|
[SSSP home]
This section shows step-by-step how you can use the SSSP software
Models and modules can be selected form the SSSP main window i.e. the thee-view structure
shown below:
-
Chose a model or module by a double click on
the corresponding tree leaf
-
Enter product characteristics in the model
dialog box and click on the APPLY button
-
Make predictions for (i) constant temperatures,
(ii) a simple temperature
profile created manually or (iii) a temperature profile entered from a
logger file
- To display graphs, click on the graph icon
in the upper left corner of the screen
or next to the entered temperature profile data
- To save your predictions click on the
icon in the upper left corner of the screen
- To exit a model or module click on
- To obtain information click
or
|
 |
|
[SSSP home] Before
any prediction can be performed product characteristics must be entered in the RRS model dialog box
(as shown below). The
only product characteristics required is the product shelf-life at a single
known storage temperature (and then click on the APPLY button). From this information SSSP predicts shelf-life at different constant temperatures. To predict
shelf-life in days, input a storage temperature in °C in the shelf-life
prediction group-box and click on the CALCULATE button. Entering different
constant temperatures is an easy way to get an idea about the temperature sensitivity
of the product.
In the dialog box shown below the shelf-life values are indicated with two
decimals. However, from SSSP options
(Options, General) the number of decimal places can be set by the
user.
|
 |
|
Within the RRS-model dialog box and under the tab 'Series of constant
temperatures' (See picture just below) the storage temperature in °C and the
storage time in hours can be entered for each step of a temperature profile.
This is done by using the input fields as shown in the SSSP window below. Click on the
button when temperature and time for each
step of the profile has been entered. The
button allows the
last entered line to be deleted. Each step adds a new line and calculates
remaining shelf-life as shown in the grid of the SSSP window below. SSSP
calculates remaining
shelf-life for storage at 0°C, 5°C and 10°C. These values
indicate the remaining shelf-life of the product if, at a given point in time,
it was stored at one of the three constant temperatures until spoiled.
|
 |
You can include as many steps as you wish in a 'manual temperature profile'.
However, with more complicated profiles it is easier to generate a temperature
profile in a spreadsheet and to enter these data into SSSP as a ASCII file (See temperature
profiles) or by using the 'Raw data importer' ( ). Click on the graph
icon ( ) in the upper left corner of the screen to see figures of the manually entered
temperature profile and its effect on the remaining shelf-life at 0°C, 5°C and
10°C.To return from the SSSP output window with graphs (below) to the
SSSP model dialog box (above) or to select a new SSSP model or module myou
need to double click on relevane model/module in the SSSP tree-view
structure. |
 |
|
A results-bar is shown at the bottom of the SSSP output window just above.
When SSSP users click on a curve by using the right mouse bottom this results-bar
shows (i) remaining shelf-life (RSL) for the selected temperature profile,
(ii) the actual storage temperature at that particular point in time and (iii)
the remaining shelf-life (RSL) at 0°C, 5°C and 10°C. The remaining shelf life
graph includes three curves showing the remaining shelf life at 0°C, 5°C and 10
°C. In each point in time the remaining shelf-life curves indicate remaining shelf-life of
the product if stored at a constant temperature of 0°C, 5°C or 10°C until
spoiled.
Once a temperature profile has been entered in SSSP (manually, from an
ASCII file or by using the SSSP raw data importer) these data can be saved together with product characteristics in an
XML-file (Click on the
icon). In this way the data are easy to use again in
SSSP e.g. as part of a presentation or teaching session.
|
|
The SSSP raw data importer ( )
is a flexible tool that allow different types of data and various temperature
profile data to entered into SSSP by copy and paste e.g. from a spreadsheet. In
addition, SSSP can read temperature profiles in ASCII and XML formats. To import a temperature
logger profile select 'Temperature profile from logger data' (See SSSP
window below). To select and read data use the raw data importer ( )
or press the LOAD FILE button ( )
and select a TXT- or XML-file that
contains the temperature data you want to evaluated and press OPEN. More
information on this matter is found under temperature
profile data - SSSP formats. Please
observe that the product
characteristics entered into SSSP cannot be changed after a temperature profile
has been read. To evaluate different product characteristics with a given temperature profile
the file containing the temperature data must be read/loaded again.
