Microorganism Growth According To Water Activity

"Water Activity of Some Foods and Susceptibility to Spoilage by Microorganisms"

Adapted from Beuchat (1981)

 

aw	Microoranisms generally inhibited by aw at this point	Examples of foods within this range of water activity
0.950	Pseudomanas, Escherichia, Proteus, Shigella, Klebsiella, Bacillus, Clostridium perfringens, some yeasts	Highly perishable foods (fresh and canned fruits, vegetables, meat, fish) and milk; cooked sausages and breads; foods containing up to 4oz (w/w) sucrose or 7% NaCl
0.910	Salmonella, Vibrio parahaemolyticus, C. botulinum, Serratia, Lactobacillus, Pediococcus, some molds, Rhodotorula, Pichia	Some cheese (Cheddar, Swiss, Muenster, Provolone); cured meat (ham); some fruit juice concentrates; foods containing 55% (w/w) sucrose or 12% NaCl
0.870	Many yeasts (Candida, Torulopsis, Hansenula), Micrococcus	Fermented sausage (salami); sponge cakes' dry cheese; margaring; foods containing 65% (w/w) sucrose (saturated) or 15% NaCl
0.800	Most molds (mycotoxigenic penicillia), Staphylococcus aureus, most Saccaromyces (baillii) spp., Debaryomyces	Most fruit juice concentrates; sweetened condensed milk; chocolate syrup; maple and fruit syrups; flour; rice; pulses containing 15-17% moisture; fruit cake; country style ham; fondants; high-sugar cakes
0.750	Most halophilic bacteria, mycotoxigenic aspergilli	Jam, marmalade; marzipan; galcé fruits; some marshmallows
0.650	Xerophilic molds (Aspergillus chevalieri, A. Candidus, Wallemia sebi), Saccharomyces bisporus	Rolled oats containing ~10% moisture; grained nougats; fudge marshmallows; jelly; molasses; raw cane sugar; some dried fruits; nuts
0.600	Osmophilic yeasts (Saccaromyces rouxii), few molds (Aspergillus echinulatus, monascus bisporus)	Dried fruits containing 15-20% moisture; some toffees and caramels; honey
0.500	No microbial proliferation	Noodles, spaghetti, etc. containing ~12% moisture; spices containing ~10% moisture
0.400	—	Whole egg powder containing ~5% moisture
0.300	—	Cookies, crackers, bread crusts, etc. containing 3-5% moisture
0.030	—	Whole milk powder containing 2-3% moisture; dried vegetables containing ~5% moisture; corn flakes containing ~5% moisture; dehydrated soups; some cookies and crackers