Slide 1

Ong, Law - Hygrothermal Properties of FVFs

Figure 2.1. Colour changes of potato during drying at various temperatures (a) zero order kinetic model of optical density and (b) Arrhenius model
of kinetic rate constant (McMinn and Magee, 1997)

Figure 2.2. Colour changes of kiwifruit slices during drying at various temperatures (a) first order kinetic model of browning index and (b) Ar-

rhenius model of kinetic rate constant (Mohammadi et al., 2008)

(a)

0

0.05

0.1

0.15

0.2

0.25

0 200 400 600 800 1000 1200 1400

Time (min)

Optical density

30°C

45°C

60°C

T(°C) [B] 0 kb (x10-^3 /min)

30 0.0092 0.1

45 0.0063 0.2

60 0.0029 0.3

(b)

y = -3730.8x + 3.0995R (^2) = 0.985
-9.4
-9.2
-9
-8.8
-8.6
-8.4
-8.2
-8
0.00295 0.003 0.00305 0.0031 0.00315 0.0032 0.00325 0.0033 0.00335
1/T (1/K)
lnk
(a)
45
47
49
51
53
55
57
59
61
63
0 50 100 150 200 250 300 350 400 450 500
Time (min)
Browning index, BI 40°C
50°C
60°C
70°C
80°C
T( 4 °C) 0 k (1/0.0005min )
5600 0.00070.0009 (^)
7080 0.00120.0017 (^)
(b)
y = -3315.5x + 2.9483R (^2) = 0.9948
-7.8
-7.6
-7.4
-7.2
-7
-6.8
-6.6
-6.4
-6.2
0.0028 0.00285 0.0029 0.00295 0.003 0.00305 0.0031 0.00315 0.0032 0.00325
1/T (1/K)
lnk
Drying of Foods, Vegetables and Fruits