspended in distilled water. 25 µl inoculated onto each wounded area.Tomatoes were punctured to a depth of 1-mm and 0.6-cm in diameter in eight separate areas.253.0
4.0
7.0
24 h~4.8
~5.5
~7.0
CFU per wounded area-Wei and others 1995
S. MontevideoTomato (ripe, chopped)4.1Cell suspension in 0.05 M potassium phosphate buffer. 1ml inoculated into 50 g sample.1-cm cubes. Stored in stomacher bags.5
20
30
4.496 h
22 h
22 h
~4.2
~6.0
~7.0
CFU/g CFU/g
CFU/g
Tomatoes inedible after 22 h at 20 or 30°C and after 96 h at 5°C.Zhuang and others 1995
S. MontevideoTomato (stem scar)NRSpot inoculation, inoculum suspended in distilled water. 25 µl inoculated onto stem scar.-20
25
8.0
8.0
7 d
7 d
6.5
5.8
CFU/stem scar-Wei and others 1995
S. MontevideoTomato (stem scar)NRSpot inoculation, inoculum suspended in TSB. 25 µl inoculated onto stem scar.-20
25
7.2
7.2
7 d
7 d
4.6
6.3
CFU/stem scar-Wei and others 1995
S. MontevideoTomato (whole, mature green)NRDip inoculation, inoculum suspended in 0.1 M phosphate buffer.Stored individually in open plastic bags with relative humidity between 45-60%.10
20
30
~1.41-18 d
7 d
2 d
~ 2.2
~4.0
~5.0
CFU/cm2Populations declined at 20 and 30°C after day 7.Zhuang and others 1995
S. MontevideoTomato, skinNRSpot inoculation, cells suspended in distilled water. Sterile filter discs submerged in inoculum and placed on tomatoes.Filter discs were dried at room temperature for 2 h and removed from tomatoes. Tomatoes were stored at 83% (20°C) or 72% (25°C) relative humidity.20
25
5.8
5.8
5 d
3 d
<1
<1
CFU/area inoculated-Wei and others 1995
S. MontevideoTomato, skinNRSpot inoculation, cells suspended in TSB. Sterile filter discs submerged in inoculum and placed on tomatoes.Filter discs were dried at room temperature for 2 h and removed from tomatoes. Tomatoes were stored at 83% (20°C) or 72% (25°C) relative humidity.20
25
5.5
5.5
7 d
7 d
2.6
4.1
CFU/area inoculated-Wei and others 1995
Salmonella
(3 serotypes)
Tomato (cut, small pieces)4.0-4.40Cell suspension in saline, 0.1 ml inoculated into 20 g of sample.Inoculated samples sealed in polyethylene plastic bags.22
30
1.124 h6.3-6.9
7.2-8.4
CFU/g
CFU/g
Final pH 3.90-4.36. S. Enteriditis,
S. Infantis, and
S. Typhimurium.
Asplund and Nurmi 1991
aNot reported


 

Table G/S-4: Survival and Growth of Pathogenic Bacteria on Raw Vegetables Other than Tomatoes, Sprouts, Lettuce, and Salads

PathogenProduce TypepHMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Aeromonas hydrophila
(2 strains)
AsparagusNRaDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in 6% CO2, 79% N2, and 15% O2 in glass jars.15
4
4.5
4.5
4 d
14 d
~8.0
~ 7.5
CFU/g CFU/gAsparagus first became unacceptable for consumption on day 6 (15°C) or day 21 (4°C).Berrang and others 1989a
A. hydrophila
(2 strains)
AsparagusNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
4.5
4.5
4 d
21 d
~8.0
~ 7.5
CFU/g CFU/gAsparagus first became unacceptable for consumption on day 4 (15°C) or day 15 (4°C).Berrang and others 1989a
A. hydrophila
(2 strains)
BroccoliNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in 10% CO2, 79% N2, and 11% O2 in glass jars.15
4
5.1
4.0
4 d
14 d
~8.2
~6.0
CFU/g CFU/gBroccoli first became unacceptable for consumption on day 10 (15°C) or day 21 (4°C).Berrang and others 1989a
A. hydrophila
(2 strains)
BroccoliNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
5.1
4.0
4 d
14 d
~8.2
~6.0
CFU/g CFU/gBroccoli first became unacceptable for consumption on day 6 (15°C) or day 21 (4°C).Berrang and others 1989a
A. hydrophila
(2 strains)
CauliflowerNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
4.0
3.5
4 d
14 d
~8.5
~ 5.9
CFU/g CFU/gCauliflower first became unacceptable for consumption on day 6 (15°C) or day 21 (4°C).Berrang and others 1989a
A. hydrophila
(2 strains)
CauliflowerNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in 3% CO2, 79% N2, and 18% O2 in glass jars.15
4
4.0
3.5
4 d
14 d
~8.5
~6.0
CFU/g CFU/gCauliflower first became unacceptable for consumption on day 8 (15°C) or day 21 (4°C).Berrang and others 1989a
A. hydrophila (1 strain)Endive (chicory)NRCell suspension added to samples.Stored in moderate vacuum packaging containers under moderate vacuum.6.53.23-7 d~7.0CFU/g-Aytac and Gorris1994
A. hydrophila (1 strain)Endive (chicory)NRCell suspension added to samples.Stored in moderate vacuum packaging container in ambient air.6.53.23 d6.5CFU/gPopulations declined to Log 1.0 CFU/g by day 7.Aytac and Gorris1994
A. hydrophilaVegetable salads (mixed vegetable)6.0Cell suspension, injected through a silicone septum. Cells suspended in brain heart infusion broth.Samples sealed and stored in polypropylene plastic film.4
15
3.0
3.0
9 d
24 h
~3.5
~7.9
CFU/gPopulation at 15°C steadily declined from 24 h to 6 d.Garcia-Gimeno and others 1996
Clostridium botulinum (10 strains)Broccoli6.9Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples loosely packaged and stored in sealed polyethylene bags.212.03 d
 
