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May 2001


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Anthony J Fontana Jr <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Mail List <[log in to unmask]>
Tue, 1 May 2001 11:45:45 -0700
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Dear Stan Alekman,

Yes, there are references relating water activity to chemical and
biochemical activity and reaction rates. Water activity influence lipid
oxidation, non-enzymatic browning reactions, vitamin and nutrient
degradation rates, enzymatic activity, and starch gelatinization. Water
activity influences chemical reaction rates because water may act as a
solvent, reactant, or change the mobility of reactants (viscosity). In the
dry state the maximum stability is approximately 0.2-0.3aw, based on the
moisture sorption isotherm monolayer value.

If you need references or information on a particular chemical reaction
please email me. I keep a reference database on water activity applications.

Anthony Fontana
Applications Engineer

At 04:59 PM 4/28/01 -0400, you wrote:
>I have been reading the replies to the water activity and mold question.
>I wonder: Is there literature on water activity levels and chemical activity?
>Are there correlations? Limits of aw below which chemical change does not
>Stan Alekman

Anthony J. Fontana Jr. Ph.D.
Applications Engineer
Decagon Devices, Inc.     Phone 509/332-2756
950 NE Nelson Ct.          Fax 509/332-5158
Pullman, WA  99163
*       Ensuring the safety and quality of food,             *
*       pharmaceuticals, and cosmetics worldwide.      *

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