NIR Reflection Spectra for Flour Samples Measured with the NIRQuest512-1.9 NIR Spectrometer and Vivo NIR Light Source
Introduction
NIR spectroscopy is commonly used to determine the composition of constituents such as moisture, protein, fat and carbohydrates in foods such as grain, flour and cereal. The composition of the sample is determined from diffuse transmittance or reflectance spectra using a carefully constructed calibration model developed using multivariate techniques.
Ocean Optics offers a full line of NIR spectrometers and accessories to enable NIR spectroscopy measurements. As described below, two new additions to the NIR product family are used for the diffuse reflection measurement of different flour samples.
NIR spectroscopy has the advantage of distinguishing specific absorbance characteristics of water and protein molecules very close to the visible range. The spectrometer’s acquisition speed, integration time handling and processing strength allow us to capture significant spectral information of the sample.
Experimental Conditions
Reflection spectra were measured for several organic flour samples (Arrowhead Mills) using the NIRQuest512-1.9 spectrometer and Vivo light source. The flour samples were put into individual plastic bags and placed on the Vivo sampling area for measurement. The WS-1 diffuse reflection standard was used as the reference and the Vivo bulbs were dimmed to reduce illumination levels. The fiber was coupled to the Vivo light source using the inner barrel from a 74-UV collimating lens.
Equipment Used
- NIRQuest512-1.9 – InGaAs array spectrometer, 512 elements, responsive from 1100-1900 nm
- Vivo light source – high-intensity source with Vis-NIR response
- QP600-2-VIS-NIR fiber – premium-grade patch cord, 600 µm diameter
- WS-1 diffuse reflection standard – diffuse PTFE standard with >95% reflectivity from 250-2200 nm
Results
Spectral data are shown in Figure 1 for Rye Flour, Oat Flour, Yellow Corn Flour, Stone Ground Whole Wheat and Barley Flour. These spectra could be used with an appropriate calibration model to determine the composition of the flour samples. The concentration of constituents such as moisture, fat, protein and carbohydrate could be determined from a single spectrum.
Figure 1: Reflection of Flour Measured with the NIRQuest512-1.9 and Vivo NIR Light Source
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