The evolutions of β-carotene and lycopene during drying are shown in Figure 2. The results showed that
both β-carotene and lycopene decreased gradually during drying. It was also observed that higher temperatures resulted in larger reduction of β-carotene and lycopene. This was probably due to the
degradation of β-carotene and lycopene might be caused by both enzymatic reaction and thermal destruction.
Lipoxygenase, an enzyme found in fresh fruits and vegetables, was responsible for the oxidative degradation
of β-carotene and lycopene [7]. Increase in drying temperatures would accelerate lipoxygenase activity
leading to higher losses of the compounds. At higher temperatures heat also could more penetrate into the
plant cells resulting in more degradation of the compounds [8]. In addition, it can be seen that the reduction
rate of lycopene was faster than that of β-carotene. The results were consistent with those of Anguelova and
Warthesem [9] who reported that the degradation rate of lycopene was more extensive than that of β-
carotene at a temperature of 60°C.