46
Modern Food Microbiology
Table 3–4 Relationship between Water Activity and
Concentration of Salt Solutions
Sodium Chloride Concentration
Water Activity
Molal
Percent, w/v
0.995
0.15
0.9
0.99
0.30
1.7
0.98
0.61
3.5
0.96
1.20
7
0.94
1.77
10
0.92
2.31
13
0.90
2.83
16
0.88
3.33
19
0.86
3.81
22
Source: From The Science of Meat and Meat Products, by the
American Meat Institute Foundation. W.H. Freeman and Company,
San Francisco; copyright c
1960.
Table 3–5 Approximate Minimum a w Values for Growth of Microorganisms Important in Foods
Organisms
a w
Organisms
a w
Groups
Groups
Most spoilage bacteria
0.9
Halophilic bacteria
0.75
Most spoilage yeasts
0.88
Xerophilic molds
0.61
Most spoilage molds
0.80
Osmophilic yeasts
0.61
Specific Organisms
Specific Organisms
Clostridium botulinum, type E
0.97
Candida scottii
0.92
Pseudomonas spp.
0.97
Trichosporon pullulans
0.91
Acinetobacter spp.
0.96
Candida zeylanoides
0.90
Escherichia coli
0.96
Geotrichum candidum
ca. 0.9
Enterobacter aerogenes
0.95
Trichothecium spp.
ca. 0.90
Bacillus subtilis
0.95
Byssochlamys nivea
ca. 0.87
Clostridium botulinum, types A and B
0.94
Staphylococcus aureus
0.86
Candida utilis
0.94
Alternaria citri
0.84
Vibrio parahaemolyticus
0.94
Penicillium patulum
0.81
Botrytis cinerea
0.93
Eurotium repens
0.72
Rhizopus stolonifer
0.93
Aspergillus glaucus
∗
0.70
Mucor spinosus
0.93
Aspergillus conicus
0.70
Aspergillus echinulatus
0.64
Zygosaccharomyces rouxii
0.62
Xeromyces bisporus
0.61
∗ Perfect stages of the A. glaucus group are found in the genus Eurotium.
Modern Food Microbiology
Table 3–4 Relationship between Water Activity and
Concentration of Salt Solutions
Sodium Chloride Concentration
Water Activity
Molal
Percent, w/v
0.995
0.15
0.9
0.99
0.30
1.7
0.98
0.61
3.5
0.96
1.20
7
0.94
1.77
10
0.92
2.31
13
0.90
2.83
16
0.88
3.33
19
0.86
3.81
22
Source: From The Science of Meat and Meat Products, by the
American Meat Institute Foundation. W.H. Freeman and Company,
San Francisco; copyright c
1960.
Table 3–5 Approximate Minimum a w Values for Growth of Microorganisms Important in Foods
Organisms
a w
Organisms
a w
Groups
Groups
Most spoilage bacteria
0.9
Halophilic bacteria
0.75
Most spoilage yeasts
0.88
Xerophilic molds
0.61
Most spoilage molds
0.80
Osmophilic yeasts
0.61
Specific Organisms
Specific Organisms
Clostridium botulinum, type E
0.97
Candida scottii
0.92
Pseudomonas spp.
0.97
Trichosporon pullulans
0.91
Acinetobacter spp.
0.96
Candida zeylanoides
0.90
Escherichia coli
0.96
Geotrichum candidum
ca. 0.9
Enterobacter aerogenes
0.95
Trichothecium spp.
ca. 0.90
Bacillus subtilis
0.95
Byssochlamys nivea
ca. 0.87
Clostridium botulinum, types A and B
0.94
Staphylococcus aureus
0.86
Candida utilis
0.94
Alternaria citri
0.84
Vibrio parahaemolyticus
0.94
Penicillium patulum
0.81
Botrytis cinerea
0.93
Eurotium repens
0.72
Rhizopus stolonifer
0.93
Aspergillus glaucus
∗
0.70
Mucor spinosus
0.93
Aspergillus conicus
0.70
Aspergillus echinulatus
0.64
Zygosaccharomyces rouxii
0.62
Xeromyces bisporus
0.61
∗ Perfect stages of the A. glaucus group are found in the genus Eurotium.