NRspores/g6/6 samples toxic. Spoilage observed.Larson and others 1997
C. botulinum (10 strains)Broccoli6.9Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples loosely packaged and stored in sealed polyethylene bags.122.09 dNRspores/g3/6 samples toxic. Gross spoilage observed.Larson and others 1997
C. botulinum (10 strains)Broccoli6.9Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples loosely packaged and stored in sealed polyethylene bags.42.030 dNRspores/g0/6 samples toxic. Gross spoilage observed.Larson and others 1997
C. botulinum nonproteolytic
(8 strains)
Butternut squashNRSpore suspension (2.5 ml) added to 500 g sample.1-inch cubes, inoculated and sealed in a polystyrene tray.10
5
3.0
3.0
7 d
21 d
NRspores/gToxin detected at 7 d (10°C) or 21 d (5°C). No change in appearance. Final pH 6.4 (5°C), 6.7 (10°C).Austin and others 1998
C. botulinum proteolytic
(10 strains)
Butternut squashNRSpore suspension (2.5 ml) added to 500 g sample.1-inch cubes, inoculated and sealed in a polystyrene tray.15
25
2.0
2.0
14 d
3 d
NRspores/gToxin detected at 14 d (15°C) or 3 d (25°C). 15°C samples dry and moldy. Swelling of packaged observed in 25°C samples. Final pH 6.5 (15°C), 6.2 (25°C).Austin and others 1998
C. botulinum
(12 strains)
Cabbage (shredded)NRSpore suspension (1 ml), heat shocked, sprayed onto sample. Spores were suspended in gel-phosphate buffer.Samples were sealed in 3-qt pouches and stored vented or not vented. Vented bags were placed with space between samples so that air could circulate.4.4
12.7
21
2.1
2.1
2.1
28 d
28 d
28 d
2.2
2.0
NDb
MPN spores/gNo toxin detected in samples stored at 4.4°C or 12.7°C. Toxin detected in non-vented samples stored at 21°C after 7 d. Samples were judge to be inedible prior to toxin detection.Petran and others 1995
C. botulinum
(10 strains, 5 type A and 5 type B)
Cabbage (shredded)6.2Spore suspended in water, 1 ml heat shocked suspension added to sample.Stored in ethylene vinyl alcohol bags. Sealed in MAP of 70% CO2 and 30% N2.22-250.8-1.86 dNRspores/gNo toxin detected.Solomon and others 1990
C. botulinum
(10 strains, 5 type A and 5 type B)
Cabbage (shredded)6.2Spore suspended in water, 1 ml heat shocked suspension added to sample.Stored in ethylene vinyl alcohol bags. Sealed in MAP of 70% CO2 and 30% N2.22-252-2.34 dNRspores/g5/6 bags toxic. Cabbage acceptable. Only type A grew and produced toxin.Solomon and others 1990
C. botulinum
(10 strains, 5 type A and 5 type B)
Cabbage (shredded)6.2Spore suspended in water, 1 ml heat shocked suspension added to sample.Stored in ethylene vinyl alcohol bags. Sealed in MAP of 70% CO2 and 30% N2.22-252.94 dNRspores/g2/2 bags toxic. Cabbage acceptable. Only type A grew and produced toxin.Solomon and others 1990
C. botulinum (5 strains, type A)Cabbage (shredded)6.2Spore suspended in water, 1 ml heat shocked suspension added to sample.Stored in ethylene vinyl alcohol bags. Sealed in MAP of 70% CO2 and 30% N2.22-251.6-2.16 dNRspores/gNo toxin detected.Solomon and others 1990
C. botulinum (5 strains, type A)Cabbage (shredded)6.2Spore suspended in water, 1 ml heat shocked suspension added to sample.Stored in ethylene vinyl alcohol bags. Sealed in MAP of 70% CO2 and 30% N2.22-252.5-3.04 d
5 d
6 d
NRspores/g5/10 bags toxic at 4 d, 8/10 bags toxic at 5 d, and 9/10 bags toxic at 6 d. Cabbage acceptable.Solomon and others 1990
C. botulinum (10 strains)Cabbage (shredded)6.4Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples stored in polyethylene bags and vacuum sealed.4
12
21
2.037
8
4
NRspores/g0/6 samples were toxic at end of storage for all three temperatures. Gross spoilage was observed.Larson and others 1997
C. botulinum (10 strains)Carrot (sliced)6.3Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples stored in polyethylene bags and vacuum sealed.4
12
21
2.078 d
14 d
4 d
NRspores/g0/6 samples were toxic at end of storage for all three temperatures. Gross spoilage was observed.Larson and others 1997
C. botulinum nonproteolytic
(8 strains)
ColeslawNRSpore suspension (1 ml) injected through gas-tight septum.Samples in original package.5
10
3.021 dNRspores/gNo toxin detected after 21 d. No change in appearance.Austin and others 1998
C. botulinum proteolytic
(10 strains)
ColeslawNRSpore suspension (1 ml) injected through gas-tight septum.Samples in original package.15
25
2.021 dNRspores/gNo toxin detected after 21 d. No change in appearance.Austin and others 1998
C. botulinum
(10 strains)
Green beans6.3Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples loosely packaged and stored in sealed polyethylene bags.4
12
21
2.035
9
7
NRspores/g0/6 samples toxic at end of storage for all three temperatures. Gross spoilage observed.Larson and others 1997
C. botulinum proteolytic
(10 strains)
Mushroom (enoki)NRSpores suspended in trypticase peptone glucose yeast extract, 0.1ml inoculated per package.Stored under anaerobic conditions in sealed bags.6
15
15
27
3.021 d
7 d
14 d
2 d
No toxin
No toxin
Toxin
Toxin
spores/ packageSpoilage evident when toxin detected.Malizio and Johnson 1991
C. botulinum proteolytic
(10 strains)
Mushroom (enoki)NRSpores suspended in trypticase peptone glucose yeast extract, 0.1ml inoculated per package.Stored under anaerobic conditions in sealed bags.15
27
27
2.014 d
2 d
4 d
Toxin
No toxin
