Investigating carotenoid loss after drying and storage of

Transmittance (%)
100
90
80
70
60
50
40
30
20
10
0
200 230 260 290 320 350 380 410 440 470 500 530 560 590 620 650 680 710 740 770 800
Wavelength (nm)
78
2. Assessment of Methods
Figure 2-8: Transmittance of various polythene sheeting between 200-800 nm
Lumitherm
Red
Smart Blue
Sterilite
Clear SS
Green
Dark Blue
UV resistant polythenes were Lumitherm, Smart Blue, Sterilite. Red and Green simple
polythene stopped also wavelengths lower than 500 nm in visible. Dark Blue did not
transmit most of light. On the other hand Clear Super Strength transmitted at all
wavelength.
The same plastics were tested using sweet potato flour under artificial sun light.
Rubina® OFSP flour (1.5 g) in Petri box was exposed to artificial sun light spectrum
radiation (Sun Test CPS Model) for 30 minutes (level energy Sun test: 5 cal.(20.9 J);
total irradiance 76.2 W/m 2 ) with or without polythene coverage. Colour reading on flour
was recorded with CR200 chromameter after samples have cooled down. Colour loss
was determined by comparison with flour before exposure. L* and b* values did not
exhibited a very clear profile. a* values are shown in Figure 2-9.