|
 |
RRS models with user-defined temperature characteristics
In addition to RRS models with fixed temperature characteristics
corresponding to specific types of seafoods SSSP also includes RRS-models with
user-defined temperature characteristics (See SSSP window below). These flexible
RRS-models allow SSSP to predict shelf-life at different temperatures and 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
Arrhenius-spoilage model and enter an apparent activation energy (Ea-value),
(ii) the Exponential-spoilage model and enter a slope parameter value or (iii)
the Square-root-spoilage model and enter a Tmin value. Two models can
be selected at the same time to (a) compare two different temperature
characteristics used with the same model or (b) to compare two different models with fixed
temperature characteristics. Apart from their flexibility, the RRS-models with
user-defined temperature characteristics function in the same way at the
other RRS-models
described above (See also Relative rate of spoilage
(RRS) models).
|
 |
|
This module of SSSP allows shelf-life data obtained at three different
temperatures (or more) to be quantitatively compared with the Arrhenius, the Exponential or
the Square-root spoilage
models when used with a known temperature characteristic. Clearly, this
includes any of the product specific RRS-models in SSSP. Thus, users can
compare their own data with existing RRS-models in SSSP or evaluate if the
Arrhenius, Exponential or Square-root spoilage models will be appropriate for
their shelf-life data if these models are used with temperature
characteristics optimal for the specific data.
Shelf-life data can be entered manually as shown in the SSSP dialog box below.
Alternatively
data can be entered using the SSSP raw data importer ( )
or read from a file which is handy when SSSP is used for teaching.
SSSP uses relative rates of spoilage (RRS) to compare observed and predicted shelf-life data. The comparison rely on
calculation of accuracy-factor values and presentation of
observed and predicted data in graphs (See graphs in the SSSP output window below).
When accuracy-factor values are calculated from RRS-data
the reference temperature used to calulate RRS may influence the results.
Therefore, SSSP determines average accuracy-factors. These average
values are determined from the RRS data obtained by using all the tested storage
temperatures as the reference
temperature.
|
 |
 |
|
[SSSP home]. The MS-model
dialog box is working in the same
way as the RRS model dialog box described above. Predictions can only be
performed after product characteristics have been entered. Product
characteristics include (i) the initial concentration of bacteria in cfu/g
(this value must be one or above), (ii) the storage temperature and (iii)
possibly other factors like the level of carbon dioxide. When product
characteristics have been entered, click on
the APPLY button to calculate remaining shelf-life and microbial growth
rate. By entering different sets of initial concentrations of bacteria (cfu/g) and
storage conditions (temperatures or temperature and level of carbon dioxide) one
can rapidly obtain an estimate of the products sensitivity with respect to 'the
levels of contamination' and the storage conditions. The picture just below
shows the MS-model dialog box in SSSP with calculated values.
MS-models predict microbial growth and remaining shelf -life at constant or at
dynamic temperature storage conditions. Temperature profile data can be entered
as described above for the RRS-models. More information on this matter is found under temperature
profile data - SSSP formats. Click on the graph
icon in the upper left corner of the screen ( ) to show charts with a temperature
profile and its effect on microbial
growth over time and the remaining shelf-life at 0°C, 5°C and 10°C (See the SSSP
output window below).
|
 |
 |
|
[SSSP home] SSSP includes several options
that allow the appearance of graphs to be modified by (i) changing
the width of lines/curves, (ii) changing the number intervals for tichmarks on
X- and Y-axis and (iii) including or excluding data points and
legends on graphs. OPTIONS are selected from individual gaphs ( )
or in the SSSP main window (See the SSSP Options
window below)
|
|
Depending on the type
of model or module used, SSSP shows graphs of temperature profiles, remaining shelf-life,
microbial growth (Log cfu/g) or microbial growth rate (1/h). Under OPTIONS, the
GRAPH COMPARISON tab allows different overlay graphs to be produced.
To focus on particular areas of graphs SSSP includes a zooming function.
When graphs are visible the zooming function is activated by holding down the
left mouse button and then moving the mouse to mark the area to be magnified. To
revert the magnification click on the right mouse button.
|
|