Lynne Wong's PhD thesis

In this work the model which best described the experimental data was determined in order
to extract thermodynamic parameters that provide information on the bound water content.
5.3.4 Fitting of sorption data to adsorption isotherm models
The criteria adopted to evaluate whether the isotherm model used was a good fit of the
experimental data were: 1) the coefficient of determination, R 2 , 2) the mean relative
deviation modulus P, and 3) the standard error of the estimate, E s .
n
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The mean relative deviation modulus P is defined as: P = ∑
N n = 1
m − mˆ
m
and E s is given by: E s =
∑
( m −
df
mˆ )
2
where m and mˆ are the measured and predicted EMC (on a dry basis), N is the number of
data points and df is the number of degrees of freedom which equals N minus the number
of parameters.
The criteria for accepting the fit of a model to the experimental data are that R 2 should
approach 1 and that the value of E s should be as small as possible. In addition if P is ≤ 5,
the fit is considered to be excellent. If 5 ≤ P ≤ 10, the fit is considered reasonably good,
but if P > 10, the fit is deemed poor (Lomauro et al., 1985).
In addition, Chen and Morey (1989) showed that the residuals (i.e. measured EMC –
predicted EMC) can be plotted against the predicted moisture content, and the plots
evaluated visually for randomness or pattern. If the plots have a clear pattern, the model is
not accepted.
In the present study, the above criteria were adopted to decide whether a model is a good
fit of the experimental data.
5.4 PREVIOUS RESEARCH PERFORMED TO MEASURE MOISTURE SORPTION
ISOTHERMS ON SUGAR CANE FIBRE AND SOME WOODY FIBRES
While work on the determination of adsorption isotherms of cane fibre is relatively rare,
the literature abounds with adsorption studies on fruits such as apple (Prothon and Ahrné,
2004) and pineapple (Hossain et al., 2001); on foodstuff, e.g. macaroni (Arslan and
Toğrul, 2005), semolina (Erbas et al., 2005) and alligator meat (Lopes Filho et al., 2002);
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