Toxin
spores/ packageSpoilage evident when toxin detected.Malizio and Johnson 1991
C. botulinum proteolytic
(10 strains)
Mushroom (enoki)NRSpores suspended in trypticase peptone glucose yeast extract, 0.1ml inoculated per package.Stored under anaerobic conditions in sealed bags.15
21
27
27
1.014 d 21 d
2 d
4 d
No toxin
Toxin
No toxin
Toxin
spores/ packageSpoilage evident when toxin detected.Malizio and Johnson 1991
C. botulinum proteolytic
(10 strains)
OnionNRSpore suspension (2.5 ml) added to 500 g sample.5-mm slices, inoculated and sealed in polystyrene trays.253.06 d-spores/gToxin detected at 6 d. Swelling of package observed but no change in appearance of onions.Austin and others 1998
C. botulinum nonproteolytic
(8 strains)
RutabagaNRSpore suspension (2.5 ml) added to 500 g sample.1-inch cubes, inoculated and sealed in polystyrene tray.5
10
3.0
3.0
21 dNRspores/gNo toxin detected after 21 d. No change in appearance.Austin and others 1998
C. botulinum proteolytic
(10 strains)
RutabagaNRSpore suspension (2.5 ml) added to 500 g sample.1-inch cubes, inoculated and sealed in polystyrene tray.15
25
2.0
2.0
21 dNRspores/gNo toxin detected after 21 d (15°C). No change in appearance. At 25°C toxin detected at 7 d. decay evident. Final pH 5.9.Austin and others 1998
C. botulinum
nonproteolytic
(8 strains)
Stir fry vegetablesNRSpore suspension (1 ml) injected into sealed bags through gas-tight septum.Stored in plastic film.5
10
3.0
3.0
21 d3.0
3.3
CFU/gNo toxin detected after 21 d. No change in appearance.Austin and others 1998
C. botulinum proteolytic
(10 strains)
Stir fry vegetablesNRSpore suspension (1 ml) injected into sealed bags through gas-tight septum.Stored in plastic film.152.021 d2.8CFU/gNo toxin detected at 21 d. No change in appearance.Austin and others 1998
C. botulinum proteolytic
(10 strains)
Stir fry vegetablesNRSpore suspension (1 ml) injected into sealed bags through gas-tight septum.Stored in plastic film.252.011 d>4.5CFU/gToxin detected at 11 d. Soft appearance. Final pH 4.2.Austin and others 1998
Escherichia coli O157:H7 (5 strains)Carrot (shredded)7.1Dip inoculation, 1 min. Cells suspended in deionized water.Stored in polyolefin L-bags consisting 3% O2 and 97% N2.5
12
21
2.53 d
3 d
7 d
<1
<1
4.2
CFU/gSamples held at 5°C and 12°C were positive upon enrichment through day 14.Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Carrot (shredded)7.1Dip inoculation, 1 min. Cells suspended in deionized water.Stored in air in polyolefin L-bags.5
12
21
5.33 d
14 d
7 d
4.6
6.3
6.0
CFU/gSamples held at 5°C were positive upon enrichment through day 14.Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Carrot (shredded)7.1Dip inoculation, 1 min. Cells suspended in deionized water.Stored in air in polyolefin L-bags.5
12
21
2.53 d
3 d
7 d
<1
<1
3.8
CFU/gSamples held at 5°C and 12°C were positive upon enrichment through day 14.Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Carrot (shredded)7.1Dip inoculation, 1 min. Cells suspended in deionized water.Stored in polyolefin L-bags consisting 3% O2 and 97% N2.5
12
21
5.33 d
14 d
7 d
4.1
6.6
6.5
CFU/gSamples held at 5°C were positive upon enrichment through day 14.Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Cucumber (sliced)7.3Dip inoculation, 1 min. Cells suspended in deionized water.5-mm discs, stored in 3% O2 and 97% N2 in polyolefin L-bags.5
12
21
5.110 d
10 d
7 d
2.3
5.4
4.6
CFU/g-Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Cucumber (sliced)7.3Dip inoculation, 1 min. Cells suspended in deionized water.5-mm discs, stored in 3% O2 and 97% N2 in polyolefin L-bags.5
12
21
2.33 d
3 d
7 d
<1
<1
2.6
CFU/gSamples stored at 5 and 12°C were positive upon enrichment through day 3 and day 7, respectively.Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Cucumber (sliced)7.3Dip inoculation, 1 min. Cells suspended in deionized water.5-mm discs, stored in air in polyolefin L-bags.5
12
21
5.110 d
10 d
7 d
3.4
5.7
2.6
CFU/g-Abdul-Raouf and others 1993
E. coli O157:H7 (5 strains)Cucumber (sliced)7.3Dip inoculation, 1 min. Cells suspended in deionized water.5-mm discs, stored in air in polyolefin L-bags.5
12
21
2.33 d
3 d
7 d
<1
<1
3.1
CFU/gSamples stored at 5 and 12°C were positive upon enrichment through day 3 and day 10, respectively.Abdul-Raouf and others 1993
Listeria monocytogenes
(1 strain)
AsparagusNRCells injected into samples.Stored in hemetically sealed bags.2
4
8
12
20
5.0
5.0
5.0
5.0
5.0
6-24 d
6-24 d
3-24 d
3-15 d
3-6 d
4.5
5.0
7.0
9.0
9.0
CFU/g
CFU/g
CFU/g
CFU/g
CFU/g
Approximately 1 log increase at 2 and 4°C within 3 d followed by decrease.Castillejo Rodriguez and others 2000
L. monocytogenes (2 strains)AsparagusNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in 6% CO2, 79% N2, and 15% O2 in glass jars.15
4
4.0/4.8
4.2/4.8
6 d
21 d
~7.3
~5.8/6.5
CFU/g CFU/gAsparagus first became unacceptable for consumption on day 6 (15°C) or day 21 (4°C).Berrang and others 1989b
L. monocytogenes (2 strains)AsparagusNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
4.0/4.8
4.2/4.8
4 d
14 d
~7.0
~5.0/5.5
CFU/g CFU/gAsparagus first became unacceptable for consumption on day 4 (15°C) or day 14 (4°C).Berrang and others 1989b
L. monocytogenes (2 strains)BroccoliNRDip inoculation, 1 min. Cells suspended in 0.1M potassium phosphate buffer.Samples stored in 10% CO2, 79% N2, and 11% O2 in glass jars.15
