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Spectroscopic Methods




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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