models with user defined temperature characteristics
e.g. Dalgaard, P. 2002 . Modelling and predicting the shelf-life of
seafood. Chapter 12 in Safety and Quality Issues in Fish Processing.
Bremner, H.A. (ed). Woodhead Publishing Ltd. pp.191-219.
|Factor(s) in model
|Range of applicability
studied - depends
on selected model and temperature characteristic (See other RRS models in SSSP)
|In addition to RRS models with fixed temperature characteristics
corresponding to specific types of seafoods SSSP also include RRS-models with
user-defined temperature characteristics. These flexible RRS-models allow SSSP to predict shelf-life at different temperatures for any
food product where spoilage kinetics have been determined and the temperature
characteristic is known to the user of SSSP. Users of SSSP can select (i) the Exponential-spoilage model
(eqn. 1) and enter a slope parameter ('a'-value), (ii) the Arrhenius-spoilage model
(eqn. 2) and enter an apparent activation energy (Ea-value), or (iii)
the Square-root spoilage model (eqn.3) and enter a Tmin value.
| Two models can
be selected at the same time and this allows SSSP to be used (a) to compare two different temperature
characteristics used with the same model or (b) to compare two different models with
fixed temperature characteristics as shown in the SSSP screen just below for a
product with a shelf-life of 21 days at 5°C.
|For the seafood with shelf-life of 21 days at 5°C the SSSP screen above
shows the predicted shelf-life at 0°C to be similar when using the square-root
model and a Tmin-value of -10°C (47.2 days) or the Arrehnius model and an
apparent activation energy of 100 kJ/mole (46.4 days). However,
the Arrhenius models predicts considerably shorter shelf-life at 15°C due to the high
apparent activation energy of 100 kJ/mole selected for that model.
|SSSP allows the effect of temperature profiles on
product shelf-life to be predicted by the RRS-models with user-defined parameter
values. For a temperature profile with storage temperatures between 0°C and
15°C, the SSSP output window below clearly shows how the Arrehnius model with
an Ea-value of 100 kJ/mole (Model 2) result in shorter predicted shelf-life than
the square-root model with a Tmin-value of -10°C (Model 1) allthough the two
models both predicted a shelf-life of approximately 47 days at 0°C.