4
5.0/5.5
4.0
10 d
21 d
~8.8
~4.0/4.5
CFU/g CFU/gBroccoli first became unacceptable for consumption on day 10 (15°C) or day 21 (4°C).Berrang and others 1989b
L. monocytogenes (2 strains)BroccoliNRDip inoculation, 1 min. Cells suspended in 0.1 M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
5.6
4.0
10 d
21 d
~8.7
~3.8/4.0
CFU/g CFU/gBroccoli first became unacceptable for consumption on day 6 (15°C) or day 14 (4°C).Berrang and others 1989b
L. monocytogenes
(5 strains)
Butternut squash6.3Cell suspension, 10 ml of cells added to sample. Cells suspended in 0.1% peptone.2.5-cm cubes, inoculated, and transferred to a foam tray. Sealed and stored in a bag.4
10
3.09 d~6.5
~8.5
CFU/g-Farber and others 1998
L. monocytogenes (1 strain)Cabbage (shredded)NRCells suspended in Butterfield's phosphate buffer, 1 ml added to sample.Samples in stored gas impermeable plastic bags and sealed in ambient atmosphere.53.613 d/17 d4.6/2.1CFU/g-Kallander and others 1991
L. monocytogenes (1 strain)Cabbage (shredded)NRCells suspended in Butterfield's phosphate buffer, 1 ml added to sample.Samples in stored gas impermeable plastic bags and sealed in 70% CO2 and 30% N2.  held refrigerated for first 24 h.53.017 d~4.9CFU/g-Kallander and others 1991
L. monocytogenes (1 strain)Cabbage (shredded)6.32 (day 1)Cells suspended in Butterfield's phosphate buffer, 1 ml added to sample.Samples in stored gas impermeable plastic bags and sealed in ambient atmosphere.  held refrigerated for first 24 h.254.12 d/6-9 d~6.0/<1.3CFU/g-Kallander and others 1991
L. monocytogenes (1 strain)Cabbage (shredded)6.32 (day 1)Cells suspended in Butterfield's phosphate buffer, 1 ml added to sample.Samples stored in gas impermeable plastic bags and sealed in 70% CO2 and 30% N2.254.02 d/6-9 d~4.5/<1.3CFU/g-Kallander and others 1991
L. monocytogenes
(1 strain)
Cabbage (shredded)NRCells suspended in 0.1M potassium phosphate buffer and added to sample.Samples were mixed, drained and adjusted to incubation temperature within 3 h.54.025-64 d~8.0CFU/g-Beuchat and others 1986
L. monocytogenes
(5 strains)
CarrotNRCell suspension, 1 to1.6 ml of inoculum injected through a gas-tight septum. Cells suspended in 0.1% peptone.Samples purchased from the store. Stored in original packaging.4
10
2.3
2.3
9 d
9 d
1.0
<1.0
CFU/g-Farber and others 1998
L. monocytogenes (2 strains)Carrot (shredded)-Dip inoculation, cells suspended in 0.1 M potassium phosphate buffer.Carrots washed or unwashed in 200-250 ppm prior to shredding. Stored in ambient air or in 3% O2 and 97% N2.5
15
1.1-2.6
<1.0
24 d
7 d
3.8-4.6
3.4-5.8
CFU/gSimilar results obtained for unwashed carrots stored at 5°C. Population declined to <1 log CFU/g (day 7) in unwashed carrots stored at 15°C.Beuchat and Brackett 1990a
L. monocytogenes (2 strains)Carrot (whole)-Dip inoculation, cells suspended in 0.1 M potassium phosphate buffer.Carrots washed or unwashed in 200-250 ppm. Stored in ambient air or in 3% O2 and 97% N2.5
15
1.8-2.4
2.5-3.0
18 d
7 d
<1.0
<1.0
CFU/g-Beuchat and Brackett 1990a
L. monocytogenes (2 strains)CauliflowerNRDip inoculation, 1 min. Cells suspended in 0.1 M potassium phosphate buffer.Samples stored in 3% CO2, 79% N2, and 18% O2 in glass jars.15
4
3.4/4.0
2.8/ 3.0
8 d
21 d
~6.8/7.1
~3.0/3.6
CFU/g CFU/gCauliflower first became unacceptable for consumption on day 8 (15°C) or day 21 (4°C).Berrang and others 1989b
L. monocytogenes (2 strains)CauliflowerNRDip inoculation, 1 min. Cells suspended in 0.1 M potassium phosphate buffer.Samples stored in ambient air in glass jars.15
4
3.4/4.0
2.8/ 3.0
8 d
14 d
~6.2/6.8
~2.3/3.6
CFU/g CFU/gCauliflower first became unacceptable for consumption on day 6 (15°C) or day 14 (4°C).Berrang and others 1989b
L. monocytogenes
(5 strains)
Coleslaw6.6Cell suspension, 1 to1.6 ml of inoculum injected through a gas-tight septum. Cells suspended in 0.1% peptone.Samples were purchased from the store. Stored in original packaging.4
10
2.5
2.5
9 d~4.0
~5.0
CFU/g-Farber and others 1998
L. monocytogenes
(1 strain)
Endive (chicory)NRCell suspension added to samples.Stored in moderate vacuum packaging containers under moderate vacuum.6.53.37 d~2.5CFU/g-Aytac and Gorris1994
L. monocytogenes
(1 strain)
Endive (chicory)NRCell suspension added to samples.Stored in moderate vacuum packaging container in ambient air.6.53.37 d~5.2CFU/g-Aytac and Gorris1994
L. monocytogenes (1 strain)Endive (broad leaved)-Dip inoculation, 10 min. Cells suspended in sterile distilled water.Samples were inoculated, drained, sealed, and stored in polypropylene pouches.104.57 d5.2CFU/g-Carlin and Nguyen-the 1994
L. monocytogenes (1 strain)Endive (curly leaved)-Dip inoculation, 10 min. Cells suspended in sterile distilled water.Samples were inoculated, drained, sealed, and stored in polypropylene pouches.104.27 d4.5CFU/g-Carlin and Nguyen-the 1994
L. monocytogenes (3 strains)Endive (broad leaved)NRDip inoculation, 10 min. Cells suspended in sterile distilled water. Strains inoculated independently.Samples were inoculated, drained, sealed, and stored in polypropylene pouches.104.1-4.87 d6.1-7.0CFU/gWhen lower inoculation levels were used, populations inccreased faster during initial storage but final populations were lower.Carlin and others 1995
