Abstract:
The consumption and
popularity of bell pepper
(Capsicum annuum L.)
are growing, mainly due to its characteristic flavour and
the wide variety of colours.
2. Objective
Can we use LED induced fluorescence/reflectance spectroscopy
to estimate physiological maturity (age) of paprika?
3. Methodology
•LEDs are used as light sources
•Ocean optics USB 4000 was used as the detector
•White, green, yellow, orange and green paprika samples
were used
•Measurements were taken twice a day
•Data were compressed and trained a linear model
4. Results
• The most suitable spectral components for different
varieties for estimating the physiological maturity is
as follows
Where, R- diffused reflectance, F xxx fluorescence excited
by LED with xxx nm centre wavelength
5. Conclusions
•Physiological maturity of a certain part of a fruit can be
estimated using LED based optical spectroscopic method
•Need to develop more robust imaging application for
estimating maturity of a whole fruit
6. Acknowledgment
This work was supported by the Swedish Research Council and through a
Linnaeus grant to the Lund Laser Centre. Support from International
Science Programme, Uppsala University is also gratefully acknowledged.
Paprika
Sample
Suitable
combination of
Spectra
Confidence
level
Truncatio
n
RMSE
(h)
R2
White R, F375 96.9 % 3 27.7 0.96
Yellow F375 98.2 % 3 23.3 0.96
Orange R 98.4 % 3 36.0 0.91
Red F355, F375 97.5 % 4 27.9 0.96
Green R, F375 93.0 % 3 21.2 0. 97
GG420 long pass
emission filter
355 nm LED AlGaN
410 nm LED
470 nm LED
InGN+Ce:YAG
750 nm LED
AlGaAs
850 nm LED
AlGaAs
375 nm LED AlGaN
395 nm LED AlGaN
UG11 short pass
excitation filter
Excitation wavelength (nm)
Emission wavelength (nm)
Spectrometer channels
Carotinide
Chlorophyll
UG
1
350 400 450 500 550 600 650 700 750 800 850
350 450 550 650 750 850
Long pass
filter GG420
Excitation
source
600 μm collection
fiber
UG1, UG11
excitation filter
Reflectance
source
Cu housing
Sample
30 mm 450 500 550 600 650 700 750 800
Wavelength (nm)
Fluorescence intensity
Fluorescence spectra ex. at 395 nm LED
t=0 min
t=3 min
t=65 min
Chlorophylls a and b and
their oxidation products give
greenish colours
Carotinides gives yellow,
orange and deep red colours