Slide 1

Ong, Law - Hygrothermal Properties of FVFs

Drying of Foods, Vegetables and Fruits 41

Figure 2.6. First order ascorbic acid degradation kinetics of apple at

different drying temperatures (Timoumi et al., 2007)

Figure 2.7. First order-carotene degradation kinetics of pumpkin at

different drying temperatures (Dutta et al., 2006)

Figure 2.8. Degradation rate constant of (a) ascorbic acid and (b) lycopene in tomato pulp as a function of moisture content and drying temperature

(Goula and Adamopoulos, 2006; Goula et al., 2006 )

0.5

0.6

0.7

0.8

0.9

1

0 50 100 150 200 250 300 350 400

Time (min)

Degradation kinetics of

ascorbic acid,

C/C

0 40°C60°C

70°C

T (°C) k (x 10 -^3 /min)

4600 0.81.1 (^)
70 1.4
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
0 10 20 30 40 50 60 70 80 90 100
Moisture content, X (% w.b.)
Degradation rate constatn, k (1/min)
50°C
60°C
70°C
80°C
90°C
for X ≤ 65
for X > 65
(a) Ascorbic acid
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 20 40 60 80 100 120 140
Time (min)
Degradation kinetics of
β-carotene, C/C
0
70°C75°C
80°C85°C
90°C100°C
T (°C) k (1/min)
7570 0.0040.00 403
(^8085 0) 0.0059.0048 (^)
10090 0.00700.0080^
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
0.0018
0.002
0 10 20 30 40 50 60 70 80 90 100
Moisture content, X (% w.b.)
Degradation rate constatn, k (1/min)
50°C
60°C
70°C
80°C
90°C
for X ≤ 55
for X > 55
(b) Lycopene