L. monocytogenes (3 strains)Endive (broad leaved)NRDip inoculation, 10 min. Cells suspended in sterile distilled water.Stored in 90-mm diameter petri dishes and placed in plastic boxes. Boxes contained wet absorbent paper. Stored in modified atmosphere of 10% CO2, 10% O2.3
10
~3.9-4.0
~4.1-4.2
10 d
8 d
~3.5-4.5
~6.2-6.7
CFU/gHigher initial CO2 levels caused significant spoilage.Carlin and others 1996
L. monocytogenes (3 strains)Endive (broad leaved)NRDip inoculation, 10 min. Cells suspended in sterile distilled water.Stored in 90-mm diameter petri dishes and placed in plastic boxes. Boxes contained wet absorbent paper. Stored in ambient air.3
10
~3.6-3.9
~4.1-4.2
10 d
8 d
~4.0-5.0
~6.2-6.7
CFU/g-Carlin and others 1996
L. monocytogenes
(5 strains)
Onion5.8Cell suspension, 10 ml of cells added to sample. Cells suspended in 0.1% peptone.1-cm slices, inoculated, and transferred to foam trays. Sealed and stored in bags.4
10
4.0
3.5
9 d~3.0
~4.8
CFU/g-Farber and others 1998
L. monocytogenes
(5 strains)
Rutabaga6.3Cell suspension, 10 ml of cells added to sample. Cells suspended in 0.1% peptone.0.5 by 0.5 by 7.5cm sticks, inoculated, and transferred to foam trays. Stored and sealed in bags.4
10
3.0
3.0
9 d~4.0
~6.0
CFU/g-Farber and others 1998
L. monocytogenes
(5 strains)
Stir fry vegetables6.8Cell suspension, 1-1.6 ml of inoculum injected through a gas-tight septum. Cells suspended in 0.1% peptone.Samples purchased from the store. Stored in original packaging.4
10
2.5
2.5
9 d~3.0
~5.5
CFU/g-Farber and others 1998
Samonella TyphiJicama (cubes)3.30Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, 0.05 ml lemon juice added, inoculated, and stored in covered glass trays.25-273.16 h3.4CFU/cube-Fernandez Escartin and others 1989
S. TyphiJicama (cubes)5.97Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated, and stored in covered glass trays.25-273.26 h4.7CFU/cube-Fernandez Escartin and others 1989
Shigella dysenteriae
(1 strain)
Jicama (cubes)5.97Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated and stored in covered glass trays.25-271.56 h2.2CFU/cm2-Fernandez Escartin and others 1989
S. flexneri
(1 strain)
Carrot saladNRCells suspended in water and added to sample.Samples stored in 50 ml polypropylene centrifuge tubes.5~6.711 d~2.5CFU/g-Rafii and Lunsford 1997
S. flexneri
(1 strain)
Green pepper (chopped)NRCells suspended in water and added directly to sample.Samples stored in 50 ml polypropylene centrifuge tubes.46.712 d4.3CFU/g-Rafii and Lunsford 1997
S. flexneri
(1 strain)
ColeslawNRCells suspended in water and added directly to sample.Samples stored in 50 ml polypropylene centrifuge tubes.4~5.116 d~4.3CFU/g-Rafii and Lunsford 1997
S. flexneri
(1 strain)
Cabbage (chopped)NRCells suspended in water, added directly to sample.Samples stored in 50 ml polypropylene centrifuge tubes.46.526 d3.1CFU/g-Rafii and Lunsford 1997
S. flexneri (1 strain)Onion (chopped)NRCells suspended in water and added to sample.Samples stored in 50 ml polypropylene centrifuge tubes.46.712 d5.3CFU/g-Rafii and Lunsford 1997
S. sonneiParsley (chopped leaves)NRParsley was immersed in suspension of cells in 0.05 M potassium phosphate buffer (pH 6.8) for 1 min while being agitated, then dried at 21°C for 1 h.Leaves (300 g) placed in 9-liter pans.213.51 d6.2CFU/gSubjective examination revealed that parsley was edible.Wu and others 2000
S. sonneiParsley (whole leaves)NRParsley was immersed in suspension of cells in 0.05 M potassium phosphate buffer (pH 6.8) for 1 min while being agitated, then dried at 21°C for 1 h.Leaves (300 g) placed in 9-liter pans.213.27 d3.8CFU/gSubjective examination revealed that parsley was edible.Wu and others 2000
S. sonneiParsley (whole or chopped leaves)NRParsley was immersed in suspension of cells in 0.05 M potassium phosphate buffer (pH 6.8) for 1 min while being agitated, then dried at 21°C for 1 h.Leaves (300 g) placed in 9-liter pans.43.2-3.514 d0.4-0.8CFU/gSubjective examination revealed that parsley was edible.Wu and others 2000
S. sonnei
(3 strains)
Parsley (chopped)-Dip inoculation, cells suspended in 0.05 M potassium phosphate-buffered saline. 1200 g sample inoculated and dried. Chopped after drying.Stored in 9-liter plastic pans.4
21
6.48/3.492 d~9.2/~6.3CFU/gThe pathogen grew to 9.2 and 6.3 log CFU/g within 2 d at 21°C, followed by a decline. Inoculated chopped parsley stored at 4°C declined throughout a 14 day storage period.Wu and others 2000
S. sonnei
(3 strains)
Parsley (whole, leaves)-Dip inoculation, cells suspended in 0.05 M potassium phosphate-buffered saline. 1200 g sample inoculated and dried.Stored in 9-liter plastic pans.213.23/6.197 d/7 d~3.0/~6.5CFU/gAn increase of <1 log within 1 day at 21°C, followed by a decline in population after 2 d. Inoculated parsley stored at 4°C declined thoroughout the 14 day storage period.Wu and others 2000
S. sonnei
(1 strain)
Cabbage (shredded)6.8Dip inoculation, cells suspended in Butterfield's phosphate buffer.Stored under vacuum in gas impermeable bags.24+ 2
0-6
3.2
3.5
1 d/7 d
7 d
7.0/<-0.52
3.5
MPN/g-Satchell and others 1990
S. sonnei
(1 strain)
Cabbage (shredded)6.8Dip inoculation, cells suspended in Butterfield's phosphate buffer.Stored in modified atmosphere (30% N2, 70% CO2) in gas impermeable bags.24+ 2
0-6
3.4
2.6
1 d/7 d
7 d
 
