Development of Infrared Spectroscopic Techniques for the Determination of Some Quality Parameters of Palm Oil
Several parameters for good quality crude palm oil (CPO) and its fractions such as free fatty acid (FFA), oxidative value, moisture and impurities, iodine value and antioxidant composition are very crucial in palm oil industry. For trading purposes in Malaysia, the standard of these quality param...
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| Format: | Thesis |
| Language: | English English |
| Published: |
1998
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8388/1/FSMB_1998_5_A.pdf |
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| Summary: | Several parameters for good quality crude palm oil (CPO) and its
fractions such as free fatty acid (FFA), oxidative value, moisture and impurities,
iodine value and antioxidant composition are very crucial in palm oil industry.
For trading purposes in Malaysia, the standard of these quality parameters have to
be accomplished by all the refiners Association of Malaysia (PORAM) standard specifications.
Conventionally, the analytical techniques used to analyze the quality
parameters in palm oil are by wet chemical methods based on the American Oil
Chemists' Society (AOCS) procedures which involve titration. Normally this
chemical techniques require large amount of chemicals and reagents which may be unfriendly to environment and hazardous to health. Moreover, most analyses
are time consuming and laborious especially for large number of samples. To
overcome the problem, numerous studies on instrumental techniques have been
carried out over the years. From this standpoint, near infrared (NIR) spectroscopy
and Fourier transform infrared (FTIR) spectroscopy are considered the
instrumental approaches of choice.
1bree parameters were selected in the study. For the determination of
FFA, NIR transflectance and FTIR transmittance techniques were investigated.
Range of FF A concentration were prepared by hydrolyzing oil with 0.15% (w/w)
lipase in an incubator at 60°C (200 rpm). In NIR approach, sample preparation
was performed in Dutch cup and optimized calibration models were constructed
with multiple linear regression (MLR) analysis based on C=O overtone regions.
The best wavelength combinations were found to be 1882,2010 and 2040 nm for
CPO and refined bleached deodorized (RBD) oils. For FTIR technique, partial
least squares (PLS) analysis was used to replace the previous simple linear
regression model developed for predicting FFA. Both IR techniques showed
excellent results in predicting the FFA values of the unknown samples.
The determination of peroxide value (PV) was based on NIR
transmittance spectroscopy. Calibration standards (2 to 11 PV) were prepared by
oxidized CPO at 90°C. The best NIR region for predicting unknown was from
1350 to 1480 nm with referenced to single-point baseline at 1514 nm. The
standard error of performance (SEP) was similar to the calibration to within 0.1%
PV. The final aspect studied was the determination of β-carotene in CPO
using different techniques. Both FTIR and NIR spectroscopy were compared with
the UV-visible spectrophotometric reference method. PLS calibration model for
predicting β-carotene was developed for the FTIR spectral region from 976 to
926 cm⁻¹] due to trans -CH=CH- conjugated deformation modes. The study
showed that NIR spectra did not correlate well with the component of interest.
However, highest correlation was found in the visible spectral region from 546 to
819 nm. Statistical results showed that both FTIR and NIR spectroscopy can
accurately predict β-carotene to 5% error; this value was 4% higher as compared
to the reference method.
Results from this study indicated that both NIR and FTIR spectroscopy
were useful techniques for measuring palm oil quality parameters. Compared to
the conventional wet chemical method, NIR and FTIR spectroscopy are capable
of measuring hundreds of samples in a day and yet meet the trading specification.
In addition, by applying these techniques, the amount of hazardous solvents can
be reduced dramatically as well as the cost of labor. |
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