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[SSSP home]
| Module |
Water activity calculation
for seafood |
| Reference |
Ross, T. and Dalgaard, P. (2004). Secondary models.
In: McKeller, R.C.and Lu, X. (Eds.), Modeling Microbial Responses in
Foods. CRC Press, Boca Raton, USA, pp. 63-150.
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To
predict the effect of NaCl on growth of microorganisms in seafood the
concentration of water phase salt (WPS) or water activity (aw)
is ofter needed (Eqn. 1-3).
Eqn. 1
For
mixtures of NaCl and water there is direct relation between the WPS
content and aw (Eqn. 2, Resnik and Chirife 1988). For cured seafood
where NaCl is the only major additive the same relation has been observed
e.g. for cold-smoked salmon (Jørgensen et al. 2000).
Eqn. 2
Eqn. 3 |
| To facilitate conversion between water
activity and WPS and to calculate WPS from seafoods content of NaCl
and dry matter a 'Water activity calculation for seafood' module has been included in
SSSP. See dialog box below. The SSSP module is not always directly related to the microbial growth models and after calculation of
water activity or WPS values these need to be use in the relevant SSSP
model. To facilitate transfer of relevant WPS values a dedicates
calculator has been added to the model-dialog boxes 'Morganella psychrotolerans -
growth and
histamine formation', 'Listeria monocytogenes in
chilled seafood' models and to 'Growth
of L. monocytogenes and LAB
in lightly preserved seafood' as shown below to the
right. |
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