7.0/3.7
2.5
MPN/g-Satchell and others 1990
S. sonnei
(1 strain)
Cabbage (shredded)6.8Dip inoculation, cells suspended in Butterfield's phosphate buffer.Stored anaerobically in gas impermeable bags.24+ 2
0-6
3.6
3.8
2 d/7 d
7 d
7.0/4.4
-0.081
MPN/g-Satchell and others 1990
Shigella
(3 species)
Jicama (cubes)5.97Spot inoculation, cells suspended in saline. 1 drop (Pasteur pipette) inoculated per cube.12 cm2 cubes, inoculated and stored in covered glass trays.25-272.5-2.66 h3.3-4.0CFU/cm2S. sonnei,
S. flexneri,
S. dysenteriae
Fernandez Escartin and others 1989
aNot reported


 

Table G/S-5: Survival and Growth of Pathogenic Bacteria on Raw Lettuce and Salads

PathogenProduce TypepHMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Clostridium botulinum (10 strains)Lettuce (intact)6.2Spot inoculation, spores prepared in broth,  heat shocked, and diluted in distilled water.Samples stored in polyethylene bags and vacuum sealed.4
12
21
2.050 d
13 d
6 d
NRNRAt 4°C, 0/6 toxic. At 12°C, 0/6 toxic. At 21°C, 2/6 toxic. Gross spoilage observed when toxin detected.Larson and others 1997
C. botulinum
nonproteolytic
(8 strains)
Mixed saladNRaSpore suspension, 1 ml injected through gas-tight septum.Samples in original package.5
10
15
25
3.021 d
21 d
14 d
4 d
3.7
3.7
>4.5
>4.4
spores/gNo toxin at 5 or 10°C. Toxin detected at 14 d (15°C) and 4 d (25°C). Moderate browning at time of toxin detection. Final pH 5.3-5.9.Austin and others 1998
C. botulinun proteolytic
(10 strains)
Mixed saladNRSpore suspension, 1 ml injected through gas-tight septum.Samples in original package.15
15
25
1.0
2.0
21 d
21 d
7 d
NR
NR
>4.5
spores/gNo toxin at 15°C. Extensive decay observed when toxin detected (7 d at 25°C).Austin and others 1998
C. botulinum
(12 strains)
Romaine lettuce (shredded)NRSpore suspension (1 ml), heat shocked, sprayed onto sample. Spores were suspended in gel-phosphate buffer.Samples were sealed in 3-qt pouches and stored vented or not vented. Vented bags were placed with space between samples so that air could circulate.4.4
12.7
21
2.0
2.0
2.0
28 d
28 d
28 d
2.0
2.1
NDb
MPN spores/gNo toxin detected in samples stored at 4.4°C or 12.7°C. Toxin detected in non-vented samples stored at 21°C after 14 d and in vented samples after 21 d. Samples were judge to be inedible prior to toxin detection.Petran and others 1995
C. botulinum
nonproteolytic
(8 strains)
Romaine lettuceNRSpore suspension, 1 ml injected through gas-tight septum.Samples in original package.5
10
3.021 dNRspores/gToxin not detected. No change in appearance.Austin and others 1998
C. botulinun proteolytic
(10 strains)
Romaine lettuceNRSpore suspension, 1 ml injected through gas-tight septum.Samples packaged in film.15
15
25
1.0
2.0
21 d
21 d
9 d
NR
NR
>4.5
spores/gToxin not detected at 15°C. No change in appearance. Extensive decay observed when toxin detected at 25°C.Austin and others 1998
Escherichia coli O157:H7Lettuce (shredded)~7.4Dip inoculation, 1 min. Cells suspended in deionized water.Stored in polyolefin L-bags consisting 3% O2 and 97% N2.5
12
21
5.314 d
3 d/14 d
3 d/7 d
3.1
7.0/8.0
8.5/8.7
CFU/g-Abdul-Raouf and others 1993
E. coli O157:H7Lettuce (shredded)~7.4Dip inoculation, 1 min. Cells suspended in deionized water.Stored in air in polyolefin L-bags.5
12
21
5.314 d
3 d/14 d
3 d/7 d
4.2
6.8/7.5
8.5/8.8
CFU/g-Abdul-Raouf and others 1993
E. coli O157:H7Iceberg lettuce (shredded)NRDip inoculation (1 min) in 0.1 M phosphate buffer (pH 7.0) suspension before mild heat treatment (50°C, 90 s).Stored in plastic bags for up to 18 d.53.418 d2.9CFU/gCounts on heated lettuce were similar to counts on unheated lettuce.Li and others 2001
E. coli O157:H7Iceberg lettuce (shredded)NRDip inoculation (1 min) in 0.1 M phosphate buffer (pH 7.0) suspension before mild heat treatment (50°C, 90 s).Stored in plastic bags for up to 7 d.153.47 d7.6CFU/gCounts on heated lettuce were significantly higher than counts on unheated lettuce stored for 4 and 7 d.Li and others 2001
E. coli O157:H7Iceberg lettuce (pieces) Dip inoculation, 30 s. Cells suspended in trypticase soy broth.Stored in sealed plastic bags.4~3.94~3.7CFU/g-Lin and others 2000
Listeria monocytogenes (1 strain)Butterhead lettuceNRDip inoculation, 10 mins. Cells suspended in sterile distilled water.Samples were drained on absorbent paper, sealed, and stored in polypropylene pouches.104.47 d5.3CFU/g-Carlin and Nguyen-the 1994
L. monocytogenes (5 strains)Ceasar salad6.3Cells suspended in 0.1% peptone, 1-1.6 ml injected through a gas-tight septum.Samples purchased from store, inoculated, and stored in original packaging.4
10
~3.0
~3.0
9 d~3.0
~6.0
CFU/g-Farber and others 1998
L. monocytogenes
(1 strain)
Lettuce (pieces)NRInoculated with contaminated gloved hands. Inoculum diluted in sterile water.Stored in sealed plastic bags.5
12
25
5.4
3.8
4.6
14 d
14 d
14 d
6.5
6.9
5.9
CFU/gLevels of L. monocytogenes estimated by randomly selecting 5 colonies from plate count agar and streaking onto McBride Listeria Agar.Steinbruegge and others 1988
L. monocytogenes (2 strains)Lettuce (shredded)NRDip inoculation, 1 min. Cells suspended in 0.1 M phosphate buffer.Produce washed in 200-250ppm chlorine and stored in Cryvovac L-bags in 3% O2 and 97% N2.5
10
4.1
4.2
15 d
10 d
~5.0
~8.0
CFU/g-Beuchat and Brackett 1990b
L. monocytogenes (2 strains)Lettuce (shredded)NRDip inoculation, 1 min. Cells suspended in 0.1 M phosphate buffer.Produce not washed and stored in Cryvovac L-bags in 3% O2 and 97% N2.5
10
4.8
4.8
15 d
10 d
~4.8
~7.7
CFU/g-Beuchat and Brackett 1990b
L. monocytogenes (2 strains)Lettuce, whole leavesNRDip inoculation, 1 min. Cells suspended in 0.1 M phosphate buffer.Produce not washed and stored in Cryvovac L-bags in 3% O2 and 97% N2.5
10
4.6
4.7
15 d
10 d
5.4
6.8
CFU/g-Beuchat and Brackett 1990b
L. monocytogenes (2 strains)Lettuce, whole leavesNRDip inoculation, 1 min. Cells suspended in 0.1M phosphate buffer.Produce washed in 200-250ppm chlorine and stored in Cryvovac L-bags in 3% O2 and 97% N2.5
10
4.3
4.7
15 d
10 d
4.9
6.8
CFU/g-Beuchat and Brackett 1990b
L. monocytogenes (1 strain)Lamb's lettuceNRDip inoculation, 10 mins. Cells suspended in sterile distilled water.Samples were drained on absorbent paper, sealed, and stored in polypropylene pouches.104.17 d4.0CFU/g-Carlin and Nguyen-the 1994
L. monocytogenesIceberg lettuce (pieces) Dip inoculation, 30 s. Cells suspended in trypticase soy broth.Stored in sealed plastic bags.4~4.14~4.4CFU/g-Lin and others 2000
Salmonella BaildonIceberg lettuce (shredded)6.06-7.00Cells suspended in deionized water, 30 ml mixed with 2270 g of lettuce.Lettuce (450g) was sealed in plastic bags. Stored for up to 12 d.40.312 d<1.0CFU/gDetected in 6 of 6 enriched samples (25 g) after 2, 5, and 8 d, and 1 of 6 samples after 12 d.Weissinger and others 2000
S. BaildonIceberg lettuce (shredded)6.06-7.00Cells suspended in deionized water; 30 ml mixed with 2270 g of lettuce.Lettuces (450g) was sealed in plastic bags. Stored for up to 12 d.43.312 d1.8CFU/gCounts were 3.24, 3.07, and 2.69 log10 CFU/g after 2, 5, and 8 d, respectively.Weissinger and others 2000
S. MontevideoIceberg lettuce (pieces) Dip inoculation 30 s. Cells suspended in trypticase soy broth.Stored in sealed plastic bags.4~4.14~4.4CFU/g-Lin and others 2000
Shigella sonneiLettuce (shredded)NRSpot inoculated.Strain isolated from outbreak and inoculated onto lettuce.5NR7 d
 
1 log decreaseCFU/g-Davis and others 1988
S. sonneiLettuce (shredded)NRSpot inoculated.Strain isolated from outbreak and inoculated onto lettuce.153.1--CFU/g5 h generation time.Davis and others 1988
S. sonnei
(1 strain)
Lettuce (shredded)NRSpot inoculated.Strain isolated from outbreak and inoculated onto lettuce.223.112 h6.3CFU/gS. sonnei survived but did not grow at 5 and 15°C.Davis and others 1988
aNot reported
bNot determined


 

