1. Why
are spectroscopics methods used in cereal analysis?
With the original gravimetric and chemical methods of analysis it was
not possible to determine the properties and consistuents of grain mixtures of
flour-and-water doughs reproducibly and quickly within the time in which it was
possible to intervene in technical processes. NIR spectrometry has done away
with these difficulties and shortcomings.
2. What does NIR stand for?
The near-infrared (NIR) region is the wavelength range between 800 and
2,500 nm of the electromagnetic spectrum, i.e. a very dark red that is no
longer visible to the human eye.
3. What is meant by NIR Spectrometry?
The NIR procedure is a quick method by which individual components of a
mixture of substances can be determined qualitatively and quantitatively. Constituents
that contribute to the value of a product can be determined simultaneously
within a few minutes and called up in sequence.
4. What is difference between NIR and NIT?
The difference between reflection and transmission techniques lies in
the physical position of the detector. In the case of the reflection technique
the detector receives the light
reflected by the sample and is therefore in front of the sample chamber,
whereas in the transmission technique the detector is situated behind the
sample compartment.
5. What quality parameters can be determined by NIR?
In principle there are no limits to the uses of NIR measurements. In the
field of cereal analysis there are methods for grain and grain mixtures, flour
and semolina, doughs, liquids, suspensions and foams. Standard NIR methods are
used to determine the moisture, protein starch and fat content.
6. What is the purpose of calibration?
The NIR instrument has to be adjusted for the chemical structure to be
determined, whose vibrations are to be measured. Calibration requires a large
number of samples varying as widely as possible. Reference libraries have a
stock of spectra that have been determined over long periods.
7. Why are not all flour analyses made just by NIR although the method
is very much simpler and quicker?
NIR analysis is an indirect method that yields very accurate results
if the instrument is well calibrated. There are largely reliable calibrations
for determining total protein, the moisture content and also, with some special
instruments, the mineral content; but for the rheological tests, especially,
mathematical models have to be used which are not yet fully developed.
8. Can the quality of flour be measured in-line?
With NIR-methods, quality parameters such as protein, ash or moisture
can be determined continuously. The data can be used to control the milling
process.
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