the handbook of food engineering practice crc press chapter 10 ...

two regression methods. The nonlinear regression yields typically a smaller confidence
region. This means that a better estimation of shelf-life prediction and simulation is
possible (Cohen and Saguy, 1985; Haralampu et al., 1985).
Table 8 Effect of the regression method on the Arrhenius parameters derived for
nonenzymatic browning (zero-order) and thiamin retention (first - order reaction)
Regression df (a) k x 100 (b) E A /R kref (c) Ao (d) Aoavr (e)
method 25 °C 35°C 45°C 55°C 25 °C 35°C 45°C 55°C
Nonenzymatic Browning
Simulated values 15000 13.5 0.100
Two steps 1 9.1 41.6 270.2 1157.9 16067 11.7 0.100 0.105 0.095 0.098 0.098
Non-linear 19 - - - - 15796 12.2 - - - - 0.099
Thiamin retention
Simulated values 13000 0.178 100.0
Two steps 2 0.133 0.580 2.065 7.588 13125 0.175 99.7 100.4 99.2 101.5 100.2
Non-linear 16 - - - - 12985 0.182 - - - - 99.8
(a)
(b)
(c)
(d)
(e)
Degrees of freedom
Reaction rate constant: OD/g/day or day -1 for a zero and first order reaction, respectively
Units of kref at 300 K as in b above
Derived initial concentration: OD/g or mg/g thiamin for a zero and first order reaction respectively
Average of the derived initial concentration. Units as in d above
Figure 11.
Joint confidence contour (90%) for E A /R and kref derived by
one-step nonlinear least squares method, for nonenzymatic
browning.
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