Table G/S-6: Survival and Growth of Pathogenic Bacteria in Unpasteurized Juice

PathogenJuice TypepHMode of InoculationConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Escherichia coli O157:H7
(1 strain)
Apple, cider3.7Cells suspended in 0.85% NaCl solution, 1 ml added to 100 ml sample.Full strength apple cider. Stored in flask on a shaker at 150 rpm.2666 d4.5CFU/ml-Janisiewicz and others 1999
E. coli O157:H7Apple, cider3.6-4.0Cells suspended in 0.1 M phosphate buffered saline, 0.5 ml added to sample.6 different lots of apple cider used.85.015-34 d<1.0CFU/mlPopulations initially increased slightly, remained stable through day 12 then decreased to undetectable levels. Growth was questioned by authors. Addition of sodium benzoate (0.1%) resulted in more rapid decline (undetectable between day 3-15).Zhao and others 1993
E. coli O157:H7Apple, cider3.6-4.0Cells suspended in 0.1 M phosphate buffered saline, 0.5 ml added to sample.6 different lots of apple cider used.82.011-15 d<1.0CFU/mlSteady population decline.Zhao and others 1993
E. coli O157:H7 (2 strains)Apple, cider (filter sterilized)3.5Culture grown in tryptic soy broth, added to sample.Inoculum grown in apple juice adjusted to pH 6.5.21
4
~5.37 d
7 d
<1.5
2.2
CFU/ml-Uljas and Ingham 1998
E. coli O157:H7Apple, cider3.6-4.0Cells suspended in 0.1 M phosphate buffered saline, 0.5 ml added to sample.6 different lots of apple cider used.255.03-6 d<1.0CFU/mlInitial increase in population 24-48 h followed by decline. Growth was questioned by authors.  higher numbers achieved in higher pH juice. More rapid decline when yeast levels were high.Zhao and others 1993
E. coli (O157:H7)Apple, cider3.6-4.2NRRoom temperature for up to 11 d.20-25°C4.37 d2.5 - 41CFU/mlRate of inactivation in cider from McIntosh apples was more rapid than in cider from Red delicious, Golden delicious, or Melrose apples.Dingman 2000
E. coli O157:H7Apple, juice3.70Cells suspended in 0.85% NaCl solution, 1 ml added to sample.Full strength apple juice. Stored in flask on a shaker at 150 rpm.266.06 d5.5CFU/ml-Janisiewicz and others 1999
E. coli O157:H7Apple, juice3.62Cells suspended in 0.85% NaCl solution, 1 ml added to sample.Juice diluted with 50% water. Stored in flask on a shaker at 150 rpm.266.06 d5.0CFU/ml-Janisiewicz and others 1999
E. coli O157:H7Apple, juice3.55Cells suspended in 0.85% NaCl solution, 1 ml added to sample.Juice diluted with 75% water. Stored in flask on a shaker at 150 rpm.266.06 d4.5CFU/ml-Janisiewicz and others 1999


 

Table G/S-7: Survival and Growth of Pathogenic Organism on Sprout Seeds or Raw Sprouts

PathogenProduce TypeMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Aeromonas hydrophilaSprouts, mung beanDiluted suspension inoculated onto sprouts.Stored in rigid plastic containers, 400 mB.6.55.05 d~6.8CFU/gSprouts obtained from local retail market.Aytac and Gorris 1994
A. hydrophilaSprouts, mung beanDiluted suspension inoculated onto sprouts.Stored in rigid plastic containers.6.55.07 d~9.2CFU/gSprouts obtained from local retail market.Aytac and Gorris1994
Escherichia coli O157:H7
(5 strains)
Seeds, alfalfaDip inoculation 1 min. Cells suspended in deionized water.Inoculated seeds were dried (5.1-6.2% moisture) before storage in sealed containers.5354 weeks<0.3CFU/gCounts decreased to 1.5 log10 CFU/g within 38 weeks. detected by enrichment at 54 weeks.Taormina and Beuchat 1999b
E. coli O157:H7 (5 strains)Seeds, alfalfaDip inoculation, 1 min. Cells suspended in deionized water.Inoculated seeds were dried (5.1-6.2% moisture) before storage in sealed containers.25354 weeks<0.3 Counts decreased to 0.74 and <0.3 log10 CFU/g after 8 and 12 weeks, respectively. detected by enrichment after 38 weeks but not 54 weeks.Taormina and Beuchat 1999b
E. coli O157:H7 (5 strains)Seeds, alfalfaDip inoculation, 1 min. Cells suspended in deionized water.Inoculated seeds were dried (5.1-6.2% moisture) before storage in sealed containers.37354 weeks<0.3 Counts decreased and <0.3 log10 CFU/g within 8 weeks. detected by enrichment after 38 weeks, but not 54 weeks.Taormina and Beuchat 1999b
E. coli O157:H7 (5 strains)Sprouts, alfalfaDip inoculation of seeds, 1 min. Cells suspended in Butterfield's phosphate buffer.Counts were monitored during sprout production in glass jars.25NR5 d7.1-8.0CFU/gSeeds were treated with disinfectants before sprouting.Lang and others 2000
E. coli O157:H7 (5 strains)Sprouts, alfalfaDip inoculation of seeds, 1 min. Cells suspended in deionized water. Sprouts produced from inoculated, dried seeds.Counts were monitored during sprout production in plastic boxes.212.372 h7.1CFU/gSprouts contained 7.4 and 7.2 log10 CFU/g after 24 and 48 h, respectively.Taormina and Beuchat 1999a
E. coli O157:H7Sprouts alfalfaDip inoculation of seeds, 10 min. Cells suspended in 0.1% peptone.Counts were monitored during sprout production in covered trays.223.110 d5.7CFU/gCounts reached ca. 5.8 log10 CFU/g within 2 d.Castro-Rosas and Escartin 2000
E. coli O157:H7 (5 strains)Sprouts alfalfaSprouts were produced at 21°C from inoculated seeds containing 2.7 log10 CFU/g.Stored in closed plastic boxes.96.0-6.912 d5.6-6.5CFU/gSubjective evaluation revealed sprouts were edible.Taormina and Beuchat 1999a
Salmonella
(5 serotypes)
Sprouts alfalfaSpot inoculation (0.1 ml) of 10 g of sprouts. Cells were suspended in 0.05 M phosphate buffer (pH 6.8).Stored in closed clear plastic boxes.107.711 d6.9CFU/gSprouts were subjectively judged to be edible after 11 d.Weissinger and others 2001
S. StanleySeeds, alfalfaDip inoculation 1 min. Cells suspended in deionized water.Inoculated seeds were dried before storage in sealed containers.8, 212.59 weeks1.81CFU/gSeeds stored at 8°C for 9 weeks, then 21°C for 8 weeks contained 0.92 log10 CFU/g.Jaquette and others 1996
S. StanleyAlfalfa seedsDip inoculation, cells suspended in 30 ml deionized water, seeds added to suspension and mixed for 1 min.Seeds placed on wire screens, dried under a laminar flow hood for 24 h. Seeds stored in plastic bags at 21°C for 48 h and then stored at 8°C.212.58 weeks0.9CFU/g-Jaquette and others 1996
S. TyphiSprouts, alfalfaDip inoculation of seeds, 10 min. Cells suspended in 0.1% peptone.Counts were monitored during sprout production in covered trays.222.56 d3.7CFU/gCounts increased to ca. 6.1 log10 CFU/g within 1 d, then decreased through 6 d.Castro-Rosas and Escartin 2000
S. TyphiSprouts, alfalfaDip inoculation of seeds, 10 min. Cells suspended in 0.1% peptone. Sprouts produced at 22°C for 7 d.Stored in closed trays.4-74.815 d4.5CFU/gDecreases have no practical significance to safety.Castro-Rosas and Escartin 2000
S. TyphiSprouts alfalfaSeeds were germinated for 24 h, then inoculated with cells suspended in 0.1% peptone.Counts were monitored during sprout production in covered trays.223.48 d2.4CFU/gCounts decreased by ca. 1 log10, suggesting inability to compete with aerobic microorganisms, which were present at 7.5 log10 CFU/g when sprouts were inoculated with S. Typhi.Castro-Rosas and Escartin 2000
Vibrio choleraeSprouts, alfalfaDip inoculation of seeds, 10 min. Cells suspended in 0.1% peptone.Counts were monitored during sprout production in covered trays.222.56 d3.7CFU/gCounts increased to ca. 5.8 log10 CFU/g within 1 d, then decreased through 6 d.Castro-Rosas and Escartin 2000
V. choleraeSprouts alfalfaSeeds were germinated for 24 h, then inoculated with cells suspended in 0.1% peptone.Counts were monitored during sprout production in covered trays.222.58 d0.5CFU/gCounts decreased by ca. 2 log10, suggesting inability to compete with aerobic microorganisms, which were at 7.5 log10 CFU/g when sprouts were inoculated with V. cholerae.Castro-Rosas and Escartin 2000
V. choleraeSprouts, alfalfaDip inoculation of seeds, 10 min. Cells suspended in 0.1% peptone. Sprouts produced at 22°C for 7 d.Stored in closed trays.4-73.115 d2.1CFU/gDecreases have no practical significance to safety.Castro-Rosas and Escartin 2000


