Development Of Optical Fiber Vis-Nir Spectroscopy System For Metrological Analysis On Intrinsic Qualities Of Averrhoa Carambola L
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Date
2012-04
Authors
Omar, Ahmad Fairuz
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Optical measuring techniques are one of the methods that have shown promising
results in non-destructive quality evaluation. In this research, several approach in
quantifying fruits intrinsic quality have been successfully performed through
absorbance, reflectance and interactance techniques via visible and near infrared
spectral as well as novel application of monochromatic measurement systems. The
research begins by Aquaphotomics assessment (NIR absorbance) of water-sugars
(sucrose, glucose and fructose) and water-acids (citric, tartaric, malic and oxalic)
solutions which are common biochemical composition in fruits. The intention was to
identify optical wavelengths that serve the best in quantifying parameters that are
closely related to intrinsic quality of fruits. The next stage of research was conducted
on intact fruits samples that have been categorised into preliminary samples (grapes,
limes, and carambola fruits) conducted through reflectance spectroscopy for the
measurement of SSC and pH (acidity) and intensive samples (premium export
quality of B10 carambola fruits) for the measurement of SSC, pH (acidity) and
firmness conducted through reflectance and interactance spectroscopy. This research
has successfully introduced a novel spectral analysis named as spectral linearisation
and gradient shift. These techniques were reapplied on all spectral data obtained from
water-solutes analysis as well as the spectroscopy measurement on B10 carambola.
The most significant result obtained was in the measurement of SSC using NIR
interactance spectral linearisation where the result produced is the best if compared
to multiple linear regression techniques from all range of wavelengths. Throughout
the entire spectroscopy experiment conducted in this research it can be summarised
that wavelengths 950nm, 960nm, 965nm, 970nm and 975nm have been identified to
be strongly related to absorbance of water, wavelengths between 909nm and 915nm
for absorbance of sugars and wavelengths 918-925nm and 990-996nm for
absorbance related to pH of samples. The final research stage which serves as the
main research objective was on the development of 12-bit optical fiber sensors that
operates on monochromatic mode. Two different designs have been presented and
known as Optical Fiber Red System (OF-RS) and Optical Fiber Near Infrared
System (OF-NIRS). These newly developed systems have been used for its novel
application in the measurement of pH and firmness of intact B10 carambola as well
as on pH of its juice. The results obtained using optical fiber sensors are at par with
commercial spectrometer, but with much lower cost of development, user friendly
and faster results can be produced without the need for complex data processing.
Description
Keywords
Development of optical fiber vis-nir spectroscopy system , for metrological analysis on intrinsic qualities of averrhoa carambola L