 

Table G/S-8: Survival of Pathogenic Viruses on Raw Produce

PathogenProduce TypeMode of InoculationStorage ConditionsTemperature (°C)Initial Counts (log10 CFU)Incubation TimeFinal Counts (log10 CFU)UnitCommentsReference
Coxsackie virus B5Carrot, whole0.05 ml spot inoculated onto sample. Virus suspended in water.Samples were left uncovered.4~2.61 d
5 d
~1.6
<0.6
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Carrot, whole0.05 ml spot inoculated onto sample. Virus suspended in dilute feces (1%).Samples were left uncovered.4~2.61 d
5 d
~1.7
~1.2
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Carrot, wholeSpot inoculation, 0.05 ml inoculated onto sample. Virus suspended in undiluted feces.Samples were left uncovered.4~2.61 d
5 d
~1.9
~1.4
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Celery0.05 ml spot inoculated onto sample. Virus suspended in water or dilute feces (1%).Samples were enclosed in polyethylene bags which contained a dish of water to maintain humidity.4~2.68 d~2.6PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Celery0.05 ml spot inoculated onto sample. Virus suspended in water or dilute feces (1%).Samples were left uncovered.4~2.61 d~2.0PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Lettuce, piecesSpot inoculation, 0.1 ml inoculated onto each 16-mm disc. Virus grown in hep-2 cells, diluted in phosphate buffered saline.Lettuce discs were stored in capped storage flasks with no moisture.42.07 d~1.9--Konowalchuk and Speirs 1974
Coxsackie virus B5Lettuce, piecesSpot inoculation, 0.1ml inoculated onto each 16-mm disc. Virus grown in hep-2 cells, diluted in phosphate buffered saline.Lettuce discs were stored in capped storage flasks with low moisture levels.42.07 d~1.6--Konowalchuk and Speirs 1974
Coxsackie virus B5Lettuce, piecesSpot inoculation, 0.1 ml inoculated onto each 16-mm disc. Virus grown in hep-2 cells, diluted in phosphate buffered saline.Lettuce discs were stored in capped storage flasks with high moisture levels.42.07 d~1.9PFU/sample-Konowalchuk and Speirs 1974
Coxsackie virus B5Radish, whole root0.05 ml spot inoculated onto sample. Virus suspended in water.Samples were left uncovered.4~2.61 d
5 d
~1.6
<0.6
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Radish, whole root0.05 ml spot inoculated onto sample. Virus suspended in dilute feces (1%).Samples were left uncovered.4~2.61 d
5 d
~1.8
~1.3
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Coxsackie virus B5Radish, whole root0.05 ml spot inoculated onto sample. Virus suspended in undiluted feces.Samples were left uncovered.4~2.61 d
5 d
~2.0
~1.7
PFU/samplePresence of moisture improved survival. Survival significantly better in closed containers with high humidity. Presence of feces improved survival.Konowalchuk and Speirs 1975
Enteroviruses
(5 strains)
LettuceVirus suspended in saline, 1 ml inoculated per 100 g sample.Samples were kept in 150-200 ml beakers.3.1Unknown11 d-TCD50/ml0.5 log decrease observed.Bagdasaryan 1964
Enteroviruses
(5 strains)
Tomato, wholeVirus suspended in saline, 1 ml inoculated per 100 g sample.Samples were kept in 150-200 ml beakers.3-8Unknown15 d-TCD50/ml1 log decrease observed.Bagdasaryan 1964
Enteroviruses
(5 strains)
Tomato, wholeVirus suspended in saline, 1 ml inoculated per 100 g sample.Samples were kept in 150-200 ml beakers.18-21Unknown15 d-TCD50/ml1 to 2.5 log decrease observed.Bagdasaryan 1964
Hepatitis A virus (strain hM 175)Lettuce (pieces)Inoculum contained 5% fetal bovine serum.Samples were held in loosely covered petri dishes to allow air flow.4
22
7.3
7.3
12 d
12 d
6.9
3.3
PFU/ml-Bidawid and others 2001
Hepatitis A virus (strain hM 175)Lettuce (pieces)Inoculum contained 5% fetal bovine serum.Samples held inside heat sealed plastic bag.4
22
7.3
7.3
12 d
12 d
7.1
6.1
PFU/ml-Bidawid and others 2001
Hepatitis A virus (strain hM 175)Lettuce (pieces)Inoculum contained 5% fetal bovine serum.Samples held in heat sealed plastic bags containing 70% CO2 and 30% N2.4
22
7.3
7.3
12 d
12 d
7.2
6.9
PFU/ml-Bidawid and others 2001
Rotavirus SA-11Carrot, pieces0.1 ml spot inoculated onto sample. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in uncovered containers.4
25
4.5
4.5
25 d
15 d
~1.2
~1.0
PFU/ml-Badawy and others 1985
Rotavirus SA-11Carrot, piecesImmersion inoculation, 200 ml of 105 PFU/ml. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in uncovered containers.4
25
3.0
2.8
4 d
2 d
<1.0
<1.0
PFU/ml-Badawy and others 1985
Rotavirus SA-11Lettuce, pieces0.1 ml spot inoculated onto sample. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in uncovered containers.4
25
4.530 d
25 d
2.5
1.1
PFU/ml-Badawy and others 1985
Rotavirus SA-11Lettuce, piecesImmersion inoculation, 200 ml of 105 PFU/ml. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in uncovered containers.4
25
4.525 d
15 d
~1.2
~1.2
PFU/ml-Badawy and others 1985
Rotavirus SA-11Radish, whole root0.1 ml spot inoculated onto sample. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in covered containers.4
25
4.5
4.5
30 d
4 d
~1.5
~2.5
PFU/ml-Badawy and others 1985
Rotavirus SA-11Radish, whole rootImmersion inoculation, 200 ml of 105 PFU/ml. Virus grown on MA-104 cells. Virus suspended in Tris-buffered saline.Samples stored in uncovered containers.4
25
3.6
3.6
5 d
4 d
~1.0
~2.0
PFU/ml-Badawy and others 1985


 


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